GRUNDFOS PUMP HANDBOOK
PUMP HANDBOOK
Copyright 2008 GRUNDFOS Pumps Corporation. All rights reserved. Copyright law and international treaties protect this material. No part o this material may be reproduced in any orm or by any means without prior written permission rom GRUNDFOS Pumps Corporation. Trademarks and tradenames mentioned herein are the property o their respective owners. Disclaimer All reasonable care has been taken to ensure the accuracy o the contents o this material; however, GRUNDFOS shall not be liable or responsible or any loss whether direct, indirect, incidental or consequential arising out o the use o or reliance upon any o the contents o this material.
Foreword Today’s processes place heavy demand on pumps when it comes to optimum operation, high reliability and low energy consumption. Thereore, we have developed the Grundos Pump Handbook which, in a simple simpl e manner, deals with various considerations when sizing pumps and pump systems. This handbook, developed or engineers and technicians who work with design and the installation o pumps and pump systems, includes answers to a wide range o technical questions. The handbook can either be read rom cover-to-cover or in part on specic topics. The handbook is divided into ve chapters which deal with dierent phases when designing pump systems. Chapter 1 includes a general presentation o dierent pump types and components. Also described are precautions to consider when dealing with viscous liquids. Further, the most used materials, as well as dierent types o corrosion, are presented. Terminologies in connection with reading pump perormance are presented in Chapter 2. Chapter 3 deals with system system hydraulics and some o the most important important actors to consider or optimum operation o the pump system. Pump perormance adjustment methods are discussed in Chapter 4. Chapter 5 describes lie cycle costs, as energy consumption plays an important role in today’s pumps and pump systems. We sincerely hope that you will nd this handbook useul in your daily work.
Grundos Pumps Corporation
Table o Contents
Chapter 1 Design o pumps and motors ...................... 7 Section 1.1 Pump construction ............................................................ 8 1.1.1 The centriugal pump .......... ..................... ..................... ..................... ...................... ...................... ............... 8 1.1.2 Pump curves 9 1.1.3 Characteristics o the centriugal pump. 11 1.1.4 Most common end-suction and in-line pump types. 12 1.1.5 Impeller types (axial orces). 14 1.1.6 Casing types (radial orces). 15 1.1.7 Single-stage pumps 15 1.1.8 Multistage pumps. 16 1.1.9 Long-coupled and close-coupled pumps.16 Section 1.2 Types o pumps ................................................................... 17 1.2.1 Standard pumps. 17 1.2.2 Split-case pumps 17 1.2.3 Hermetically sealed pumps. 18 1.2.4 Sanitary pumps.20 21 1.2.5 Wastewater pumps 21 1.2.6 Immersible pumps. 22 1.2.7 Groundwater pumps 23 1.2.8 Positive displacement pumps.24 Section 1.3 Mechanical shat seals .................................................. 27 1.3.1 The mechanical shat seal’s 29 components and unction 29 1.3.2 Balanced and unbalanced shat seals 30 1.3.3 Types o mechanical shat seals 31 1.3.4 Seal ace material combinations. 34 1.3.5 Factors aecting the seal perormance.36 36 Section 1.4 Motors .................................................................................... 39 40 1.4.1 Standards 40 1.4.2 Motor start-up. 46 1.4.3 Voltage supply. 47 1.4.4 Frequency converter. 47 1.4.5 Motor protection. 49
Section 1.5 Liquids ....................................................................................... 53 1.5.1 Viscous liquids. 54 1.5.2 Non-Newtonian liquids. 55 1.5.3 The impact o viscous liquids on the perormance o a centriugal pump 55 1.5.4 Selecting the right pump or a liquid with antireeze. 56 58 1.5.5 Calculation example 58 1.5.6 Computer-aided pump selection selection or dense and and viscous liquids. 58 Section 1.6 Materials................................................................................ 59 60 1.6.1 What is corrosion? 60 1.6.2 Types o corrosion.61 1.6.3 Metal and metal alloys 65 1.6.4 Ceramics. 71 1.6.5 Plastics 71 1.6.6 Rubber. 72 1.6.7 Coatings. 73
Chapter 2 Installation and perormance reading.............................................................................................................
75
Section 2.1 Pump installation ............................................................ 76 2.1.1 New installation.76 2.1.2 Existing installation-replacement.76 2.1.3 Pipe fow or single-pump installation. 77 2.1.4 Limitation o noise noise and and vibrations vibrations. 78 81 2.1.5 Sound level 81 Section 2.2 Pump perormance ........................................................ 83 2.2.1 Hydraulic terms. 83 2.2.2 Electrical terms. 90 2.2.3 Liquid properties.93
Chapter 3 System hydraulics..................................................
95
Section 3.1 System characteristics ................................................. 96 3.1.1 Single resistances.97 3.1.2 Closed and open systems 98 Section 3.2 Pumps connected in parallel and series ................... 101
3.2.1 Pumps in parallel.101 3.2.2 Pumps connected in series. 103
Chapter 4 Perormance adjustment o pumps.....................................................................................................
Chapter 5 Lie cycle costs calculation
........................ 127
Section 5.1 Lie cycle costs equation ............................................ 128 5.1.1 Initial cost, purchase price (Cic) 129 5.1.2 Installation and commissioning costs (C (Cin). 129 5.1.3 Energy costs (Ce). 130 5.1.4 Operating costs including labor (Co). 130 5.1.5 Environmental costs (Cenv). 130 5.1.6 Maintenance and repair repair costs (Cm) 131 5.1.7 Downtime costs (loss o production) (Cs). 131 5.1.8 Decommissioning or disposal costs (C (Cd).131
105
Section 4.1 Adjusting pump perormance .............................. 106 4.1.1 Throttle control.107 4.1.2 Bypass control. 107 4.1.3 Modiying impeller diameter. 108 4.1.4 Speed control. 108 4.1.5 Comparison o adjustment methods 110 4.1.6 Overall eciency eciency o the pump system.111 4.1.7 Example: Relative power consumption when the fow is reduced by 20% 111 Section 4.2 Speed-controlled pump solutions .................... 114 4.2.1 Constant pressure control 114 4.2.2 Constant temperature control. 115 4.2.3 Constant dierential pressure in a circulating system. 115 4.2.4 Flow-compensated dierential pressure control.116
Section 5.2 Lie cycle costs calculation – an example ................................................................................................
132
Appendix.......................................................................................................... 133 A) Notations and units.134 B) Unit conversion tables.135 C) SI-prexes and Greek alphabet. 136 D) Vapor pressure and specic gravity o water at dierent temperatures . 137 E) Orice . 138 F) Change in static pressure due to change in pipe diameter. 139 G) Nozzles. 140 H) Nomogram or head losses in bends, valves, etc. . 141-150 I) Periodic system. 151 J) Pump standards. 152 K) Viscosity or typical liquids as a unction o liquid temperature.153-157
Section 4.3 Advantages o speed control.................................. 117 Index ......................................................................................................... Section 4.4 Advantages o pumps with integrated requency converter............................................................................... 118 4.4.1 Perormance curves o speed-controlled pumps.119 4.4.2 Speed-controlled pumps in dierent systems.119 Section 4.5 Frequency converter.................................................... 122 4.5.1 Basic unction and characteristics.122 4.5.2 Components o the requency converter.122 4.5.3 Special conditions regarding requency converters. 124
158-162
Chapter 1. Design o pumps and motors
Section 1.1: Pump construction 1.1.1 1.1.2 1.1.3 1.1.4 1.1.5 1.1.6 1.1.7 1.1.8 1.1.9
The centriugal pump Pump curves Characteristics o the centriugal pump Most common end-suction and in-line pump types Impeller types (axial orces) Casing types types (radial orces) orces) Single-stage pumps Multistage pumps Long-coupled and close-coupled pumps pumps
Section 1.2: Types o pumps 1.2.1 1.2.2 1.2.3 1.2.4 1.2.5 1.2.6 1.2.7 1.2.8
Standard pumps Split-case pumps Hermetically sealed pumps Sanitary pumps Wastewater pumps Immersible pumps Groundwater pumps Positive displacement pumps
Section 1.1 Pump construction
1.1.1 The centriugal pump In 1689, the physicist Denis Papin invented the centriugal pump. Today, this kind o pump is the most commonly used around the world. The centriugal pump is built on a simple principle: Liquid is led to the impeller hub and is lung towards the periphery o the impeller by means o centriugal orce. Fig. 1.1.1: The liquids low through the pump
The construction is airly inexpensive, robust and simple, and its high speed makes it possible to connect the pump directly to an asynchronous motor. The centriugal pump provides a steady liquid low, and it can easily be throttled without causing any damage to the pump. See igure 1.1.1 or liquid low through the pump. The inlet o the pump leads the liquid to the center o the rotating impeller rom where it is lung towards the periphery. This construction provides high eiciency and is suitable or handling pure liquids. Pumps which have to handle impure liquids, such as wastewater pumps, are itted with an impeller that prevents objects rom getting lodged inside the pump, see section 1.2.5.
Radial low pump
Mixed l low pump
Axial l low pump
Fig. 1.1.2: Dierent kinds o centriugal pumps
I a pressure dierence occurs in the system while the centriugal pump is not running, liquid can still pass through due to its open design. As you can tell rom igure 1.1.2, the centriugal pump can be categorized in dierent groups: Radial low pumps, mixed low pumps and axial low pumps. Radial low pumps and mixed low pumps are the most common. These types o pumps are discussed on the ollowing pages with a brie presentation o a positive displacement pump in section 1.2.8.
H [ft]
10000
1000
The dierent demands on the centriugal pump’s perormance, especially with regard to head, low, and installation, together with the demands or economical operation, are only a ew o the reasons why so many types o pumps exist. Figure 1.1.3 shows the dierent pump types with regard to low and head.
100
10
H [m] 10000 6 4 2 1000 6 4
Multistage radial low pumps
2 100 6 4
Single-stage radial low pumps
2 10 6 4
Mixed low pumps
Axial low pumps
2 1
2
10
4 6 10 2
100
4 6 100 2
1000
4 6 1000 2
4 6 10000 100000 Q [m3 /h]
10000
Q [GPM] 100000
Fig. 1.1.3: Flow and head or dierent types o centriugal pumps
1.1.2 Pump curves The perormance o a centriugal pump is shown by a set o perormance curves. The perormance curves or a centriugal pump are shown in igure 1.1.4. Head, power consumption, eiciency and NPSH are shown as a unction o the low. Normally, pump curves in Grundos product guides only cover the liquid end hydraulic perormance. Thereore, the power consumption, the P2-value which is listed in the product guides as well, only covers the power going into the pump – see igure 1.1.4. The same applies or eiciency value, which only covers the liquid end (η = ηP).
[%]
60 50 40 70 60 50 40
30
Efficiency
20
30 10
20 10
0 0 P2 [hp]
5
10
15
20
25
40 Q [GPM] 0
35
30
NPSH (ft)
Power consumption
0.6
20 15 10
0.4 0.2
NPSH
5
0
0
Fig. 1.1.4: Typical perormance curves or a centriugal pump. Head, power consumption, eciency and NPSH are shown as a unction o the fow
In some pump types with integrated motors and possibly integrated requency converters, e.g. canned motor pumps (see section 1.2.3), the power consumption curve and the η-curve cover both the motor and the pump. In this case the P1-value has to be taken into account, see igure 1.1.5. In general, pump curves are designed according to Hydraulic Institute test standards or ISO 9906 Annex A, which speciies the tolerances o the curves.
η
H
[ft]
Q P1
M 3~
P2
H
ηM
ηP
Fig. 1.1.5: The curves or power consumption and eciency will normally only cover the pump part o the unit – i.e. P2 and ηP
Following is a brie presentation o the dierent pump perormance curves.
Head, the QH-curve H
The QH-curve shows the head, identiying where the pump is able to perorm at a given low, see igure 1.1.6. Head is measured in eet liquid column [t]; normally the unit eet [t] is applied. The advantage o using the unit [t] as the unit o measurement or a pump’s head is that the QH-curve is not aected by the type o liquid the pump has to handle, see section 2.2 or more inormation.
[ft]
60 50 40 30
Efficiency
20 10 0 0
5
10
15
20
25
30
35
40 Q [GPM]
Fig. 1.1.6: A typical QH-curve or a centriugal pump; low fow results in high head and high fow results in low head
Section 1.1 Pump construction
Eiciency, the η-curve The eiciency is the relationship between the supplied power and the utilized amount o power. In the world o pumps, the eiciency ηp is the relationship between the power which the pump delivers to the water (P (PH) and the power input to the shat ( P2 ):
PH QH . SG = ηp = P2 3960 x P2
side o the pump to avoid cavitation (see section 2.2.1). The NPSHr value is measured in [t] and depends on the low. When low increases, the NPSHr value increases, see igure 1.1.9. For more inormation concerning cavitation and NPSH, go to section 2.2.1.
η
[%] 80 70 60
where: SG is the speciic gravity o the liquid. Q is the low in GPM and H is the head in t. ηp is the pump eiciency For water at 68 oF and with Q measured in GPM and H in t, the hydraulic power can be calculated as:
50 40 30 20 10 0 0
25
50
75 75
1 00
125
1 50
17 5 17
200
225
250
2 75
300
325
350
3 75
Q [GPM]
Fig. 1.1.7: The eciency curve o a typical centriugal pump
PH = lb o liquid per minute . H 33,000
Power consumption, the P2-curve The relationship between the power consumption o the pump and the low is shown in igure 1.1.8. The P2-curve o most centriugal pumps is similar to the one in igure 1.1.8 where the P2 value increases when the low increases.
Q . H . SG P2 = 3960 x ηp
P2 [hp] 14 12 10 8 6 4 2 0 0
25
50
75
10 0 1 25 10
15 0 15
1 75
2 00
2 25
250
2 75
3 00
325
Q [GPM]
Fig. 1.1.8: The power consumption curve o a typical centriugal pump
As it appears rom the eiciency curve shown in igure 1.1.7, the eiciency depends on the duty point o the pump. It is important to select a pump that its the low requirements and ensures the pump is working in the most eicient low area. NPSH [ft] 20
15
NPSH - curve (Net Positive Suction Head Required)
10
5
0 0
The NPSHr value o a pump is the minimum absolute head pressure that has to be present at the suction
25
50
75
100
125
150
175 17
200
2 25
250 25
275
300 325 30
Q [GPM]
Fig. 1.1.9: The NPSH curve o a typical centriugal pump
1.1.3 Characteristics Characteristics o the centriugal pump The centriugal pump has several characteristics and the most important ones are presented in this chapter. A more thorough description o the dierent pump types are given at the end o the chapter.
• The number o stages Depending on the number o impellers in the pump, a centriugal pump can be either a single-stage pump or a multistage pump.
• The position o the pump shat shat Single-stage and multistage pumps come with horizontal or vertical pump shats and are normally designated as horizontal or vertical pumps. For more inormation, go to section 1.1.4.
• Single-suction or double-suction double-suction impellers Depending on the construction o the impeller, a pump can be itted with either a single-suction impeller or a double-suction impeller. For more inormation, go to section 1.1.5.
• Construction o the pump casing casing Two types o pump casings are discussed: Volute casing and return channels. For more inormation, go to section 1.1.6. Fig 1.1.10: Example o multiple stage pump
Section 1.1 Pump construction
1.1.4 Most common end-suction and in-line pump types
End-suction
Horizontal
Single-stage
Long-coupled
Multistage
Close-coupled
Close-coupled
End-suction pump
=
Liquid runs directly into the impeller impeller.. Inlet and outlet have a 90° angle. See section 1.1.9
In-line pump
=
Liquid runs directly through the pump in-line. The suction pipe and the discharge pipe are placed opposite one another and can be mounted directly in the piping system
Split-case pump
=
Pump with an axially divided pump housing. See section 1.2.2
Horizontal pump
=
Pump with a horizontal pump shat
Vertical Ve rtical pump
=
Pump with a vertical pump shat
Single-stage pump
=
Pump with a single impeller impeller.. See section 1.1.7
Multistage pump
=
Pump with several series-coupled stages. See section 1.1.8
Long-coupled pump
=
Pump connects to the motor by means o a lexible coupling. The motor and the pump have separate bearing constructions. See section 1.1.9
Close-coupled pump =
Pump connects to the motor by means o a rigid coupling. See section 1.1.9
In-line
Horizontal
Vertical
Split-case Single-stage
Multistage
Single-stage Long-coupled
Long-coupled
Close-coupled
Close-coupled
Section 1.1 Pump construction
1.1.5 Impeller types There are three common types o pump impellers: open, enclosed and semi-open, see igure 1.1.11. The open impeller has a series o vanes attached to the center hub and is commonly chosen or low horsepower applications o clean, non-abrasive luids or luids with large solids. The enclosed impeller has vanes sandwiched between two shrouds. While the shrouds result in a slightly lower mechanical eiciency, they decrease the amount o pump casing wear caused by dirty or abrasive liquids. This design usually includes replaceable wear rings so critical clearances can be renewed. The semi-open impeller has a single shroud on one side o the vanes and it leaves one side open. This design can handle abrasives or solids well and oten allows or simple axial adjustment o critical impeller-to-casing clearances without pump disassembly.
Axial Force Balancing A centriugal pump generates pressure, exerting orces on both stationary and rotating parts o the pump. Pump parts are made to withstand these orces. I axial and radial orces are not counterbalanced in the pump, the orces have to be taken into consideration when selecting the driving system or the pump, such as angular contact bearings in the motor. In pumps itted with a single-suction impeller, large axial orces may occur, see igures 1.1.12 and 1.1.13. These orces are balanced or avoided as ollows: • Mechanically via thrust bearings. • Via balancing holes on the impeller, see igure 1.1.14 • Via throttle regulation rom a seal ring mounted on the back o the impellers, see igure 1.1.15 • Via blades on the back o the impeller, see igure 1.1.16 • Through the use o double-suction impellers, see igure 1.1.17
Open
Semi-open
Enclosed
Fig. 1.1.11: Impeller types
Axial orces
Fig. 1.1.12: Single-suction impeller Fig. 1.1.13: Standard pump with single-suction impeller
Fig. 1.1.14: Balancing the axial orces in a single-stage centriugal pump with balancing holes only
Fig. 1.1.15: 1. 1.15: Balancing the axial orces in a single-stage centriugal pump with seal ring gap at discharge side and balancing holes
Fig. 1.1.16: Balancing the axial orces in a single-stage centriugal pump with blades on the back o the impellers
Fig. 1.1.17: Balancing the axial orces in a double-suction impeller arrangement
1.1.6 Casing types
Fig. 1.1.18: Single-suction impeller
Radial orces
Radial orces are a result o the static pressure in the casing. Thereore, axial delections may occur and lead to intererence between the impeller and the casing. The magnitude and the direction o the radial orce depend on the low rate and the head. When designing the casing or the pump, it is possible to control the hydraulic radial orces. Two casing types worth mentioning are the single-volute and the double-volute. As seen in igure 1.1.19, both casings are shaped as a volute. The double-volute has a guide vane. The single-volute pump is characterized by a symmetric pressure in the volute at the optimum eiciency point, which leads to zero radial load. At all other points, the pressure around the impeller is not symmetrically equal and consequently a radial orce is present.
Fig. 1.1.19: Single-volute casing
Double-volute casing
e c r o f l a i d a R
Single-volute casing
Double-volute casing 1.0
Q/Qopt
Fig. 1.1.20: Radial orce or single and double-volute casing
As seen in igure 1.1.20, the double-volute casing develops a constant low radial reaction orce at any capacity. Return channels (igure 1.1.21) are used in multistage pumps and have the same unction as volute casings. Liquid is led rom one impeller to the next. At the same time, water rotation is reduced and the dynamic pressure is transormed into static pressure. Because o the return channel casing’s circular design, no radial orces are present.
Fig. 1.1.21: Vertical multistage in-line pump with return channel casing Return channel
1.1.7 Single-stage pumps Generally, single-stage pumps are used in applications that do not require a total head o more than 450 t. Normally, single-stage pumps operate in the range o 6-300 t. Single-stage pumps are characterized by a low head relative to the low, see igure 1.1.3. Single-stage pumps come in both a vertical and horizontal design, see igures 1.1.22 and 1.1.23.
Fig. 1.1.22: Horizontal single-stage end-suction close-coupled pump
Fig. 1.1.23: Vertical single-stage in-line close-coupled pump
Section 1.1 Pump construction
1.1.8 Multistage pumps Multistage pumps are used in installations where a high head is needed. Several stages are connected in series and the low is guided rom the outlet o one stage to the inlet o the next. The inal head that a multistage pump delivers is equal to the sum o the pressure that each o the stages provide.
Close-coupled pumps These pumps can be constructed as ollows: The pump’s impeller can be mounted directly on the extended motor shat or the pump can have a standard motor and a rigid or a spacer coupling, see igures 1.1.28 and 1.1.29.
Multistage pumps provide high head relative to the low and have a steeper curve that is more advantageous or variable speed drive, also known as variable requency drive (VFD) applications. Like the single-stage pump, the multistage pump is available in both vertical and horizontal versions, see igures 1.1.24 and 1.1.25.
Horizontal, Multistage Pumps This type o pump is somewhat unique. With the same beneits mentioned in 1.1.8, horizontal multistage pumps meet low and head requirements o single-stage end-suction pumps but with signiicant reductions in required horsepower. In general, multistage pumps oer higher eiciencies when compared to single-stage end-suction pumps resulting in energy savings. Due to design, horizontal multistage pumps do not encounter the same vibration problems oten associated with single-stage end-suction pumps.
Fig. 1.1.24: Vertical multistage in-line pump
Fig. 1.1.25: Horizontal multistage end-suction pump
Fig. 1.1.26: Long-coupled pump with basic coupling
Fig. 1.1.27: Long-coupled pump with spacer coupling
1.1.9 Long-coupled and close-coupled pumps Long-coupled pumps Long-coupled pumps have a lexible coupling (basic or spacer) that connects the pump and the motor. I the pump is connected to the motor by a basic coupling, the motor must be disconnected when the pump is serviced. The pump must thereore be aligned upon mounting, see igure 1.1.26. I the pump is itted with a spacer coupling, the pump can be serviced without removing the motor and alignment is less o an issue, see igure 1.1.27.
Fig. 1.1.28: Close-coupled pump with rigid coupling
Fig. 1.1.29: Close-coupled pump with impeller directly mounted on motor shat
Section 1.2 Types o pumps
1.2.1 Standard pumps Few international standards deal with centriugal pumps. In act, many countries have their own standards, which more or less overlap one another. A standard pump is a pump that complies with oicial regulations pertaining to the pump’s duty point. A couple o examples o international standards or pumps ollow: •
Fig. 1.2.1: Long-coupled standard pump
ANSI B73.1 B73.1 standard standard covers covers centriugal centriugal pumps o horizontal end-suction single-stage, centerline design. This standard includes dimensional interchangeability requirements and certain design eatures to acilitate installation and maintenance.
• DIN 24255 applies to end-suction centriugal pumps, also known as standard s tandard water pumps, with a rated pressure (PN) o 145 psi. The standards mentioned above cover the installation dimensions and the duty points o the dierent pump types. The hydraulic parts o these pump types vary according to the manuacturer – so, no international standards are set or these parts.
Fig. 1.2.2: Bare shat standard pump
Pumps designed according to standards provide end users with advantages in installation, service, spare parts and maintenance.
1.2.2 Split-case pumps A split-case pump is designed with the pump housing divided axially into two parts. Figure 1.2.4 shows a single-stage split-case pump with a double-suction impeller. The double-inlet construction eliminates the axial orces and ensures a longer lie span o the bearings. Usually, split-case pumps have a rather high eiciency, are easy to service and have a wide perormance range.
Fig. 1.2.3: Long-coupled split-case pump
Fig. 1.2.4: Split-case pump with double-suction impeller
Section 1.2 Types o pumps
1.2.3 Hermetically sealed pumps
Liquid Seal Atmosphere
The penetration point o the pump liquid by the shat that allows it to connect to the impeller has to be sealed. Usually, this is addressed by a mechanical shat seal, see igure 1.2.5. The disadvantage o the mechanical shat seal is its poor handling o toxic and aggressive liquids, which consequently leads to leakage. This problem can oten be solved by using a double mechanical shat seal. Another solution is to use a hermetically sealed pump. There are two types o hermetically sealed pumps: Canned motor pumps and magnetic-driven pumps. In the ollowing two sections, additional inormation about these pumps is provided. A disadvantage o hermetically sealed pumps is that they can handle very little, i any, solids in the pumped liquid.
Canned motor pumps A canned motor pump is a hermetically sealed pump with the motor and pump integrated in one unit without a seal, see igures 1.2.6 and 1.2.7. The pumped liquid is allowed to enter the rotor chamber that is separated rom the stator by a thin rotor can. The rotor can serves as a hermetically sealed barrier between the liquid and the motor. Chemical pumps are made o materials, such as plastics or stainless steel, that can withstand aggressive liquids.
Fig. 1.2.5: Example o a standard pump with mechanical shat seal
Motor can
Fig. 1.2.6: Chemical pump with canned motor
Motor can
The most common canned motor pump type is the circulator pump. This type o pump is typically used in heating or cooling applications because the construction provides low noise and maintenanceree operation.
Fig. 1.2.7: Circulator pump with canned motor
Magnetic-driven Magnetic-dri ven pumps In recent years, magnetic-driven pumps have become increasingly popular or transerring aggressive and toxic liquids. As shown in igure 1.2.8, the magnetic-driven pump is made o two groups o o magnets: An inner magnet and an outer magnet. A non-magnetic can separate these two magnets. The can serves as a hermetically sealed barrier between the liquid and the atmosphere. As it appears rom igure 1.2.9, the outer magnet is connected to the pump drive and the inner magnet is connected to the pump shat. The torque rom the pump drive is transmitted to the pump shat by means o attraction between the inner and outer magnets. The pumped liquid serves as lubricant or the bearings in the pump. Thereore, suicient venting is crucial or the bearings.
Outer magnets
Inner magnets
Can
Fig. 1.2.8: Construction o magnetic drive
Inner magnets Can Outer magnets
Fig. 1.2.9: Magnetic-driven multistage pump
Section 1.2 Types o pumps
1.2.4 Sanitary pumps Sanitary pumps are mainly used in ood, beverage, pharmaceutical and bio-technological industries where liquid is pumped gently and pumps are easy to clean using clean-in-place (CIP) techniques. In order to meet process requirements in these industries, the pumps have to have a surace roughness less than 32 µ-in (0.8 µ-m) or better. This can be best achieved by using orged or deep-drawn rolled stainless steel as the material o construction, see igure 1.2.12. 1.2.12. These materials have a compact pore-ree surace inish that can be easily worked up to meet the various surace inish requirements. The U.S. recommended interior surace inishes range rom 32 µ-in or ood and beverage applications down to 10 µ-in or bioprocessing applications.
Fig. 1.2.10: Sanitary pump
The main eatures o a sanitary pump are ease o cleaning and ease o maintenance. The leading U.S. manuacturers o sanitary pumps have designed their products to meet the material speciications o the U.S. Food and Drug Administration (FDA) and the voluntary standards developed by 3-A Sanitary Standards Inc., as well as other well known globally-recognized standards such as:
Fig.1.2.11:: Sanitary sel-priming side-channel pump Fig.1.2.11
EHEDG – European Hygienic Engineering Design Group QHD – Qualiied Hygienic Design Sand casting
Precision casting
Rolled steel Fig.1.2.12: Roughness o material suraces
1.2.5 Wastewater pumps Wastewater pumps can be classiied as submersible and dry pit pumps. In submersible installations with sliderail systems, double rails are normally used. The auto-coupling system acilitates maintenance, repair and replacement o the pump. It is not necessary to enter the pit to perorm service. In act, it is possible to connect and disconnect the pump automatically rom the outside o the pit. Wastewater pumps can also be installed dry, like conventional pumps, in vertical or horizontal installations. installation s. This type o installation provides easy maintenance and repair as well as uninterrupted operation o the pump in case o looding o the dry pit, see igure 1.2.14. Normally, wastewater pumps must be able to handle large particles (i.e. 3-inch solids) and are itted with special impellers to avoid blockage and clogging. Dierent types o impellers include: Single-channel impellers, double-channel impellers, three and ourchannel impellers and vortex impellers. Figure 1.2.15 shows the dierent designs o these impellers.
Fig. 1.2.13: Detail o a sewage pump or wet installations
Fig. 1.2.14: Wastewater pump or dry installations
Wastewater pumps with submersible motors shall carry the Underwriters Laboratories Inc label or class I, Divison I, Group D environment. Submersible wastewater pump motors are hermetically sealed and have a common extended shat with a tandem mechanical shat seal system in an intermediate oil chamber, see igure 1.2.13. Wastewater pumps are able to operate either intermittently or continuously, depending on the installation in question.
Vortex impeller
Single-channel impeller
Fig. 1.2.15: Impeller types or wastewater
Double-channel impeller
Section 1.2 Types o pumps
1.2.6 Immersible pumps An immersible pump is a pump type where the pump part is immersed in the pumped liquid and the motor is kept dry. Normally, immersible pumps are mounted on top o or in the wall o tanks or containers. Immersible pumps are used in the machine tool industry, in chip conveyor systems, grinding machines, machining centers, cooling units or in other industrial applications involving tanks or containers, such as industrial washing and iltering systems. Pumps or machine tools can be divided into two groups: Pumps or the clean side o the ilter and pumps or the dirty side o the ilter. Pumps with closed impellers are normally used or the clean side o the ilter because they provide a high eiciency and a high pressure i necessary. Pumps with open or semi-open impellers are normally used or the dirty side o the ilter because they can handle metal chips and particles. Reer to page 14 or more dis cussion on impeller types.
Fig. 1 .2.16: Immersible pump
1.2.7 Groundwater pumps There are two primary types o pumps used or groundwater applications: The submersible turbine pump type, which eatures a pump directly attached to a submersible motor and are completely submerged in the groundwater, and the line shat turbine pump type with a motor mounted at the top o the well which is connected to the submerged pump by a long shat. Both pump types are used to pump groundwater rom a well, typically or water supply and irrigation. Because these pump types must it into deep, narrow wells, they have a reduced diameter compared to above-ground pumps making them long and thin compared to most other pump types. Submersible turbine pumps are specially designed to be itted to a submersible motor, and the entire assembly is submerged in a liquid. The submersible motor is sealed to prevent water intrusion, and generally no regular maintenance is required on these pumps. Submersible pumps are preerred in deep installations and those requiring low to medium low rates, generally up to 2,500 GPM. The liquid surrounding the submersible motor cools it, so submersible pumps are not suitable or hot water applications. Line shat turbine pumps have been replaced in many applications by submersible turbine pumps but are preerred or certain applications such as shallow wells and those applications requiring higher low rates. The long shat is a drawback in deep settings making installation diicult and requiring requent service. Because the line shat turbine’s motor is aircooled, it is oten used in industrial applications to pump hot water.
A
B
Fig. 1.2.17: Submersible turbine pump (A) and Line s hat turbine (B)
Section 1.2 Types o pumps
1.2.8 Positive displacement pumps
Fig. 1.2.19: Typical relation between low and head or 3 dierent pump types: 1) Centriugal pumps 2) Rotary pumps 3) Reciprocating pumps
H
The positive displacement pump provides an approximate constant low at ixed speed, despite changes in the back pressure. Two main types o positive displacement pumps include:
1 H
• Rotary pumps • Reciprocating pumps The dierence in perormance between centriugal, rotary and reciprocating pumps is illustrated in igure 1.2.19. Depending on the pump type, a small change in the pump’s back pressure results in dierences in the low. The low o a centriugal pump will change considerably with back pressure. Changing back pressure on rotary pumps will result in a minimal low change. However, the low o the reciprocating pump is almost constant with the back pressure change. The perormance dierence between reciprocating pumps and rotary pumps is due to the rotary pump’s larger seal surace area. Even though the two pumps are designed with the same tolerances, the loss due
Fig. 1.2.18: Rotary Lobe pump
3
2
2
1
Q
to the larger seal area o the rotary pump is greater. The pumps are typically designed with the inest tolerances possible to obtain the highest possible eiciency and suction capability. However, in some cases, it is necessary to increase the tolerances, or example, when the pumps must handle highly viscous liquids, liquids containing large particles or liquids o high temperature.
Metering pumps The metering pump belongs to the positive displacement pump amily and is typically o the diaphragm type. Diaphragm pumps are leak-ree, because the diaphragm orms a seal between the liquid and the surroundings.
electrical parts caused by the solenoid operation, stepper motor-driven diaphragm pumps enable a more steady dose o additive.
The diaphragm pump is usually itted with two or three non-return valves; one or two on the suction side and one on the discharge side o the pump. On smaller diaphragm pumps, the diaphragm is activated by the connecting rod, which is connected to a solenoid, permitting the coil to receive the exact amount o strokes needed, see igure 1.2.21. On larger diaphragm pumps, the diaphragm is typically mounted on the connecting rod, which is activated by a camshat. The camshat is turned by way o a standard asynchronous motor, see igure 1.2.22. Fig. 1.2.20: Dosing pump
The low o a diaphragm pump is adjusted by b y changing the stroke length and/or the requency o the strokes. I it is necessary to expand the operating area, requency converters can be connected to the larger diaphragm pumps, see igure 1.2.22. Yet another kind o diaphragm pump exists. In this case, the diaphragm is activated by means o an eccentrically driven connecting rod powered by a stepper motor or a synchronous motor, igures 1.2.20 and 1.2.23. A stepper motor drive increases the pump’s dynamic range, thus improving its accuracy. This construction no longer requires stroke length adjustment because the connecting rod is mounted directly on the diaphragm. The result is optimized suction and operation due to ull suction. Stepper motor drive design simpliies control o both the suction side and the discharge side o the pump. Compared to traditional electromagneticdriven diaphragm pumps which provide undesirable pulsations as well as ast wearing o mechanical and
Fig.1.2.21: Solenoid spring return +
1.2.22: Cam-drive assembly spring return
+
1.2.23: Stepper motor drive
Chapter 1. Design o pumps and motors
Section 1.3: Mechanical shat seals 1.3.1 The mechanical mechanical shat seal’s components components and unction 1.3.2 Types o mechanical shat seals seals 1.3.3 Balanced and and unbalanced unbalanced shat seals 1.3.4 Seal ace ace material material combinations combinations 1.3.5 Factors aecting aecting the seal perormance perormance
Section 1.3 Mechanical shat seals
From the middle o the 1950s, mechanical shat seals gained ground in avor o the traditional sealing method - the stuing box. Compared to stuing boxes, mechanical shat seals provide the ollowing advantages:
• None or minimal leakage o the luid being pumped.
• No adjustment required • Seal aces provide a small amount o riction, minimizing power loss
• The shat does not slide against any o the seal’s components and thereore reduces wear and associated repair costs. The mechanical shat seal is the part o a pump that separates the liquid rom the atmosphere. Figure 1.3.1 illustrates mechanical shat seal mounting in dierent types o pumps. Beore choosing shat seal material and type, consider the ollowing:
• Determine the type o liquid • Determine the pressure that the shat seal is exposed to
• Determine the speed that the shat seal is exposed to
• Determine the shat-seal housing dimensions The ollowing pages present how a mechanical shat seal works, the dierent types o seals, materials used in mechanical shat seals, and the actors that aect the mechanical shat seal’s perormance.
Fig. 1.3.1: Pumps with mechanical shat seals
1.3.1 The mechanical shat seal’s components and unction The mechanical shat seal is made o two main components: A rotating part and a stationary part. The parts o a shat seal are listed in igure 1.3.2. Figure 1.3.3 shows where the dierent parts are placed in the seal.
• The stationary component o the seal is ixed in the pump housing. The rotating component o the seal is ixed on the pump shat and rotates when the pump operates. • The two primary seal aces are pushed against each other by the spring (or other devices such as a metal bellows) and the liquid pressure. During operation, a liquid ilm is produced in the narrow gap between the two seal aces. This ilm evaporates beore it enters the atmosphere making the mechanical shat seal leak-ree, see igure 1.3.4.
• The hydrodynamic lubricating ilm is created by pressure generated by the shat’s rotation.
Mechanical shaft seal
Designation
Seal face (primary seal) Secondary seal Rotating component Spring Spring retainer (torque transmission) Stationary component
Seat (seal faces, primary seal) Static seal (secondary seal)
Fig. 1.3.2: The mechanical shat seal’s components
Spring
Secondary seal Primary seal
Stationary part Rotating part
Spring retainer
Shat
• Secondary seals prevent leakage rom occurring between the assembly and the shat. Secondary seal
• The spring or metal bellows press the seal aces together mechanically. • The spring retainer transmits torque rom the shat to the seal. In connection with mechanical bellows shat seals, torque is transerred directly through the bellows.
Fig. 1.3.3: Main components o the
Primary seal
mechanical shat seal
Vapor
Evaporation begins
Lubrication ilm Liquid orce Spring orce
Seal gap During operation, the liquid orms a lubricating ilm between the seal aces. This lubricating ilm consists o a hydrostatic and a hydrodynamic ilm.
• The hydrostatic element is generated by the pumped liquid which is orced into the gap between the seal aces.
Fig. 1.3.4: Mechanical shat seal in operation
Section 1.3 Mechanical shat seals
Start of evaporation 1 atm
Exit into atmosphere
1.3.2 Balanced and unbalanced shat seals To obtain an acceptable ace pressure between the primary seal aces, two kinds o seal types exist: A balanced shat seal and an unbalanced shat seal.
Balanced shat seal Stationary seal face
Rotating seal face Pump pressure
Entrance in seal
Pressure Liquid
Vapor
Atmosphere
Fig. 1.3.5: Optimum ratio between ine lubrication properties and limited leakage
The thickness o the lubricating ilm depends on the pump speed, the liquid temperature, the viscosity o the liquid and the axial orces o the mechanical shat seal. The The liquid in the seal gap is continuously renewed due to:
• evaporation o the liquid to the atmosphere • Recirculation o the liquid Figure 1.3.5 shows the optimum ratio between ine lubrication properties and limited leakage. The optimum ratio occurs when the lubricating ilm covers the entire seal gap, except or a very narrow evaporation zone close to the atmospheric side o the mechanical shat seal. Deposits on the seal aces may cause leakage. When using coolant agents, deposits build up quickly rom evaporation at the atmosphere side o the seal. When the liquid evaporates in the evaporation zone, microscopic solids in the liquid remain in the seal gap as deposits, causing wear. These deposits are seen with most types o liquid. When the pumped liquid crystallize crystallizes, s, it can become a problem. The best way to prevent wear is to select seal aces made o hard material such as WC (tungsten carbide) or SiC (silicon carbide). The narrow seal gap between these materials (approx. Ra 0.3 µin) minimizes the risk o solids entering the seal gap, resulting in less buildup o deposits.
Figure 1.3.6 shows a balanced shat seal indicating where the orces impact on the seal.
Unbalanced shat seal Figure 1.3.7 shows an unbalanced shat seal indicating where the orces impact the seal.
Contact area o seal aces Contact area o seal aces Spring orces
Hydraulic orces
Hydraulic orces
A
B
Fig. 1.3.6: Impact o orces on the balanced shat seal
A
B
Fig. 1.3.7: Impact o orces on the unbalanced shat seal
Several dierent orces have an axial impact on the seal aces. The spring and the hydraulic orces rom the pumped liquid press the seal together while the orce rom the lubricating ilm in the seal gap counteracts this. With high liquid pressure, the hydraulic orces can be so powerul that the lubricant in the seal gap cannot counteract the contact between the seal aces. Because the hydraulic orce is proportionate to the area that the liquid pressure aects, the axial impact can only be reduced by obtaining a reduction o the pressure-loaded area. The balancing ratio (K) o a mechanical shat seal is
deined as the ratio between the area A and the area B : K=A/B
Comparative wear rates valid for water
K = 1.15 K = 1.00 K = 0.85
K = Balancing ratio A = Area exposed to hydraulic pressure B = Contact area o seal aces The balancing ratio or balanced shat seals is around K=0.8 and or unbalanced shat seals is around K=1.2.
1.3.3 Types o mechanical shat seals
68
104
1 40
212
230
Temperature (oF)
Fig. 1.3.8: Wear rate or dierent balancing ratios
The main types o mechanical shat seals include: Oring, bellows, cartridge single-unit seal.
Advantages and disadvantages o O-ring seal
O-ring seals Sealing between the rotating shat and the rotating seal ace is aected by an O-ring’s movement (see igure 1.3.9). The O-ring must be able to slide reely in the axial direction to absorb axial displacements as a result o changes in temperature and wear. Incorrect positioning o the stationary seat may result in rubbing, which can cause wear on the O-ring and shat. O-rings are made o dierent types o rubber material, such as NBR, EPDM, Buna -N and FKM, depending on operating conditions.
1 76
Advantages: Suitable in hot liquid and high pressure applications Disadvantages: Deposits on the shat, such as rust, may prevent the O-ring shat seal rom moving axially causing leakage and premature ailure Fig. 1.3.9: O-ring seal
Bellows seals Common to bellows seals is a rubber or metal bellows bellows which unctions as a dynamic sealing element between the rotating ring and the shat.
Rubber bellows seal with olding bellows geometry
Advantages and disadvantages o rubber bellows seal
Rubber bellows seals The bellows o a rubber bellows seal (see igure 1.3.10) can be made o dierent types o rubber, such as NBR, EPDM, Buna-N and FKM, depending on the operating conditions. Two designs are used or rubber bellows:
Advantages: Not sensitive to deposits, such as rust, on the shat Suitable or pumping solid-containing solid-contai ning liquids
• Folding bellows • Rolling bellows
Disadvantages: Not suitable in hot liquid and high pressure applications Fig. 1.3.10: Rubber bellows seal
Section 1.3 Mechanical shat seals
Metal bellows seals
Advantages and disadvantages o cartridge metal bellows seal
In an ordinary mechanical shat seal, the spring produces the closing orce required to close the seal aces. In a metal bellows seal, the spring is replaced by a metal bellows with a similar orce (see igure 1.3.11). Metal bellows act both as a dynamic seal between the rotating ring and the shat and as a spring. The bellows have a number o corrugations to provide the desired spring orce.
Advantages: Not sensitive to deposits, such as rust and lime, on the shat Suitable in hot liquid and high-pressure applications
Fig. 1.3.11: Cartridge metal bellows seal
Low balancing ratio leads to low wear rate and consequently longer lie Disadvantages: Fatigue ailure o the mechanical shat seal may occur when the pump is not aligned correctly Fatigue may occur as a result o excessive temperatures or pressures
Cartridge seals In a cartridge mechanical shat seal, all parts orm a compact unit on a shat sleeve and are ready to be installed. A cartridge seal oers many beneits compared to conventional mechanical shat seals, see igure 1.3.12.
Advantages o the cartridge seal: • Easy and ast service • The design protects the seal aces • Preloaded spring • Sae handling
Flushing In certain applications it is possible to extend the perormance o the mechanical shat seal by installing a lushing device, see igure 1.3.13. Flushing can lower the temperature o the mechanical shat seal and prevent deposits rom occurring. A lushing device can be installed internally or externally. Internal lushing is done when a small low rom the pump’s discharge side is bypassed to the seal area. Internal lushing is primarily used to prevent urther heat generation rom the seal in heating applications. External lushing is done by a lushing liquid and is used to ensure trouble-ree operation when handling liquids that are abrasive or contain clogging solids.
Fig. 1.3.12: Cartridge seal
Fig 1.3.13: Flushing device o a single mechanical shat seal
Double mechanical shat seals Double mechanical shat seals are used when the lie span o a single mechanical shat seal is insuicient due to wear caused by solids, or too high/low pressure and temperature. Double mechanical shat seals help protect the surroundings when aggressive and explosive liquids are pumped. Two types o double mechanical shat seals include: The double seal in a tandem arrangement and the double seal in a back-to-back arrangement.
Quench liquid
•
Pumped liquid
•
Double seal in tandem This seal consists o two mechanical shat seals mounted in tandem, one behind the other, and placed in a separate seal chamber, see igure 1.3.14. The tandem seal arrangement must be itted with an external barrier liquid system which:
• Absorbs leakage • Monitors the leakage rate • Lubricates and cools the outboard seal to prevent icing • Protects against dry-running • Stabilizes the lubricating ilm • Prevents air rom entering the pump in case o vacuum Pressure o the external barrier liquid must always be lower than the pumped liquid pressure.
•
•
Fig. 1.3.14: Tandem seal arrangement with external barrier •
•
liquid circulation
Quench liquid
•
•
•
Pumped liquid
•
•
•
Fig. 1.3.15: Tandem seal arrangement with external barrier liquid dead end
Tandem - circulation For external barrier liquid circulation via a pressureless tank, see igure 1.3.14. External barrier liquid rom the elevated tank circulates by thermosiphon action and/or by the pumping action in the seal. •
•
Tandem - dead end For external barrier liquid rom an elevated tank, see igure 1.3.15. No heat is dissipated rom the system.
Tandem - drain The external barrier liquid runs through the seal chamber to be collected or reuse or directed to drain, see igure 1.3.16.
•
•
Pumped liquid
•
•
Fig. 1.3.16: Tandem seal arrangement with external barrier liquid to drain
Section 1.3 Mechanical shat seals
Barrier pressure liquid
Seal chamber with barrier pressure liquid
industrial applications: Tungsten carbide/tungsten carbide, silicon carbide/silicon carbide and carbon/tungsten carbide or carbon/silicon carbide.
Tungsten carbide/tungsten carbide Pumped liquid
•
Fig. 1.3.17: Back-to-back seal arrangement
Double seal in back-to back-to-back -back This type o seal is the optimum solution or handling abrasive, aggressive, explosive or sticky liquids which would wear out, damage or block a mechanical shat seal. The back-to-back double double seal consists o two shat seals mounted back-to-back in a separate seal chamber, see igure 1.3.17. The back-to-back double seal protects the surrounding environment and the people working with the pump. The pressure in the seal chamber must be 14.5-29 psi higher than the pump pressure. The pressure can be generated by:
• An existing, separate pressure source. Many applications incorporate pressurized systems. • A separate pump, e.g. a metering pump
1.3.4 Seal face material combinations What ollows is a description o the most important material combinations used in mechanical shat seals or
Cemented tungsten carbide covers the type of hard metals that are based on a hard tungsten carbide (WC) phase and usually a softer metallic binder phase. The correct technical term is cemented tungsten carbide; however, the abbreviated term tungsten carbide (WC) is used by Grundfos for convenience. Cobalt-bonded (Co) WC is only corrosion resistant in water if the pump incorporates base metal, such as cast iron. Chromium-nickel-molybdenum-bonded WC has a higher corrosion resistance. Sintered binderless WC has the highest corrosion resistance. However, its resistance to corrosion in liquids, such as hypochlorite, is not as high. The material pairing WC/WC has the ollowing eatures:
• Extremely wear resistant • Very robust; resists rough handling • Poor dry-running properties. In case of dry-running, the temperature increases to several hundred degrees Fahrenheit in just a few minutes and consequently damages the O-rings. I a certain pressure and temperature are exceeded, the seal may generate noise. Noise is an indication o poor seal operating conditions that, in the long term, may cause wear o the seal. The limits o use depend on seal ace diameter and design. A WC/WC seal ace pair might be noisy during the break in period. Usually the noise dissapears ater a couple o days o operation. In some cases noise may last up to 3-4 weeks.
Silicon carbide/silicon carbide Silicon carbide/silicon carbide (SiC/SiC) is an alternative to WC/WC and is used where higher corrosion resistance is required.
In warm water, the Q 1P / Q 1P ace material pair generates less noise than the WC/WC pair; however, noise rom porous SiC seals must be expected during the running-in wear period o 3-4 days. Q 1G self-lubricating, sintered SiC
The SiC/SiC material pair has the ollowing eatures:
• Very brittle material requiring careul handling • Extremely wear resistant
Several variants o SiC materials containing dry lubricants are available on the market. The designation Q 1G applies to a SiC material which is suitable or use in distilled or demineralized water, as opposed to the above materials.
• High resistance to corrosion. SiC (Q 1s, Q 1P and Q 1G ) hardly corrodes, independent o the pumped liquid type with the exception o water with very poor conductivity, such as s demineralized water, which attacks the SiC variants Q 1 and Q 1P. Q 1G is also corrosion - resistant in demineralized water
Pressure and temperature limits o Q 1G / Q 1G are similar to those o Q 1P / Q 1P.
• In general, these material pairs have poor dry-running properties. However, the Q 1G / Q 1G material withstands a limited period o dry-running due to the graphite content o the material
Carbon/tungsten carbide or carbon/ silicon carbide features
For dierent purposes, SiC/SiC variants include: Q 1s, dense-sintered, fine-grained SiC
The dry lubricants, such as graphite, reduce the riction in case o dry-running and are critical to the durability o a seal during dry-running.
Seals with one carbon seal ace have the ollowing eatures:
• Brittle material requiring careul handling • Are worn by liquids containing solid particles
A dense-sintered, ine-grained SiC with a small amount o tiny pores. For a number o years, this SiC variant was used as a standard mechanical shat seal material. Pressure and temperature limits are slightly below those o WC/WC. Q 1P, porous, sintered, fine-grained SiC This porous-sintered SiC variant has large circular closed pores. The degree o porosity is 5-15% and the size o the pores is Ra 10-50 µin. The pressure and temperature limits exceed those of WC/WC.
• Good corrosion resistance • Good dry-running properties (temporary dry-running) • Sel-lubricating properties (o carbon) make the seal suitable or use even with poor lubricating conditions (high temperature) without generating noise. However, such conditions will cause wear o the carbon seal ace leading to reduced seal lie. The wear depends on pressure, temperature, liquid diameter and seal design. Low speeds reduce the lubrication between the seal aces resulting in possible increased wear However, since the distance that the seal aces have to move is reduced, a shorter seal lie may not be experienced
Section 1.3 Mechanical shat seals
• Metal-impregnated carbon (A) oers limited corrosion resistance, but improved mechanical strength and heat conductivity, thus reducing wear
• The centriugal pumping pumping action o the seal’s seal’s rotating parts increases power consumption dramatically with the speed o rotation (to the third power)
• With reduced mechanical strength, but higher corrosion resistance, synthetic resin-impregnated carbon (B) covers a wide application ield. Synthetic resin-impregnated carbon is suitable or drinking water
• The seal ace riction Friction between the two seal aces consists o – riction in the thin liquid ilm and – riction due to points o contact between the seal aces
• The use of carbon/SiC for hot water applications may cause heavy wear o the SiC, depending on the quality o the carbon and water. This type o wear primarily applies to Q1 S/carbon. The use o Q1 P, Q 1G or a carbon/WC pair causes ar less wear. Thus, P G carbon/WC, carbon/Q1 or carbon/Q1 are recommended or hot water systems
The amount o power consumed depends on seal design, lubricating conditions and seal ace materials.
0.25
Power loss (hp)
0.2
0.15
0.1 3600 0.05
1.3.5 Factors affecting the seal performance As mentioned previously, no seal is completely tight. On the next pages, actors which have an impact on the seal perormance, such as energy consumption, noise and leakage, will be presented. While these actors will be presented individually, it is important to stress that they are closely interrelated and should be considered as a whole.
Energy consumption The ollowing actors contribute to the power consumption o a mechanical shat seal:
0 0
2000
4000
6000
8000
10000
12000
Speed (rpm)
Fig. 1.3.18: Power consumption o a 1/2 inch mechanical shat seal
Pumping action Friction
Figure 1.3.18 is a typical example o the power consumption o a mechanical shat seal. The igure shows that up to 3600 rpm riction is the major reason or the mechanical shat seal’s energy consumption. c onsumption.
Energy consumption is, especially in connection with packed stuing box, an important issue. Replacing a stuing box with a mechanical shat seal leads to considerable energy savings, see igure 1.3.19.
Standard pump 50 ft WCH; 2 inch shaft Energy consumption
Stuffing box 2.0 kwh Mechanical shaft seal 0.3 kkwh wh Leakage
Noise The choice o seal ace materials is critical or the unction and the lie o the mechanical shat seal. Noise is generated as a result o the poor lubricating conditions in seals handling low viscosity liquids. The viscosity o water decreases with increasing temperature. This means that the lubricating conditions decrease as the temperature rises. I the pumped liquid reaches or exceeds boiling temperature, the liquid on part o the seal ace evaporates resulting in decreased lubricating conditions. A speed reduction has the same eect, see igure 1.3.20.
Stuffing box .02 GPD (when mounted correctly) Mechanical shaft seal .005 GPD Fig. 1.3.19: Stuing box versus mechanical shat seal
psi 350
300
Noise
Duty range
250
200
Speed at 3600 rpm
150
Speed at 3000 rpm
100
Speed at 1800 rpm 50
Leakage
Speed at 1200 rpm
0 0
75
50
100
125
150
175
200
225 22
°F
Fig. 1.3.20: Relationship between duty range and speed
The pumped liquid lubricates the seal ace o a mechanical shat seal, providing improved lubrication resulting in less riction and increased leakage. Conversely, less leakage means poor lubricating conditions and increased riction. In practice, the amount o leakage and power loss occurring in mechanical shat seals can vary because leakage depends on actors which are impossible to quantiy theoretically due to seal ace type, liquid type, and spring load.
Exit into atmosphere
1 atm
Start of evaporation
Figure 1.3.21 shows how the lubricating ilm o luid is evaporated into the atmosphere. Stationary seal face
Rotating seal face
Pump pressure
Fig. 1.3.21: Sealing gap
Pressure liquid
Entrance in seal vapor
Atmospheric
Chapter 1. Design o pumps and motors
Section 1.4: Motors 1.4.1 1.4.2 1.4.3 1.4.4 1.4.5
Standards Motor start-up Voltage supply Frequency converter Motor protection
Section 1.4 Motors
Motors are used in many applications all over the world. The purpose of the electric motor is to create rotation, that is to convert electric energy into mechanical energy. Pumps are operated by means of mechanical energy which is provided by electric motors.
Fig. 1.4.1: Electric motor
1.4.1 Standards
Fig. 1.4.2: NEMA and IEC standards
NEMA
IEC
The National Electrical Manufacturers Association (NEMA) sets standards for a wide range of electric products, including motors. NEMA is primarily associated with motors used in North America. The standards represent general industry practices and are supported by the manufacturers of electric equipment. The standards can be found in NEMA Standard Publication No. MG1. Some large motors may not fall under NEMA standards.
The International Electrotechnical Commission (IEC) sets standards or motors used in many countries around the world. The IEC 60034 standard contains recommended electrical practices that have been developed by the participating IEC countries.
Introduction to potentially explosive atmospheres
Area Classification Process plants are divided into Divisions (North American method) or Zones (European and IEC method) according to the likelihood o a potentially explosive atmosphere being present. Note: North American legislation now allows Zones to classiy areas, and when used, the IEC Zone method is ollowed. See igure 1.4.3.
Potentially explosive atmospheres exist where there is a risk o explosion due to mixtures o gas/air, vapor/ air, dust/air or other lammable combinations. In such areas there is a need to eliminate ignition sources sourc es such as sparks, hot suraces or static electricity which may ignite these mixtures. When electrical equipment is used where there is risk o explosion, the area must be so designed and constructed to avoid sources o ignition capable o igniting these mixtures. Beore electrical equipment can be used in a potentially explosive atmosphere, a represenative sample must be ully tested and certiied by an independent authority such as UL in the U.S.A. This inormation is intended as a guide guid e only, and urther expert guidance should be sought beore placing the equipment into service or beore maintaining or repairing any item o equipment in a potentially explosive atmosphere. Where showing comparisons, i.e., North American and European practices, these may be approximations and individual standards/codes o practice should be observed or precise details. European & IEC Classification
Gas Groups (plus dusts and ibers) There are two main gas groups: Group I - Mining only and Group II - Surace Industries. These categories are used in European and I.E.C. groupings. Group I gases relate to underground mining where methane and coal dust are present. Group II gases relate to surace industries and are sub-grouped according to their volatility. This enables electrical equipment to be designed with less onerous tolerances i it is to be used with the least volatile gases. See igure 1.4.4.
Definition of zone or division
Nor th American Classification
Zone 0 (gases) Zone 2 0 (dusts)
A n area in which an explosive mixture is continuous y l present or present f or long periods
C la ss I Division 1 (gases) C la ss II Division 1 (dusts)
Zone 1 (gases) Zone 2 1 (dusts)
A n area in which an explosive mixture is likel y to occur in norma l opera tion
C la ss I Division 1 (gases) C la ss II Division 1 (dusts)
Zone 2 (gases) Zone 2 2 (dusts)
A n a rea in which an explosive mixture is not like y l to occur in normal operation a nd if it occurs it will exist only for a short time
C la ss I Division 2 (ga ses) C la ss II Division 2 (dusts) Class III Division 1 (fibers) Class III Division 2 (fibers)
Fig. 1.4.3: Area Classiicatio Classiication n
T ypica l ga s / ma teria l Metha ne A cet ylene H ydrogen Eth ylene Propane
N or th A merica n G as Group -
Europea n / I.E.C . G as G roup
A
IIC
B
IIC
I
C
IIB
D
IIA
E
-
C oa l dust
F
-
G ra in dust
G
-
Meta l dust
Fig. 1.4.4: Gas Groups
Section 1.4 Motors
Types o electrical equipment suitable or use in potentially explosive atmospheres Dierent techniques are used to prevent electrical equipment rom igniting explosive atmospheres. See ig 1.4.5 or restrictions as to where these dierent types o equipment can be used. Flameproof Enclosure – An enclosure used to house electrical equipment which, when subjected to an internal explosion, will not ignite a surrounding explosive a tmosphere. Intrinsic Safety– A technique whereby electrical energy is limited such that any sparks or heat generated by electrical equipment equipment is suf f icient y l low as to not ignite an explosive atmosphere.
USA Area of use Designation Standard Class I Divisions 1 & 2 – UL1203
IEC Area of use Designation Standard Zones 1 & 2
Class I Divisions 1 & 2 –
Zones 1 & 2
Zones 0, 1 & 2
Exi IEC60079-11 Zones 1 &2 Exi IEC 6007 9-7 Zones 1 & 2
EExi EN50020 Zones 1 & 2 EExe EN 5 001 9 Zones 1 & 2
UL1203
Increased Safety – This equipment is so designed as to eliminate spa rks a nd hot surf a ces capable of igniting an explosive atmosphere. Purged and Pressurized – Electrical equipment is housed in an enclosure which is initially purged to remove any explosive mixture then pressurizedto prevent ingress of the surrounding atmosphere prior to energization. Encapsulation – A method of exclusion of the explosive atmosphere by fully encapsulating the electrical components in an approved ma terial. Oil Immersion – The electrical components are immersed in oil, thus excluding the explosive atmosphere from any sparks or hot surf aces.
– – – Class l
Divisions 1 & 2 – NFPA 496
– – – Class l
Division 2 – UL698
Exd IEC60079-1
European Area of use Designation Standard Zones 1 & 2
EExd EN50018
Exp IEC 6007 9-2 Zone 1 & 2
EExp EN 5 001 6 Zones 1 & 2
Exm EC 6007 9-1 8 Zones 1 & 2
EExm EN 5 002 8 Zone 1 & 2
Exo EC 6007 9-6 Zones 1 & 2
EExo EN50015 Zones 1 & 2 EExq EN 5 001 7 Zone 2 EExN EN50021 Zones 0, 1 & 2 *Exs
Powder Filling – Equipment is surrounded with a fine powder, such as quartz, which does not allow the surrounding atmosphere to come into conta ct with an y spa rks or hot surf a ces. Non-sparking – Sparking contacts are sealed against ingress of the surrounding atmosphere;, hot surf a ces are eliminated.
– – – – – –
Special Protection– Equipment is certified for use in a Potentially Explosive Atmosphere but does not conform to a type of protection listed above.
–
Exq IEC 6007 9-5 Zone 2 Exn EC 6007 9-1 5 Zones 0, 1 & 2
–
Exs
Fig 1.4.5: Standards and methods o protection
North American practice Sample equipment and supporting documentation are submitted to the appropriate authority, e.g U.L., F.M., C.S.A. Equipment is tested in accordance with relevant standards or explosion protection and also
or general electrical requirements, e.g. light ittings. Ater successul testing, a listing is issued allowing the manuacturer to place the product on the market. The product is marked with the certiication details such as the gas groups A,B,C,D and the area o use, e.g. Class 1 Division 1.
Temperature Hot suraces can ignite explosive atmospheres. To prevent this rom happening, all electrical equipment intended or use in a potentially explosive atmosphere is classiied according to the maximum surace temperature it will reach while in service. This maximum temperature is normally based on a surrounding ambient temperature o 104° F (40° C). This temperature can then be compared to the ignition temperature o the gas(es) which may come into contact with the equipment and a judgement can be reached as to the suitabillity o the equipment to be used in that area, see igure 1.4.6.
NEMA Motor Enclosures The ollowing describes NEMA Motor Enclosures:
• Open Drip Proo (ODP) Internal an pulls air in, blows it across windings inside motor and exits opposite drive end. Motor is protected rom drops o liquid or particles alling at any angle rom 0-15 degrees.
• TEFC-Totally Enclosed External an pulls air in through an cover and blows it over the exterior (only) surace o the motor. More resistant to the liquid and particles. • Washdown - Totally Enclosed Spray Proo Corrosion-resistant. There can be a HP limit or rolled steel rame motors. Cast Iron inned motors do not meet FDA requirements. • Explosion Proo (xp) Enclosed motor designed to withstand an explosion o a speciied dust, gas or vapor according to explosive environment environm ent standards.
Temperature Classification North America European/IEC T1 T1 T2 T2 T2 A T2 B T2 C T2 D T3 T3 T3 A T3 B T3 C T4 T4 T4A T5 T5 T6 T6
Maximum Surface Temperature
842 ° F 5 7 2° F 5 3 6° F 5 00° F 446° F 41 9° F 3 92 ° F 3 5 6° F 3 2 9° F 3 2 0° F 27 5 ° F 2 4 8° F 21 2° F 185° F
Fig 1.4. 1.4.6: 6:: Temp Temperatu Temperature erature re classiication classiicati classi classiicat class iication ication ion on
and the second digit stands or protection against ingress o water, see igure 1.4.7. Drain holes enable the escape o water entering the starter housing, i.e., through condensation. When the motor is installed in a damp environment, the bottom drain hole should be opened. Opening the drain hole changes the motor’s enclosure class rom IP55 to IP44. First digit
Second digit
Protection against contact and ingress o solid objects
Protection against ingress o water
0 No special protection
0 No special protection
1 The motor is protected against solid objects bigger than 55 mm, e.g. a hand
1 The motor is protected against vertically alling drops o water, such as condensed water
2 The motor is protected against objects bigger than 12 mm, e.g. a inger
2 The motor is protected against vertically alling drops o water, even i the motor is tilted at an angle o 15 degrees
3 The motor is protected against solid objects bigger than 25 mm, i.e. wires, tools, etc. 4 The motor is protected against solid objects bigger than 1 mm, e.g. wires 5 The motor is protected against ingress o dust 6 The motor is completely
3 The motor is protected against water spray alling at an angle o 60 degrees rom vertical 4 The motor is protected against water splashing rom any direction 5 The motor is protected against water being projected rom a nozzle rom any direction
dust-proo 6 The motor is protected against
IEC Motor Enclosures The IP rating states the degrees o protection o the motor against ingress o solid objects and water. The rating is stated by the letters “IP” ollowed by two digits, or example IP55. The irst digit stands or protection against contact and ingress o solid objects,
heavy seas or high-pressure water jets rom any direction
7 The motor is protected when submerged rom 15 cm to 1 m in water or a period speciied by the manuacturer 8 The motor is protected against continuous submersion in water under conditions speciied by the manuacturer
Fig 1.4.7: Two-digit IP enclosure class identiication (IEC)
Section 1.4 Motors
Frame size Figure 1.4.8 gives an overview o the relationship between rame size, shat end, and motor po wer. The igure shows where the dierent values that make up the rame size are measured on the motor. Flanges and shat end comply with NEMA standards or EN 50347 and IEC 60072-1 or IEC. Some pumps have a coupling which requires a smooth motor shat end or a special shat extension which is not deined in the standards.
D
2F Distance between holes
Fig 1.4.8: Frame size
Insulation class Hot-spot overtemperature
The insulation class is deined in the NEMA standard and tells something about how robust the insulation system is relative to motor operating temperatures. The lie o an insulation material is highly dependent on the temperature to which it is exposed. The various insulation materials and systems are classiied into insulation classes depending on their ability to resist high temperatures, see igure 1.4.9.
[°f] 356
15
311
10
266 248
10
Maximum temperature increase
176
Maximum ambient temperatu temperature re
104 10 104 4 10 104 4
221
257
104
B
F
H
Maximum ambient temperature (°F)
Maximum temperatureincrease (°F)
Hot-spot overtemperature (°F)
Maximum windingtemperature (Tmax) ( °F)
B
104
144
18
266
F
104
189
18
311
H
104
225
27
356
Class
Fig 1.4.9: Dierent insulation classes and temperature increases at nominal voltage and load
1 2 Fram e Si ze Shaf t end (C-face motors) diameter [ i n] 42C 0.375 48C 0.5 56C 0.625 66C 0.75 143TC 0.875 145TC 0.875 182TC 1.125 184TC 1.125 213TC 1.375 215TC 1.375 254TC 1.625 256TC 1.625 284TC 1.875 286TC 1.875 284TSC 1.625 286TSC 1.625 324TC 2.125 326TC 2.125 324TSC 1.875 326TSC 1.875 364TC 2.375 365TC 2.375 364TSC 1.875 365TSC 1.875 404TC 2.875 405TC 2.875 404TSC 2.125 405TSC 2.125 444TC 3.375 445TC 3.375 444TSC 2.375 445TSC 2.375
3 Rated power (TEFC Motors) 2-pole 4-pol e 6-pol e 8-pole [HP] [HP] [HP] [HP] In these fractional size motors, specific frame assignments have not been made by horsepower and speed. It is possible for more than one HP and and speed combination to be found f ound in a given frame size. 1.5 1 2 1.5, 2.0 1 3 3 1.5 1 5 5 2 1.5 7.5 7.5 3 2 10 10 5 3 15 15 7.5 5 20 20 10 7. 5 25 15 10 30 20 15 25 30 40 25 20 50 30 25 40 50 60 40 30 75 50 40 60 75 60 50 100 75 60 100 125 150 125 150
Fig 1.4.10: The relationship between rame size and power input
100 125
75 100
Section 1.4 Motors
1.4.2 Motor start-up Methods o starting reerred to in this section include: Direct-on-line starting, star/delta starting, autotransormer starting, sot starter and requency converter starting, see igure 1.4.11. Starting method
Pros
Cons
Direct Dir ect-on -on-li -line ne star startin ting g (DOL) (DOL)
Simple Sim ple and cos cost-e t-eic icien ient. t. Sae starting.
High locked-rotor current.
Star/delta starting (SD) (Y/∆)
Reduction o starting current by a actor o 3.
Current pulses when switching over rom star to delta. Not suitable i the load has a low inertia. Reduced locked-rotor torque.
Auto Au totr tran ans sor ormer mer st star arti ting ng
Redu Re duct ctio ion n o lo lock cked ed-r -rot otor or cu curr rren entt an and d to torq rque ue..
Curr Cu rren entt pu puls lses es wh when en sw swit itch chin ing g r rom om re redu duced ced to u ull ll vo volt ltag age. e. Reduced locked-rotor torque.
Sot starter
"Sot" starting. No current pulses. Less water hammer when starting a pump. Reduction o locked-rotor current as required, typically 2-3 times.
Reduced locked-rotor torque.
Freque Fre quency ncy con conver verter ter sta starti rting ng
No cur curren rentt puls pulses. es. Less water hammer when starting a pump. Reduction o locked-rotor current as required, typically 2 to 3 times. Can be used or continuous eeding o the motor.
Reduced locked-rotor torque. Expensive
Fig 1.4.11: Starting method
Direct-on-line starting
Autotransormer Autotrans ormer starting
As the name suggests, direct-on-line starting (DOL) means that the motor is started by connecting it directly to the supply at rated voltage. Direct-online starting is suitable or stable supplies as well as mechanically sti and well-dimensioned shat systems, i.e. pumps. Whenever applying the directon-line starting method, it is important to consult local authorities.
As the name states, autotransormer starting makes use o an autotransormer. The autotransormer is placed in series with the motor during start and varies the voltage up to nominal voltage in two to our steps.
Star/delta starting The objective o this starting method, which is used with three-phase induction motors, is to reduce the starting current. Current supply to the starter windings is connected in star (Y) coniguration or starting. Current supply is reconnected to the windings in delta (∆ ) coniguration once the the motor has gained speed.
Sot starter A sot starter is a device which ensures a sot start o a motor. This is done by raising the voltage within a preset voltage rise time.
Frequency converter starting Frequency converters are designed or continuous eeding o motors, but they can also be used or sot starting.
1.4.3 Voltage supply The motor’s rated voltage lies within a certain voltage range. Figure 1.4.12 shows typical voltage range examples or 60 Hz motors. According to the NEMA standard, the motor has to be able to operate with a main voltage tolerance o ± 10% rom the lowest and highest voltage in the range.
1.4.4 Frequency conv converter erter Frequency converters are oten used or speed controlled pumps, see chapter 4. The requency converter converts the main voltage into a dierent voltage and requency, causing the motor to run at a dierent speed. This way o regulating r egulating the requency might result in some problems:
• Acoustic noise rom the motor which is sometimes transmitted to the system as noise
• High voltage peaks on the output rom the requency converter to the motor
Typical North America voltage examples 60 Hz 60 Hz motors come with the ollowing voltages: • 1 x 115 – 230 ∆ / 346 – 400 Y • 1 x 115/208-230 • 1 x 208-230 • 1 x 230 • 3 x 208-230/460 • 3 x 230/460 • 3 x 575 Fig 1.4.12: Typical voltages
Section 1.4 Motors
Insulation or motors with requency converters
Phase insulation also reerred to as phase paper
The discussion below highlights dierent kinds o motors with requency converters and how dierent kinds o insulation aect the motor.
Motors without phase insulation For motors constructed without phase insulation, continuous voltages known as Root Mean Square voltages (RMS) above 460 V can increase the risk o disruptive discharges in the windings and destroy the motor. This applies to all motors constructed according to these principles. Continuous operation with voltage peaks above 650 V can cause damage to the motor.
Motors with phase insulation Phase insulation is normally used in three-phase motors. Speciic precautions are not necessary i the voltage supply is less than 500 V.
Motors with reinorced insulation With supply voltages between 500 V and 690 V, the motor has to have reinorced insulation or be protected with delta U /delta T ilters. For supply voltages o 690 V and higher, the motor has to be itted with both reinorced insulation and delta U /delta T ilters.
Motors with insulated bearings In order to avoid harmul current lows through the bearings, the motor bearings have to be electrically insulated. This generally applies to motors >- 40 hp run with variable requency drives. Motor manuacturers will use special ceramic coatings to insulate one or both bearings.
Fig 1.4.13: Stator with phase insulation
Motor eiciency In general, electric motors are quite eicient. Some have electricity-to-shat power eiciencies o 8093% depending on the motor size and sometimes even higher or bigger motors. There are two types o energy losses in electric motors: Load-dependent and load-independent losses. Load-dependent losses vary with the square o the current and cover:
• Stator winding losses (copper losses) • Rotor losses (slip losses) • Stray losses (in dierent parts o the motor) Load-independent losses in the motor reer to:
• Iron losses (core losses) • Mechanical losses (riction) Motors are categorized according to eiciency. The most important classiications are Environmental Protection Act in the US (EPact) and CEMEP in the European Union (EFF1, EFF2 and EFF3). 1
100
0.8
80
0.6 s o C
0.4 0.2
Motors can ail due to overload or long periods o time so are oten intentionally oversized and operate at 75% to 80% o their ull load capacity. At this level o loading, motor eiciency and power remain relatively high, but when motor load is less than 25%, eiciency and power decrease. Motor eiciency drops quickly below a certain percentage o rated load. Thereore, it is important to size the motor so that losses associated with running the motor too ar below its rated capacity are minimized. It is common to choose a motor that meets the power requirements o the pump.
1.4.5 Motor protection Motors are usually protected against high temperatures that can damage the insulation system. Depending on motor construction and application, thermal protection can also prevent damaging temperatures in the requency converter i it is mounted on the motor. Thermal protection varies with motor type. Motor construction and its power consumption must be considered when choosing thermal protection. Generally, motors must be protected against the ollowing:
60
t n e c r e P
40 20
Fig 1.4.14: Eiciency vs. load and power vs. load (schematic drawing)
Efficiency Power factor 0
25
50 75 100 125 Per cent of rated load
150
100
100 hp
90
10 hp 80
1 hp
70
%60 y c n 50 e i c i f f E 40
Fig 1.4.15: The relationship between eiciency and rated load o dierent sized motors (schematic drawing)
30 20 10 0 0
25
50
75
100
125
Percent of rated load
150
175
Errors causing slow temperature increase in the windings: • Slow overload • Long start-up periods • Reduced cooling / lack o cooling • Increased ambient temperature • Frequent starts and stops • Frequency luctuation • Voltage luctuation Errors causing ast temperature increase in the windings: • Blocked rotor • Phase ailure
Thermal protection A motor’s thermal protection (TP) is provided by a temperature-sensing device that is built in to the motor. When motor temperature becomes excessively hot due to ailure-to-start or overloading, the sensor device shuts o the motor. This is especially important or motors that start automatically, are unattended, or or motors that are located remotely or operated o-sight. The basic types o temperature sensing devices include: • Automatic Reset - The thermal protector automatically restores power ater the motor cools. Note: This should not be used where unexpected restarting would be hazardous.
• Manual Reset - Power to the motor is restored by pushing an external button. This type is preerred where unexpected restarts would be hazardous.
• Impedance Protected - The motor is designed to protect itsel under locked rotor (stalled) conditions, in accordance with UL standards.
TP 111 TP 112 TP 121 TP 122 TP 211 TP 212 TP 221 TP 222 TP 311 TP 312
Technical overload with variation (1 digit) Only slow (i.e. constant overload) Slow and ast (i.e. constant overload and blocked condition )
Only ast PTC thermistors (i.e. blocked condition)
Number of levels and function area (2 digits)
Category 1 (3 digits)
1 level at cuto
1 2 1 2 1 2 1 2 1 2
2 levels at emergency signal and cuto 1 level at cuto 2 levels at emergency signal and cuto 1 level at cuto
Indication o the permissible temperature level when the motor is exposed to thermal overload. Category 2 allows higher temperatures than category 1 does.
Fig 1.4.16: TP designations
Thermal switch and thermostats Thermal switches are small bi-metallic switches that change state due to the temperature. They are available with a wide range o trip temperatures; normally open and closed types, with closed being the most common. One or two, in series, are usually ftted in the windings like thermistors and can be connected directly to the circuit o the main contactor coil, requiring no relay. This type o protection is less expensive than thermistors; however, it is less sensitive and is not able to detect a locked rotor ailure. Thermal switches are also reerred to as Klixon thermal switches and Protection thermal overload (PTO). Thermal switches always carry a TP111 designation.
Single-phase motors
According to the IEC 60034-11 standard, the thermal protection (TP) o the motor has to be indicated on the nameplate with a TP designation. Figure 1.4.16 shows an overview o the TP designations.
Symbol
Positive Temperature Coeicient (PTC thermistors) can be itted into the windings o a motor during production or aterwards. Usually three PTCs are itted in series; one in each phase o the winding.They can be purchased with trip temperatures ranging rom 194°F to 356°F. PTCs have to be connected to a thermistor relay which detects the rapid increase in resistance o the thermistor when it reaches its trip temperature.
Single-phase motors normally come with thermal protection. Thermal protection usually has an automatic reclosing. This implies that the motor has to be connected to the main voltage supply in a way to ensure that accidents caused by the automatic reclosing are avoided.
Three-phase motors Three-phase motors have to be protected according to local regulations. This kind o motor usually has contacts or resetting in the external control circuit.
Space Heater
The ixed bearing in the drive end can be a deep-groove ball bearing or an angular contact bearing.
A heating element ensures the standby heating o the motor and is used with applications that struggle with humidity and condensation. By using the space heater, the motor is warmer than the surroundings, and thereby, the relative air humidity inside the motor is always lower than 100%.
Bearing clearances and tolerances are stated according to ISO 15 and ISO 492. Because bearing manuacturers must ulill these standards, bearings are internationally interchangeable. In order to rotate reely, a ball bearing must have a certain internal clearance between the raceway and the balls. Without this internal clearance, the bearings can be diicult to rotate or they may seize up and be unable to rotate. Conversely, too much internal clearance will result in an unstable bearing that may generate excessive noise or allow the shat to wobble.
Fig 1.4.17: Space heater
Depending on the pump type to which the motor is itted, the deep-groove ball bearing in the drive end must have C3 or C4 clearance. Bearings with C4 clearance are less heat sensitive and have increased axial load-carrying capacity. The bearing carrying the axial orces o the pump can have C3 clearance i:
Maintenance The motor should be checked at regular intervals. It is important to keep the motor clean to ensure adequate ventilation. I the pump is installed in a dusty environment, the pump must be cleaned and checked regularly.
• The pump has complete or partial partial hydraulic hydraulic relie • The pump has many brie periods periods o operation operation • The pump has long long idle periods periods C4 bearings are used or pumps with luctuating high axial orces. Angular contact bearings are used i the pump exerts strong one-way axial orces.
Non-drive end
Drive end
Bearings There are several types o bearing designs. Normally, motors have a locked bearing in the drive end and a bearing with axial play in the non-drive end. Axial play is required due to production tolerances, thermal expansion during operation, and other actors. The motor bearings are held in place by wave spring washers in the non-drive end, see igure 1.4.18.
Spring washer
Non-drive end bearing
Fig 1.4.18: Cross-sectional drawing o motor
Drive end bearing
Section 1.4 Motors
Axial orces
Bearing types and recommended clearance Drive end
Non-drive end
Moderate to strong orces. Primarily outward pull on the shat end
Fixed deep-groove ball bearing (C4)
Deep-groove ball bearing (C3)
Strong outward pull on the shat end
Fixed angular contact bearing
Deep-groove ball bearing (C3)
Fixed deep-groove ball bearing (C3)
Deep-groove ball bearing (C3)
Small orces (lexible coupling)
Fixed deep-groove ball bearing (C3)
Deep-groove ball bearing (C3)
Strong inward pressure
Deep-groove ball bearing (C4)
Fixed angular contact bearing
Moderate orces. Primarily outward pull on the shat end (partly hydraulically relieved in the pump)
Fig:1.4.19: Typical Typical types o bearings in pump motors
Motors with permanently lubricated bearings For closed permanently lubricated bearings, one o the ollowing high temperature resistant types o grease are normally used: • Lithium-based grease • Polyurea-based grease
The grease zerks are visible and are easily accessible. The motor is designed so that: • there is a fow o grease around the bearing • new grease enters the bearing • old grease is removed rom the bearing
Motors with lubrication system
Motors with lubricating systems are normally labeled on the an cover and are supplied with a lubricating instruction. Apart rom that, instructions are given in the installation and operating instructions.
Many integral size motors have lubricating nipples or the bearings both in the drive end and the nondrive end. This may vary by b y manuacturer.
The lubricant is oten a lithium-based, high temperature grease. The basic oil viscosity must be: • Higher than 50 cSt at 104°F • 8 cSt at 212°F
Chapter 1. Design o pumps and motors
Section 1.5: Liquids 1.5.1 Viscous liquids 1.5.2 Non-Newtonian liquids 1.5.3 The impact o viscous liquids on the perormance o a centriugal pump 1.5.4 Selecting the the right pump or a liquid with antireeze 1.5.5 Calculation example 1.5.6 Computer-aided pump selection or dense and viscous liquids
Section 1.5 Liquids
1.5.1 Viscous liquids While water is the most common liquid that pumps handle, in a number o applications, pumps have to handle other types o liquids, e.g. oil, propylene glycol, gasoline. Compared to water, these types o liquids have dierent densities and viscosities. Viscosity is a measure o the resistance o a substance to low. The higher the viscosity, the more diicult the liquid will low on its own. Propylene glycol and motor oil are examples o thick or high viscous liquids. Gasoline and water are examples o thin, low viscous liquids. Two kinds o viscosities exist: • The dynamic viscosity (μ), which is normally measured in Poise (1 Poise)
μ ρ
ν=
• The kinematic viscosity ( ν), which is normally measured
ρ = density o liquid
in centiStokes (cSt) The relationship between the dynamic viscosity ( μ) and the kinematic viscosity (ν) is shown in the ormula at right. On the ollowing pages, we will ocus on kinematic viscosity (ν). The viscosity o a liquid changes considerably with the change in temperature; hot oil is thinner than cold oil. As you can tell rom igure 1.5.1, a 50% propylene glycol liquid increases its viscosity 10 times when the temperature changes rom +68 to –4 oF. For more inormation concerning liquid viscosity, go to Appendix K.
Liquid
Water Gasoline Olive oil 50% Propylene glycol 50% Propylene glycol
Liquid Density temperature ρ[lb/ft3] t [°f] 68 68 68 68 -4
62.4 45.75 56.18 65.11 66.23
Kinematic viscosity ν [cSt] 1.004 0.75 93 6.4 68.7
Fig. 1.5.1: Comparison o viscosity values or water and a ew other liquids. Density values and temperatures are also shown
1.5.2 Non-Newtonian liquids The liquids discussed so ar are reerred to as Newtonian luids. The viscosity o Newtonian liquids is not aected by the magnitude and the motion that they are exposed to. Mineral oil and water are typical examples o this type o liquid. On the other hand, the viscosity o non-Newtonian liquids does change when agitated. A ew examples o non-Newtonion liquids include: • Dilatant liquids, like cream, exhibit a viscosity increase when agitated • Plastic luids, like ketchup, have a yield value which
must be exceeded beore the low starts. From that point on, the viscosity decreases with an increase in agitation • Thixotropic liquids, like non-drip paint, exhibit a
reezing. When glycol or a similar antireeze agent
is added to the pumped liquid, the liquid obtains properties dierent rom those o water. The liquid will have a: • Lower reezing point, t [°F] • Lower speciic heat, c p [btu/lbm °F] • Lower thermal conductivity, λ[btu t/h t2 °F] • Higher boiling point, t b [°F] • Higher coeicient o expansion, β[t/°F] • Higher density, ρ[lb/t3] • Higher kinematic viscosity, ν [cSt]
These properties must be considered when designing a system and selecting pumps. As mentioned, the higher density requires increased motor power and the higher viscosity reduces pump head, low rate and eiciency resulting in a need or increased motor power, see igure 1.5.2.
H, P, η
P
decrease in viscosity with an increase in agitation The non-Newtonian liquids are not covered by the viscosity ormula described earlier in this section.
H
1.5.3 The impact o viscous liquids on the perormance o a centriugal pump Liquid with higher viscosity and/or higher density than water aects the perormance o centriugal pumps in dierent ways: • Power consumption increases, i.e. a larger motor
may be required to perorm the same task • Head, low rate and pump eiciency are reduced
For example, when a pump is used or pumping a liquid in a cooling system with a liquid temperature below 32oF, an antireeze agent like propylene glycol is added to the water to prevent the liquid rom
η
Q
Fig. 1.5.2: Changed head, eiciency and power input or liquid with higher viscosity
Section 1.5 Liquids
1.5.4 Selecting the right pump or a liquid with antireeze Pump characteristics are usually based on water temperature at around 68°F, i.e. a kinematic viscosity o approximately 1 cSt and is 1.0 speciic gravity. When pumps are used or liquids containing antireeze below 32°F, it is necessary to determine, most importantly, that the pump can meet the required perormance or i a larger motor is required. The ollowing section presents a simpliied method used to determine pump curve corrections or pumps in systems that must handle liquids with a viscosity between 5 cSt - 100 cSt and (speciic gravity o 1.0). Please notice that this method is not as precise as the computer-aided method described later in this section.
Pump curve corrections or pumps handling h andling high viscous liquid Based on knowledge about required duty point, low (QS,), head (HS,) and kinematic viscosity o the pumped liquid, the correction actors o H and P 2 can be ound, see igure 1.5.3. To get the correction actor or multistage pumps, the head o one stage has to be used.
Fig. 1.5.3: It is possible to determine the correction actor or head and power consumption at dierent low, head and viscosity values
Figure 1.5.3 is read in the ollowing way:
H
When kH and kP2 are ound in the igure, the equivalent head or clean water H W and the corrected actual shat power P2S can be calculated by the ollowing ormula
H =k .H w
H
Hw
Water
2 S
Hs
1
HW = kH . HS P2S = kP2 . P2w .
Mixture
(..) ρs ρw
Qs
Q
3
P
where HW : is the equivalent equivalent head o the pump i the pumped liquid is “clean” water P2W : is the shat power at the duty point (Q S,HW) when the pumped liquid is water HS : is the desired head o the pumped liquid with agents
P2s P
2S
=K
P2
.P
2w
.
( ) ρs ρw
P2w
5
4
Mixture
Water
Q
Fig. 1.5.4: Pump curve correction when choosing the right pump or the system
P2S : is the shat power at the the duty point (Q s,Hs) or the viscous pumped liquid water (with agents)
The pump and motor selection procedure contains the ollowing steps:
ρs :
• Calculate the corrected head H w (based on Hs and kH ), see igure 1.5.4 lines 1 and 2
is the the speciic gravity o the the pumped liquid
ρw : is the speciic gravity o water water = 1.0
The pump selection is based on the normal data sheets/curves applying to water. The pump should cover the duty point low and head, and the motor should be powerul enough to handle the power input on the shat. Figure 1.5.4 shows how to proceed when selecting a pump and testing whether the motor is within the power range allowed.
• Choose a pump capable o providing perormance according to the corrected duty point (Q s, Hw) • Read the the power input input P2w at the duty point (Q s,Hw), see igure 1.5.4 lines 3 and 4 • Based on P2w, kp2, ρw, and ρs calculate the corrected required shat power P2s, see igure 1.5.4, lines 4 and 5 • Check i P2s is less than P2 max o the motor. I that is the case, the motor can be used. Otherwise select a more powerul motor • Ensure NPSHr < NPSHa
Section 1.5 Liquids
1.5.5 Calculation example A circulator pump in a rerigeration system is to pump a 40% (weight) propylene glycol liquid at 14°F. The desired low is QS = 260 GPM, and the desired head is HS = 40 t. I the required duty point is known, it is possible to ind the QH-characteristic or water and choose a pump to cover the duty point. Once the pump type and size is determined, the pump is itted with a motor which can handle the speciic pump load. The liquid has a kinematic viscosity o 20 cSt and a speciic gravity o 65.48 lb/t3. With QS = 260 GPM, HS = 40 t and ν = 20 cSt, the correction actors can be ound in igure 1.5.3.
1.5.6 Computer-aided pump selection or dense and viscous liquids Some computer-aided pump selection tools include a eature that compensates or the pump perormance curves based on input o the liquid density and viscosity. Figure 1.5.5 shows the pump perormance curves rom the example at let. The gure shows both the perormance curves or the pump when it handles viscous liquid (the ull lines) and the perormance curves when it handles water (the broken lines). As indicated, head, fow and eciency are reduced resulting in an increase in power consumption. The value o P2 is 4.5 hp which corresponds to the result as shown in the calculation example in section 1.5.4.
kH = 1.03 kP2 = 1.15 HW = kH · HS = 1.03 · 12 = 40 t
η
H
[ft]
QS = 260 GPM
[%]
60 50
The pump selection has to cover a duty point equivalent to Q,H = 260 GPM, 40 t. Once the necessary pump size is selected, the P2 value or the duty point is determined, which in this case is P 2W = 3.8 hp. It is now possible to calculate the required motor power or the propylene glycol mixture:
40
20
70 60 50 40
10
20
30
30 10 0 0 P2 [hp]
50
100
150
200
250
300
350
400
Q [GPM] 0 NPSH (ft)
6 4
P2S = kP2 . P2w .
ρS ρw
2 0 Q [GPM]
Fig. 1.5.5: Pump perormance curves
1049 P2S = 1.15 . 3.8 . 998
= 4.6 hp
The calculation shows that the pump has to be itted with a 5 hp motor, which is the smallest motor size able to cover the calculated P 2S = 4.6 hp.
Chapter 1. Design o pumps and motors
Section 1.6: Materials 1.6.1 1.6.2 1.6.3 1.6.4 1.6.5 1.6.6 1.6.7
What is corrosion? Types o corrosion Metal and and metal metal alloys Ceramics Plastics Rubber Coatings
Section 1.6 Materials
This section discusses the dierent materials used or pump construction, including the eatures that every single metal and metal alloy have to oer. Corrosion will be deined, and and the dierent types types will be identiied, as well as what can be done to prevent corrosion rom occurring.
1.6.1 What is corrosion? Corrosion is usually reerred to as the degradation o the metal by chemical or electrochemical reaction with its environment, see igure 1.6.1. Considered broadly, corrosion may be looked upon as the tendency o the metal to revert to its natural state similar to the oxide rom which it was originally melted. Only precious metals, such as gold and platinum, are ound in nature in their metallic state. Some metals produce a tight protective oxide layer on the surace which hinders urther corrosion. I the surace layer is broken, it is sel-healing. These metals are passivated. Under atmospheric conditions, the corrosion products o zinc and aluminum orm a airly tight oxide layer and urther corrosion is prevented. Likewise, on the surace o stainless steel, a tight layer o iron and chromium oxide is ormed, and on the surace o titanium, a layer o titanium oxide is ormed. The protective layers o these metals demonstrate their good corrosion resistance. Rust, on the other hand, is a non-protective corrosion product on steel. Rust is porous, not irmly adherent and does not prevent continued corrosion, see igure 1.6.2.
Environmental variables that affect the Environmental corrosion resistance of metals and alloys pH (acidity) Oxidizing agents (such as oxygen) Temperature Concentration of solution constituents (such as chlorides) Biological activity Operating conditions (such as velocity, cleaning procedures and shutdowns)
Fig. 1.6.1: Environmental variables variables that aect the corrosion resistance o metals and alloys
Rust on steel
Non-protective corrosion product Oxide layer on stainless steel
Protective corrosion product Fig. 1.6.2: Examples o corrosion products
1.6.2 Types o corrosion Generally, metallic corrosion involves the loss o metal at a spot on an exposed surace. Corrosion occurs in various orms ranging rom uniorm attacks over the entire surace to severe local attacks. The environment’s chemical and physical conditions determine both the type and the rate o corrosion attacks. The conditions also determine the type o corrosion products that are ormed and the control measures that must be taken. In many cases, it is impossible or rather expensive to completely stop the corrosion process; however, it is usually possible to control the severity to acceptable levels. On the ollowing pages, dierent orms o corrosion and their characteristics will be discussed.
Uniorm corrosion Uniorm or general corrosion is characterized by corrosive attacks spreading evenly over the entire surace or on a large part o the total area. General thinning continues until the metal is broken down. Uniorm corrosion results in waste o most o the metal.
Fig. 1.6.3: Uniorm corrosion
Examples o metals subject to uniorm corrosion include: • Steel in aerated aerated water • Stainless steel in reducing acids [such as AISI 304 (EN 1.4301) in suluric acid]
Pitting corrosion Pitting corrosion is a localized orm o a corrosive attack. Pitting corrosion orms holes or pits on the metal surace. It perorates the metal while the total corrosion, measured by weight loss, might be rather minimal. The rate o penetration penetration may be 10 to 100 times that o general corrosion depending on the aggressiveness o the medium. Pitting occurs more oten in a stagnant environment. An example o metal subject to pitting corrosion: • Stainless steel in seawater
Fig. 1.6.4: Pitting corrosion
1. Design Sectiono 1.6pumps and motors Materials 1.1 Pump construction, (10)
Crevice corrosion Crevice corrosion, like pitting corrosion, is a localized orm o corrosion attack. However, crevice corrosion is more aggressive. Crevice corrosion occurs at narrow openings or spaces between two metal suraces or between metals and non-metal suraces and is usually associated with a stagnant condition in the crevice. Crevices, such as those ound at lange joints or at threaded connections, are oten the most critical spots or corrosion.
Fig. 1.6.5: Crevice corrosion
An example o metal subject to crevice corrosion: • Stainless steel in seawater
Intergranular corrosio corrosion n Intergranular corrosion occurs at grain boundaries. Intergranular corrosion, also called intercrystalline corrosion, typically occurs when chromium carbide precipitates at the grain boundaries during the welding process or in connection with insuicient heat treatment. A narrow region around the grain boundary may become deplete in chromium and become less resistant to corrosion than the rest o the material. This is unortunate because chromium plays an important role in corrosion resistance.
Fig. 1.6.6: Intergranular corrosion
Examples o metals subject to intergranular corrosion include: • Insuiciently welded or heat-treated stainless steel steel • Stainless steel AISI 316 (EN 1.4401) in nitric acid
Selective corrosion
Brass
Selective corrosion attacks one single element o an alloy and dissolves the element in the alloy structure. Consequently, the alloy’s structure is weakened. Examples o selective corrosion: • The dezinciication o unstabilized brass producing a weakened, porous copper structure • Graphitization o gray cast iron leaving a brittle graphite skeleton due to the dissolution o iron.
Zinc corrosion products Copper
Fig. 1.6.7: Selective corrosion
Erosion corrosion Erosion corrosion is a process whereby the rate o corrosion attack is accelerated by the relative motion o a corrosive liquid and a metal surace. The attack is localized in areas with high velocity or turbulent low. Erosion corrosion attacks are characterized by grooves with a directional pattern.
Examples o metals subject to erosion corrosion: • Bronze in seawater • Copper in water
Flow
Fig. 1.6.8: Erosion corrosion
Cavitation corrosion Cavitation corrosion occurs when a pumped liquid with high velocity reduces the pressure, and it drops below the liquid vapor pressure orming vapor bubbles. In the areas where the vapor bubbles orm, the liquid boils. When the pressure rises again, the vapor bubbles collapse and produce intensive shockwaves. Consequently, the collapse o the vapor bubbles remove metal or oxide rom the surace. Examples o metals that are subject to cavitation: • Cast iron in water at at high temperature temperature • Bronze in seawater
Fig. 1.6.9: Cavitation corrosion
Stress corrosion cracking Stress corrosion cracking (SCC) reers to the combined inluence o tensile stress (applied or internal) and corrosive environment. The material can crack without any signiicant deormation or obvious deterioration o the material. Oten, pitting corrosion is associated with SCC. Examples o metals that are subject to SCC: • Stainless steel AISI 316 (EN 1.4401) 1.4401) in chlorides • Brass in ammonia
Fig. 1.6.10: Stress corrosion cracking
1. Design Sectiono 1.6pumps and motors Materials 1.1 Pump construction, (10)
Corrosion atigue < Pure mechanical atigue occurs when a material subjected to a cyclic load ar below the ultimate tensile strength ails. I the metal is simultaneously exposed to a corrosive environment, the ailure can take place at an even lower stress and ater a shorter period o time. Contrary to a pure mechanical atigue, there is no atigue limit in corro sion-assisted atigue.
Fig. 1.6.11: Corrosion atigue
An example o a metal subject to corrosion atigue: • Aluminium structures in a corrosive atmosphere
Galvanic corrosion Galvanic corrosion occurs when a corrosive electrolyte and two metallic materials are in contact (galvanic cell) and corrosion increases on the least noble material (the anode) and decreases on the noblest material (the cathode). The tendency o a metal or an alloy to corrode in a galvanic cell is determined by its position in the galvanic series. The galvanic series indicates the relative nobility o dierent metals and alloys in a given environment (e.g. seawater, see igure 1.6.13).The arther apart the metals are in the galvanic series, the greater the galvanic corrosion eect will be. Metals or alloys at the upper end are more noble than those at the lower end.
A lum iniumGalvanic - less nocorrosion ble Fig. 1.6.12:
Copper - most noble
Examples o metals that are subject to galvanic corrosion include: • Steel in contact with with AISI 316 (EN 1.4401) • Aluminum in contact with copper The principles o galvanic corrosion are used in cathodic protection. Cathodic protection is the reduction or prevention o the corrosion o a metal surace through the use o sacriicial anodes (zinc or aluminum) or impressed currents. Fig. 1.6.13: Galvanic series or metals and alloys in seawater
1.6.3 Metal and metal alloys On the ollowing pages, the eatures o dierent metals and metal alloys used or construction o pumps are discussed.
Ferrous alloys
Cavitation corrosion o bronze impeller
Ferrous alloys are alloys where iron is the prime constituent. Ferrous alloys are the most common o all materials because o their availability, low cost, and versatility.
Steel Steel is a widely used material primarily composed o iron alloyed with carbon. The amount o carbon in steel varies in the range rom 0.003% to 1.5% by weight. The content o carbon has an important impact on the material’s strength, weldability, machinability, ductility, and hardness. Generally, an increase in carbon content will lead to an increase in strength and hardness but to a decrease in ductility and weldability. The most common type o steel is carbon steel. Carbon steel is grouped into our categories, see igure 1.6.14.
Erosion corrosion o cast iron impeller
Pitting corrosion o AISI 316 (EN 1.4401)
Steel is available in wrought and cast grades. Cast steel is closely comparable to wrought; both are relatively inexpensive to make, orm, and process but have low corrosion resistance compared to alternative materials such as stainless steel. 0.0394 inch
Intergranular corrosion o stainless steel
Crevice corrosion o SAF 2205 (EN 1.4462)
Type of steel
Content of carbon
Low carbon or mild steel
0.003% to 0.30% of carbon
Medium carbon steel
0.30% to 0.45% of carbon
High carbon steel
0.45% to 0.75% of carbon
Very high carbon steel
0.75% to 1.50% of carbon
Fig 1.6.14: Four types o carbon steel
1. Design Sectiono 1.6pumps and motors Materials 1.1 Pump construction, (10)
Cast iron
Nodular (ductile) iron
Cast iron is an alloy o iron, silicon and carbon. Typically, the concentration o carbon is between 3-4% by weight, most o which is present in insoluble orm (e.g. graphite lakes or nodules). The two main types are grey cast iron and nodular (ductile) cast iron. The corrosion resistance o cast iron is comparable to that o steel; and a nd sometimes even better. Cast iron can be alloyed with 13-16% (by weight) silicon or 15-35% (by weight) nickel (Ni-resist) to improve corrosion resistance. Various types o cast irons are widely used in industry, especially or valves, pumps, pipes and automotive parts. Cast iron has good corrosion resistance to neutral and alkaline liquids (high pH) but has poor resistance to acids (low pH).
Nodular iron contains around 0.03-0.05% (by weight) o magnesium. Magnesium causes the lakes to become globular, so the graphite is dispersed throughout a errite or pearlite matrix in the orm o spheres or nodules. The round shape o nodular graphite reduces the stress concentration and consequently, the material is much more ductile than grey iron. Figure 1.6.16 shows that the tensile strength is higher or nodular iron than or grey iron. Nodular iron is normally used or pump parts with high strength requirements (high pressure or high temperature applications).
Stainless steel Grey iron In grey iron, the graphite is dispersed throughout a errite or pearlite matrix in the orm o lakes. Fracture suraces take on a grey appearance (hence the name). The graphite lakes act as stress concentrators under tensile loads making the material weak and brittle in tension, but strong and ductile in compression. Grey iron is used or the construction o motor blocks because o its high vibration damping ability. Grey iron is an inexpensive material and is relatively easy to cast with a minimal risk o shrinkage. That is why grey iron is oten used or pump parts with moderate strength requirements.
Stainless steel is composed o chromium containing steel alloys. The minimum chromium content in standardized stainless steel is 10.5%. Chromium improves the corrosion resistance o stainless steel. This is due to a chromium oxide ilm that is ormed on the metal surace. This extremely thin layer is sel-repairing under the right conditions. Molybdenum, nickel and nitrogen are other examples o typical alloying elements. Alloying with these elements brings out dierent crystal structures which enable dierent properties in connection with machining, orming, welding and corrosion resistance. In general, stainless steel has a higher resistance to chemicals (i.e. acids) than steel and cast iron.
0
ASTM
150
EN-GJL-150
GG-15
50
-
-
-
EN-GJL-200
GG-20
200
-
-
-
-
A 48 Gr 30A
-
-
-
A 48 Gr 35A
EN-GJL-250
GG-25
250
-
172
200 207
400
EN-GJS-400-18
GGG-40
400-18
-
400
EN-GJS-400-15
GGG-40.3
400-15
-
430
-
-
-
450
EN-GJS-450-10
-
450-10
-
-
-
A 48 Gr 25A
460
241 250
Fig 1.6.15: Comparison and designations o grey iron
ASTM
500
EN-GJS-500-7
575
-
GGG-50
-
A 536 Gr 60-40-18
A 536 Gr 65-45-12
500-7
-
A 536 Gr 80-55-06
Fig 1.6.16: Comparison and designations o nodular iron
In environments containing chlorides, stainless steel can be attacked by localized corrosion, such as pitting corrosion and crevice corrosion. The resistance o stainless steel to these types o corrosion is highly dependent on its chemical composition. It is common to use the so-called Pitting Resistance Equivalent (PRE) values as a measure o pitting resistance or stainless steel. PRE values are calculated by ormulas where the relative inluence o a ew alloying elements (chromium, molybdenum and nitrogen) on the pitting
resistance is taken into consideration. The higher the PRE, the higher the resistance to localized corrosion. Be aware that the PRE value is a rough estimate o the pitting resistance o a stainless steel and should only be used or comparison/classiication o dierent types o stainless steel. To ollow, the our major types o stainless steel: erritic, martensitic, austenitic and duplex are presented.
Fig 1.6.17: Chemical composition o stainless steel
Chemical composition composition of stainless steel [w%] Microstructure
Designation EN/AISI/UNS
% Carbon max.
% Chromium
Ferritic
1.4016/430/ S43000
0.08
16-18
Martensitic
1.4057/431/ 1.4057/4 31/ S43100
0.12-0.22 0.12-0 .22
15-17
1.5-2.5
Austenitic
1.4305/303/ S30300
0.1
17-19
8-10
Austenitic
1.4301/304/ S30400
0.07
17-19.5
8-10.5
18
Austenitic
1.4306/304L/ S30403
0.03
18-20
10-12
18
Austenitic
1.4401/316/ S31600
0.07
16.5-18.5
10-13
2-2.5
24
Austenitic
1.4404/316L/ S31603
0.03
16.5-18.5
10-13
2-2.5
24
Austenitic
1.4571/316Ti/ S31635
0.08
16.5-18.5
10.5-13.5
2-2.5
Ti > 5 x carbon Ti < 0.70
24
Austenitic
1.4539/904L/ N08904
0.02 0.02
19-21
24-26
4-5
Cu 1.2-2
34
Austenitic
1.4547/none / 1.4547/none S 31254 3)
0.02
20
18
6.1
N 0.18-0 0.18-0.22 .22 Cu 0.5-1
43
Ferritic/ austenitic
1.4462/ none/ S32205 2)
0.03
21-23
4.5-6.5
2.5-3.5
N 0.10-0 0.10-0.22 .22
34
Ferritic/ austenitic
1.4410/none/ S 32750 4)
0.03
25
7
4
N 0.24-0 0.24-0.32 .32
43
Microstructure
Designation EN/ASTM/UNS
% Carbon max.
% Chromium
% Nickel
% Molybdenum
% Other
PRE
Austenitic 1)
1.4308/CF8/ J92600
0.07
18-20
8-11
Austenitic 1)
1.4408/CF8M/ J92900
0.07
18-20
9-12
2-2.5
Austenitic 1)
1.4409/CF3M/ J92800
0.03
18-20
9-12
2-2.5
N max. 0.2
26
Austenitic
1.4584/none/ none
0.025 0.025
19-21
24-26
4-5
N max. 0.2 Cu 1-3
35
Ferritic/ austenitic
1.4470/CD3MN/ J92205
0.03
21-23
4.5-6.5
2.5-3.5
N 0.12-0.2
35
Ferritic/ austenitic
1.4517/CD4MCuN/ J93372
0.03
24.5-26.5
2.5-3.5
2.5-3.5
N 0.12-0.22 Cu 2.75-3.5
38
Contains some errite 2) Also known as SAF 2205, 3) Also known as 254 SMO, 5) Pitting Resistance Equivalent (PRE): Cr% + 3.3xMo% + 16xN%. 1)
% Nickel
% Molybdenum
% Other
PRE 5) 17
4)
16 S 0.15-0 0.15-0.35 .35
18
19
Also known as SAF 2507
26
1. Design Sectiono 1.6pumps and motors Materials 1.1 Pump construction, (10)
Ferritic (magnetic) Ferritic stainless steel is characterized by good corrosion properties, resistance to stress corrosion cracking, and moderate toughness. Low alloyed erritic stainless steel is used in mild environments (teaspoons, kitchen sinks, washing machine drums, etc.) where maintenance-ree and non-rusting is required.
I low carbon grades o stainless steel are used, the risk o sensitization is reduced. Stainless steel with a low content o carbon is reerred to as AISI 316L (EN 1.4306), or AISI 304L (EN 1.4404). Both grades contain 0.03% o carbon compared to 0.07% in the regular type o stainless steel, AISI 304 (EN 1.4301) and AISI 316 (EN 1.4401), see illustration 1.6.17.
Martensitic stainless steel is characterized by high strength and limited corrosion resistance. Martensitic steels are used or springs, shats, surgical instruments and or sharp-edged tools, such as knives and scissors.
The stabilized grade AISI 316Ti (EN 1.4571) contains a small amount o titanium. Because titanium has a higher ainity or carbon than chromium, the ormation o chromium carbides is minimized. The content o carbon is generally low in modern stainless steel, and with the easy availability o ‘L’ grades, the use o stabilized grades has declined signiicantly.
Austenitic (non-magnetic)
Ferritic-austenitic or duplex (magnetic)
Austenitic stainless steel is the most common type o stainless steel and is characterized by a high corrosion resistance, good ormability, toughness and weldability. Austenitic stainless steel, especially the AISI 304 and AISI 316, are used or almost any type o pump components. This kind o stainless steel can be either wrought or cast.
Ferritic-austenitic (duplex) stainless steel is characterized by strength, toughness, high corrosion resistance and excellent resistance to stress corrosion cracking and corrosion atigue. Ferritic-austenitic stainless steel is typically used in applications that require high strength, high corrosion resistance and low susceptibility to stress corrosion cracking or a combination o these properties. Stainless steel SAF 2205 is widely used or making pump shats and pump housings.
Martensitic (magnetic)
AISI 303 is one o the most popular stainless steel types o all the ree machining stainless steel types. Due to its high sulphur content (0.15-0.35 w%), the machinability improves considerably but corrosion resistance and weldability decrease. Over the years, ree machining grades with a low sulphur content and a higher corrosion resistance have been developed. I stainless steel is heated up to 932°F - 1472°F or a relatively long period o time during welding, the chromium may orm chromium carbides with the carbon in the steel. This reduces chromium’s capability to maintain the passive ilm and may lead to intergranular corrosion, also reerred to as sensitization sensitizati on (see section 1.6.2).
Nickel alloys
Copper alloys
Nickel based alloys are deined as alloys in which nickel is present in greater proportion than any other alloying element. The most important alloying constituents are iron, chromium, copper, and molybdenum. The alloying constituents make it possible to orm a wide range o alloy classes. Nickel and nickel alloys have the ability to withstand a wide variety o severe operating conditions, including corrosive environments, high temperatures, high stresses or a combination o these actors.
Pure copper has excellent thermal and electrical properties but is a very sot and ductile material. Alloying additions result in dierent cast and wrought materials suitable or use in the production o pumps, pipelines, ittings, pressure vessels and or many marine, electrical and general engineering applications.
HastelloyTM alloys are commercial alloys containing nickel, molybdenum, chromium, and iron. Nickel based alloys - such as InconelTM Alloy 625, HastelloyTM C-276 and C-22 - are corrosion resistant, not subject to pitting or crevice corrosion in low velocity seawater and do not suer rom erosion at high velocity. The price o nickel based alloy limits its use in certain applications. Nickel alloys are available in both wrought and cast grades. However, nickel alloys are more diicult to cast than the common carbon steels and stainless steel alloys. Nickel alloys are oten used or pump parts in the chemical process industry.
1) Lead can be added as an alloying element to improve machinability. 2) Bronze can be alloyed with aluminium to increase strength. Fig 1.6.18: Common types o copper alloys
Brasses are the most widely used o the copper alloys because o their low cost and easy or inexpensive abrication and machining. However, they are i nerior in strength to bronzes and must not be used in environments that cause dezinciication. Red brass, bronze and copper nickels, compared to cast iron, have a high resistance to chlorides in aggressive liquids, such as seawater. In such environments, brass is unsuitable because o its tendency to desinciicate. All copper alloys have poor resistance to alkaline liquids (high pH), ammonia, and sulides and are sensitive to erosion. Brass, red brass and bronze are widely used or making making bearings, impellers and pump housings.
1. Design Sectiono 1.6pumps and motors Materials 1.1 Pump construction, (10)
Aluminum
Titanium
Pure aluminum is a light and sot metal with a density o about a third o that o steel. Pure aluminum has a high electrical and thermal conductivity. The most common alloying elements are silicon (silumin), magnesium, iron and copper. Silicon increases the material’s castability, copper increases its machinability, and magnesium increases its corrosion resistance and strength.
Pure titanium has a low density, is quite ductile and has a relatively low strength. When a limited amount o oxygen is added, it will strengthen titanium and produce commercial-pure grades. Additions o various alloying elements, such as aluminum and vanadium, increase its strength signiicantly but at the expense o ductility. The aluminum and vanadium-alloyed titanium (Ti-6Al-4V) is the “workhorse” alloy o the titanium industry. It is used in many aerospace engine and airrame components. Because titanium is a high-price material, it is seldom used or making pump components.
An advantage o aluminum is its ability to generate a protective oxide ilm that is highly corrosion resistant i it is exposed to the atmosphere. Treatment, such as anodizing, can urther improve this property. Aluminum alloys are widely used in structures where a high strength to weight ratio is important, such as in the transportation industry. The use o aluminum in vehicles and aircrats reduces weight and energy consumption. A disadvantage o aluminum is its instability at low or high pH or in chloride-containing environments. This property makes aluminum unsuitable or exposure to aqueous solutions, especially under conditions with high low.
Titanium is a reactive material. Like stainless steel, titanium’s corrosion resistance depends on the ormation o an oxide ilm. Titanium’s oxide ilm is more protective than stainless steel’s. Thereore, titanium perorms much better than stainless steel in aggressive liquids, such as seawater, wet chlorine or organic chlorides, where pitting and crevice corrosion can occur.
This is urther emphasized by the act that aluminum is a reactive metal, i.e. has a low position in the galvanic series and may easily suer rom galvanic corrosion i coupled to nobler metals and alloys (see section on galvanic corrosion pg. 64). Designation
Major alloying element
1000-series
Unalloyed (pure) >99% Al
2000-series
Copper is the principal alloying element, though other elements (magnesium) may be specified
3000-series
Manganese is the principal alloying element
4000-series
Silicon is the principal alloying element
5000-series
Magnesium is the principal alloying element
6000-series
Magnesium and silicon are principal alloying elements
7000-series
Zinc is the principal alloying element, but other elements, such as copper, magnesium, chromium, and zirconium may be specified
8000-series
Other elements (including tin and some lithium compositions)
CP: commercial pure (titanium content above 99.5%)
Fig 1.6.19: Major alloying elements o aluminum
Fig 1.6.20: Titanium grades and alloy characteristics
1.6.4 Ceram Ceramics ics
Thermoplastics
Ceramic materials are composed o metallic and non-metallic elements and are typically crystalline in nature. Common technical ceramics are aluminum oxide (alumina - Al2O3), silicon carbide (SiC), tungsten carbide (WC), and silicon nitride (Si3N4). Ceramics are suitable or applications requiring high thermal stability, strength, wear resistance, and corrosion resistance. Disadvantages o ceramics include low ductility and high tendency or brittle ractures. Ceramics are mainly used or making bearings and seal aces or shat seals.
Thermoplastic polymers consist o long polymer molecules that are not cross-linked to each other. They are oten supplied as granules and heated to permit abrication by methods such as molding or extrusion. A wide range is available rom low-cost commodity plastics (e.g. PE, PP, PVC) to high cost engineering thermoplastics (e.g. PEEK) and chemical resistant luoropolymers (e.g. PTFE, PVDF). PTFE is one o the ew thermoplastics that is not meltprocessable. Thermoplastics are widely used or making pump housings or or lining o pipes and pump housings.
1.6.5 Plastics
Thermosets
Some plastics are derived rom natural substances like plants but most types are synthetic. Most synthetic plastics come rom crude oil, but coal and natural gas are also used. There are two main types o plastics: Thermoplastics and thermosets (thermosetting plastics), with thermoplastics being the most common used worldwide. Plastics oten contain additives which transer additional properties to the material. Furthermore, plastics can be reinorced with iberglass or other ibers. These plastics, together with additives and ibers, are also reerred to as composites.
Thermosets harden permanently when heated, as cross-linking hinders bending and rotations. Cross-linking is achieved during abrication using chemicals, heat, or radiation; a process called curing or vulcanization. Thermosets are harder, more dimensionally stable and brittle than thermoplastics and cannot be remelted. Some thermosets include epoxies, polyesters, and polyurethanes. Thermosets are, among other things, used or surace coatings.
Examples o additives ound in plastics: • Inorganic illers or mechanical reinorcement • Chemical stabilizers, e.g. antioxidants • Plasticizers • Flame retardants
Abbreviation
PP PE PVC PEEK PVDF PTFE*
Linear polymer chains
Branched polymer chains
Elastomers
Polymer name Polypropylene Polyethylene Polyvinylchloride Polyetheretherketone Polyvinylidene fluoride Polytetrafluoroethylene
*Trade name: Teflon®
Fig 1.6.21: Overview o polymer names
Thermoplastics
Weakly cross-linked polymer chains
Thermosets Strongly cross-linked polymer chains
Fig 1.6.22: Dierent types o polymers
1. Design Sectiono 1.6pumps and motors Materials 1.1 Pump construction, (10)
1.6.6 Rubber
Ethylene-propylelediene Ethylene-propy lelediene rubber
The term rubber includes both natural rubber and synthetic rubber. Rubbers, also known as elastomers, are lexible long-chain polymers that can be stretched easily to several times their length. Rubbers are cross-linked (vulcanized) but have a low cross-link density, see igure 1.6.22. The crosslink is the key to the elastic or rubbery properties o these materials. The elasticity provides resilience in sealing applications. Dierent components in a pump are made o rubber, such as gaskets and Orings (see section 1.3 on shat seals). In this section, the dierent kinds o rubber qualities and their main properties, in regards to temperature and resistance to dierent kinds o liquid groups, will be presented.
Fluoroelastomers
Nitrile rubber At temperatures up to about 212°F, nitrile rubber (NBR) is an inexpensive material that has a high resistance to oil and uel. Dierent grades o nitrile rubber exist - the higher the acetonitrile (ACN) content, the higher the oil resistance but the poorer the low-temperature lexibility. Nitrile rubbers have high resilience and high-wear resistance but only moderate strength. Further, this rubber has limited weathering resistance and poor solvent resistance. It can generally be used at about -22°F, but certain grades can operate at lower l ower temperatures.
of AbbreviationCommon types Common ofname copper alloys Examples trade name
Ethylene propylelediene (EPDM) has excellent water resistance which is maintained to approximately 248-284°F. This rubber type has good resistance to acids, strong alkalis and polar luids such as methanol and acetone. It has very poor resistance to mineral oil and uel.
Fluoroelastomers (FKM) cover a whole amily o rubbers designed to withstand oil, uel and a wide range o chemicals including non-polar solvents. FKM oers excellent resistance to high temperatures (up to 392°F depending on the grade) in air and dierent types o oil. FKM rubbers have limited resistance to steam, hot water, methanol, and other polar luids. This type o rubber also has poor resistance to amines, strong alkalis and many reons. There are standard and special grades - the latter have improved low-temperature properties or chemical resistance.
Silicone rubber Silicone rubbers (Q) have outstanding properties, such as low compression set in a wide range o temperatures (rom -76°F to 392°F in air), excellent electrical insulation and non-toxic. Silicone rubbers are resistant to water, some acids and oxidizing chemicals. Concentrated acids, alkalines and solvents should not be used with silicone rubbers. In general, these rubber types have poor oil and uel resistance. resistance. However, the FMQ silicone rubber resistance to oil and uel is better than that o types MQ, VMQ, and PMQ.
NBR
Nitrile rubber
Buna-N
EPDM, EPM
Ethylene-propylelediene
Nordel ®
Perluoroelastomers
FKM
Fluoroelastomers
Viton®
MQ, VMQ, PMQ, FMQ
Silicone rubber
Siloprene®
FFKM
Perfluoroelastomers
Chemraz® Kalrez®
Perluoroelastomers (FFKM) have very high chemical resistance, almost comparable to that o PTFE (polytetraluorethylene, e.g. Telon ®). They can be used in high temperatures, but their disadvantages are diicult processing, very high cost and limited use at low temperatures.
Fig 1.6.23: Rubber types
1.6.7 Coatings Protective coatings such as metallic, non-metallic (inorganic) or organic coatings, are a common method o corrosion control. The main unction o coatings, aside rom galvanic coatings such as zinc, is to provide a barrier between the metal substrate and its environment. They allow or the use o normal steel or aluminum instead o more expensive materials. In the ollowing section, the possibilities o preventing corrosion by means o dierent coatings will be examined.
Metallic coatings There are two types o metallic coatings. One is where the coating is less noble than the substrate, and the other, electroplating, is where a more noble metal is applied to the substrate as a barrier layer.
Metallic coatings less noble than the substrate Zinc coatings are commonly used or the protection o steel structures against atmospheric corrosion. Zinc has two unctions. It acts as a barrier coating, and it provides galvanic protection. Should an exposed area o steel o steel occur, the zinc surace preerentially corrodes at a slow rate and protects the steel. The preerential protection is reerred to as cathodic protection. When damage is minimal, the protective corrosion products o zinc will ill the exposed area and stop the attack.
Metallic coatings nobler than the substrat substratee Electroplating o nickel and chromium coatings on steel are nobler than the substrate. Unlike galvanic coatings where the coating corrodes near areas where the base metal is exposed, any void or damage in a barrier coating can lead to an immediate base metal attack.
To protect the base steel, zinc coating sacrifices itself slowly by galvanic action.
Steel coated with a more noble metal, such as nickel, corrodes more rapidly if the coating is damaged.
Fig 1.6.24: Galvanic vs. barrier corrosion protection
1. Design Sectiono 1.6pumps and motors Materials 1.1 Pump construction, (10)
<
Non-metallic coatings (conversion coatings) Conversion coatings are included in non-metallic coatings, also known as inorganic coatings. Co nversion coatings are ormed by a controlled corrosion reaction o the substrate in an oxidized solution. Examples o conversion coatings are anodizing or chromating o aluminum and phosphate treatment o steel. Anodizing is mainly used or surace protection o aluminum, while chromating and phosphating are usually used or pre-treatment to improve paint adhesion and to help prevent the spreading o rust under layers o paint.
Paints As mentioned, paints are an important class o organic coating. Figure 1.6.25 shows several types o organic coatings. A typical paint ormulation contains polymeric binders, solvents, pigments and additives. For environmental reasons, organic solvents are oten replaced by water or simply eliminated, as in powder coating. Painted metal structures usually involve two or more layers o coating applied on a primary coating, which is in direct contact with the metal.
Organic coatings Organic coatings contain organic compounds and are available in a wide range o dierent types. Organic coatings are applied to the metal by methods o spraying, dipping, brushing, lining or electro-coating (paint applied by means o electric current). They may or may not require heat-curing. Both thermoplastic coatings (i.e. polyamide, polypropylene, polyethylene, PVDF and PTFE) and elastomer coatings are applied to metal substrates to combine the mechanical properties o metal with the chemical resistance o plastics, but paints are by ar the most widely used organic coating.
Physical states of common organic coatings Resin type Acrylic Alkyd Epoxy Polyester Polyurethane Vinyl
Solvent- Water- Powder based based coating X X X X X X
X X X X X
Two comp. liquid
X X X X X
X X X
Fig 1.6.25: Physical states o common organic coatings
Chapter 2. Installation and perormance per ormance reading
Section 2.1: Pump installation 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5
New installation Existing installation-replacement Pipe fow or single-pump installation Limitation o noise and vibrations Sound level
Section 2.2: Pump perormance 2.2.1 Hydraulic terms 2.2.2 Electrical terms 2.2.3 Liquid properties
Section 2.1 Pump installation
Accuracy o suited pump type or an installation has signiicant impact on optimum operation. The larger the pumps, the greater the costs with respect to investment, installation, commissioning, operation and maintenance – basically the lie cycle costs (LCC). An extensive product portolio combined with competent advice and ater-sales service is the oundation o a proper selection. The ollowing analysis, recommendations and pump tips are general or any installation but, to a greater extent, relevant or medium to large sized installations. Recommendations or new and existing installations ollow.
2.1.2 Existing installation–replacement
2.1.1 New installation
• •
• I the pipework has not been planned, the selection
Previous pump installation • Pump make, type, speciications including old duty
o a pump type can be based on other primary criteria, such as eiciency, investment costs or liecycle costs (LCC). This will be covered in a later section.
• I the pipework has been planned, pump selection is equivalent to pump replacement in an existing installation.
Tips or optimum pump selection or existing installation ollows.
Pre-investigation o the installation should Pre-investigation include: • Basic pipe low – pipes in and out o the building, e.g. • • • • •
rom the ground, along the loor or rom the ceiling Speciic pipework at the point o installation, e.g. in-line or end-suction, dimensions, maniolds Space availability – width, depth and height Accessibility or maintenance, i.e., doorways Availability/accessibility o lit equipment Floor type, e.g. solid or suspended loor with basement Existing oundation Existing electrical installation
point, shat seal, materials, gaskets, controlling • History, e.g. lietime, maintenance
Future requirements • Desired improvements and beneits • New selection criteria including duty points and operating times, temperature, pressure, liquid specs • Supplier criteria, e.g. availability o spare parts
Advisory • Major changes might be beneicial in long or short term and should be documented, e.g. installation savings, lie cycle costs (LCC), reduced environmenta l impact (noise, vibration accessibility or maintenance)
Selection • Should be based on priorities agreed to by customer For the selection o correct pump type and installation advice, two main areas are important: Pipe low and limitation o noise and vibrations. This will be dealt with on the ollowing pages.
2.1.3 Pipe low or single-pump installation Figure 2.1.1 is based on single-pump installation. In parallel installations, accessibility plays a major role or suitability o a pump choice. Simple pipework with ew bends as possible is the criteria or pump choice in a single-pump installation.
Scores: Best choice Good choice Acceptable choice Not applicable
Pump type
Pipework To the pump:
Along floor
From ground
From ceiling
Wallmounted
A. In-line close-c close-coupled oupled (horizontal or vertical mounting)
B. End-suction End-suction close- couple coupled d (horizontal or vertical mounting)
C. End-su End-sucti ction on long-cou long-couple pled d (only horizontal mounting)
From the pump: Along floor
Best choice
Good choice
Good choice
To ground
Best choice
Good choice
Good choice
To ceiling
Good choice
Best choice
Best choice
Along floor
Good choice
Best choice
Acceptable choice
To ground
Good choice
Best choice
Acceptable choice
To ceiling
Good choice
Best choice
Best choice
Along floor
Best choice
Acceptable choice
Acceptable choice
To ground
Best choice
Good choice
Good choice
To ceiling
Good choice
Best choice
Best choice
Wallmounted
Best choice
Good choice
Not applicable
Fig. 2.1.1 Pipework and pump type
Section 2.1 Pump installation
Accessibility plays a major role in how well a speciic pump choice is suited to an installation o several pumps in parallel. In-line pumps installed in parallel do not always provide the best accessibility because o the pipwork, see igure 2.1.2. End-suction pumps installed in parallel provide better accessibility, see igure 2.1.3.
2.1.4 Limitation o noise and vibrations
Fig. 2.1.2: Three in-line pumps in parallel; limited maintenance access because o pipework
To achieve optimum operation and minimize noise and vibration, vibration dampening o the pump may be necessary. Generally, this should be considered or pumps with motors above 7.5 hp. Smaller motor sizes, however, may also cause noise and vibration due to rotation in the motor and pump and by the low in pipes and ittings. The eect on the environment depends on correct installation and the condition o the entire system. Three ways to limit noise and vibration in a pump installation are: Foundation considerations, dampeners and expansion joints.
Fig. 2.1.3: Three end-suction pumps in parallel; easier maintenance access because o pipework Floor Solid ground
Foundation Floor constructions can be solid or suspended. Fig. 2.1.4: Solid loor construction
Solid – minimum risk o noise due to low transmission o vibrations, see igure 2.1.4. Suspended – risk o loor ampliying the noise. Basement can act as a resonance box, see igure 2.1.5.
Floor Ground foor
Wall
The pump should be installed on a plane on a rigid surace. There are our basic installations or the two types o loor constructions: Floor, oundation, loating oundation and oundation suspended on vibration dampeners.
Basement
Floor Solid ground
Fig. 2.1.5: Suspended loor construction
Floor Direct mounting on loor, hence direct vibration transmission, see igure 2.1.6.
Fig. 2.1.6: Floor
Floor Base plate Pump unit
Foundation Poured directly on concrete loor, see igure 2.1.7.
Floating oundation Resting on a dead material, e.g. sand, hence reduced risk o transmitting vibration, see igure 2.1.8.
Foundation suspended on vibration dampeners Optimum solution with controlled vibration transmission, see igure 2.1.9. The weight o a concrete oundation should be 1.5 x the pump weight. This weight is needed to get the dampeners to work eiciently at low pump speed.
Fig. 2.1.7: Foundation
Floor
Foundation Base plate Pump unit
Floor Sand
Foundation Base plate Pump unit
Fig. 2.1.8: Floating oundation
Fig. 2.1.9: Foundation suspended on vibration dampeners
Floor Vibration dampeners Foundation Base plate Pump unit
Pump unit
Fig. 2.1.10: 2.1.10: The same oundation rules apply to vertical in-line pumps
Foundation Vibration dampeners Floor
Section 2.1 Pump installation
Dampeners Vibration dampener selection requires the ollowing data:
pressure loss on the pressure side. At high water velocities (16.4 t/s or greater), it is best to install larger expansion joints, corresponding to the pipework.
• Forces acting on the dampener • Motor speed with consideration o speed control • Required dampening in % (suggested value is 70%) Dampener selection varies rom installation to installation. An incorrect selection may increase the vibration level. The supplier should, thereore, size vibration dampeners. Pumps installed with vibration dampeners should always have expansion joints itted at both the suction and the discharge side to prevent the pump rom being supported by the langes.
Expansion joints Expansion joints are installed to:
• Absorb expansions/contractions in the pipework caused by liquid temperature changes
• Reduce mechanical strain in connection with pressure waves in the pipework
• Isolate mechanical noise in the pipework (not or metal bellows expansion joints) Expansion joints should not be installed to compensate or inaccuracies in the pipework, such as center displacement or misalignment o langes. Expansion joints are itted at a minimum distance o 1 to 1.5 times the pipe diameter rom the pump on the suction side as well as on the discharge side. This prevents the development o turbulence in the expansion joints, resulting in better suction conditions and a minimum
Expansion joint
Foundation Pump unit
Base plate Vibration dampeners Floor
Fig. 2.1.11: Installation with expansion joints, vibration dampeners and ixed pipework
Figures 2.1.12-2.1.14 show examples o rubber bellows expansion joints with or without tie bars. Fig. 2.1.12: Rubber bellows expansion joints with tie bars
Expansion joints with tie bars can be used to minimize the orces caused by the expansion joints and are recommended or sizes larger than our inches. An expansion joint without tie bars will exert orce on the pump langes, which in turn aects the pump and the pipework.
Fig. 2.1.13: Rubber bellows expansion joints without tie bars
The pipes must be ixed so that they do not stress the expansion joints and the pump, see igure 2.1.11. The ixed points should always be placed as close to the expansion joints as possible. Follow the expansion joint supplier’s instructions.
Fig. 2.1.14: Metal bellows expansion joints with tie bars
At temperatures above 212°F combined with a high pressure, metal bellows expansion joints are oten preerred, due to the risk o rupture. Lp (dB)
Pain threshold
120 Threshold o hearing
2.1.5 Sound level The sound level (L) in a system is measured in decibel (dB). Noise is unwanted sound. The level o noise can be measured in the ollowing three ways:
100 Music
80 60
Speech 40 20 0
1. Pressure – Lp : The pressure o the air waves 2. Power – Lw : The power o the sound 3. Intensity - L l: The power per m2 (will not be covered in this book) It is not possible to compare the three values directly, but it is possible possi ble to calculate between them based on standards. A rule-o-thumb is:
Smaller pumps, e.g. 2 hp: Lw = LP + 11 dB Larger pumps, e.g. 150 hp: Lw = LP + 16 dB
20
50 10 100 20 200 500Hz 1
2
5
10 20 20kHz Frequency kHz
Fig. 2.1.15: Threshold o hearing vs. requency
Section 2.1 Pump installation
Sound levels are indicated as pressure when they are below 85 dB(A) and as power when exceeding 85 dB(A). Noise is subjective and depends on a person´s ability to hear. Thereore, the above mentioned measurements get weight according to the sensitivity o a standard ear, see igure 2.1.15. The weighting is known kno wn as A-weighting [dB(A)], expressed as: LpA, and the measurements are adjusted depending on requency. In some cases the weighting increases and in other cases it decreases, see igure 2.1.16. Other weightings are known as B and C but they are used or other purposes not covered in this book.
dB (A)
10 0 -10 -20 -30 -40 -50 -60 -70 -80 10
100
1000
10000 Hz
Fig. 2.1.16 A-weighting curve
15
In the case o two or more pumps in operation, the sound level can be calculated. I the pumps have the same sound level, the total sound level can c an be calculated by adding the value, see igure 2.1.17. For example, two pumps is Lp + 3 dB, three pumps is Lp + 5 dB. I the pumps have dierent sound levels, values rom igure 2.1.18 can be added. Indications o sound level should normally be stated as ree ield conditions over relecting surace, meaning the sound level on a hard loor with no walls. Guaranteeing values in a speciic room in a speciic pipe system is diicult because these values are beyond the reach o the manuacturer. Certain conditions could have a negative impact (increased sound level) or a positive impact on the sound level. Recommendations to installation and oundation can be given to eliminate or reduce the negative impact o sound level.
10
5
4
8
12
16
20
24
Fig. 2.1.17 Increase o the total sound pressure level with equal sources
3
2.5
2
1.5
Experience values: 1
Rise o + 3 dB + 5 dB +10 dB
Perceived as: Slightly noticeable Clearly noticeable Twice as loud
0.5
2
4
6
8
10
Fig. 2.1.18 Increase o the total sound pressure level with dierent sources
Section 2.2 Pump perormance
When examining a pump, several things should be evaluated. For example, i the pump is rusty or makes abnormal noise, a number o values must be identiied in order to determine i the pump is perorming properly. On the next pages, three values are presented or examining a pump’s perormance: Hydraulic terms, electrical terms, mechanical terms and liquid properties.
2.2.1 Hydraulic terms Flow, pressure and head are the most important hydraulic terms pertinent to pump perormance.
Flow Flow is the amount o liquid that passes through a pump within a certain period o time. Volume low and mass low are the two low parameters considered or a perormance reading.
Qm = ρ . Q
; Q =
Qm ρ
Volume low Volume low (Q) is read rom a pump curve - or, put in another way, a pump can move a given volume per unit o time, measured in gallons per minute, no matter the density o the liquid. For water supply, or example, volume low is the most important parameter because a certain volume o water is needed or drinking or irrigation. Throughout this book the term low reers to volume low.
Unit
Volume flow Q
GPM
Density
lb/ft3
62.30
58.86
lb/h
22000
20730
lb/s
6.1
5.7
Mass flow Qm
Fig. 2.2.1: Calculation examples
Mass low Mass low (Q m) is the mass which a pump moves per unit o time and is measured in pounds per second. The liquid temperature has an inluence on how big a mass low can move per unit o time since the liquid density changes with the temperature. In heating, cooling and air-conditioning systems, the mass low is essential to identiy because the mass is the carrier o energy (see section on Heat Capacity).
Water
Examples
at 68°F
at 248°F 44.02
Section 2.2 Pump perormance
Pressure Pressure (p) is a measure o orce per unit area. Total Total pressure is the sum o the static pressure and the dynamic pressure:
Later in this chapter, dynamic pressure in connection with determining the head o a pump will be discussed.
psta psta
Q
Static pressure Static pressure psta is the pressure measured with a pressure gauge placed perpendicular to the low or in a non-moving liquid, see igure 2.2.2.
ptot
pdyn psta ptot
ptot
Fig. 2.2.2: How to determine the static pressure Psta, the dynamic pressure Pdyn and the total pressure Ptot
Dynamic pressure Dynamic pressure p dyn is caused by liquid velocity and is calculated by the ollowing ormula:
1 2 where: ρ is the density o the liquid in [lb/t 3] v is the velocity o the liquid in [t/s]
D1
v1
1 2 So, an increase in pipe diameter, as the one shown in igure 2.2.2 results in an increase in the static head which is measured with the pressure gauge p 2. In most pumping systems, the dynamic pressure pdyn has a minor impact on the total pressure. For example, i the velocity o a water low is 14.7 t/s, the dynamic pressure is around 1.45 psi, which is considered insigniicant in many pumping systems.
v2
A P
Dynamic pressure can be converted into static pressure by reducing the liquid velocity and vice versa. Figure 2.2.3 shows a part o a system where the pipe diameter increases rom D1 to D2 resulting in a decrease in liquid speed rom v1 to v2. Assuming that there there is no riction riction loss in the system, the sum o the static pressure and the dynamic pressure is constant throughout the horizontal pipe.
p2
p1
D2
B ptot psta
pdyn
Fig. 2.2.3: The static pressure increases i the liquid velocity is reduced. The igure applies or a system with insigniicant riction loss
Measuring pressure Pressure is measured in psi (Ib/in²), or bar (105 Pa). When dealing with pressure, it is important to know the point o reerence or the pressure measurement. Two types o pressure are essential with pressure measurement: Absolute pressure and gauge pressure.
Conversion table for pressure units designation
psi
kPa
Absolute pressure (Pabs) is deined as the pressure above absolute vacuum, 0 atmospheres, that is the absolute zero or pressure. Usually, “absolute pressure” is used in cavitation calculations.
bar
atm
1 psi
1
6.895
2 . 3 07
0.703
0.068
0. 069
1 kPa
0.145
1
0 . 335
0.102
0.0097
0.01
1 feet of H 2O
0.4335
2.969
1
0.305
0.0295
0.03
1 m of H 2O
1.422
9.806
3.281
1
0.097
0.098
1 m H2O
14.696
101.325 33.9
10.333
1
1.013
33.5
10.197
0.987
1
1 bar 14.504 * Physical atmosphere
Absolute pressure
ft of H 2O m of H 2O
100
Fig. 2.2.4: Conversion table or or pressure units
Gauge pressure Gauge pressure (Pg), oten reerred to as overpressure, is higher than normal atmospheric pressure (1 atm). Normally, pressure pressur e p is stated as gauge pressure because most sensor and pressure gauge measurements account or the pressure dierence between the system and the atmosphere. Throughout this book the term pressure reers to gauge pressure.
Head The head (H) o a pump is an expression o how high the pump can raise a liquid. Head is measured in eet (t) and is independent o the liquid density. The ollowing ormula shows the relationship between pressure (p) and head (H):
2.307 SG where : H is the head in [t] p is the pressure in psi SG is the speciic gravity o the liquid Pressure p is measured in [psi].
Other pressure units are used as well, see igure 2.2. 2. 2.4. 4. The The relationship rela re lati tion onsh ship ip between betw be twee een n pressure pres pr essu sure re and and head head is shown in igure 2.2.5, where a pump handles our dierent liquids.
t f 1 .
t f 5 . 2 4
t f
t f 1 . 4 3
6 2
4 . 5 3
Brine at 68°F
Water at 68°F
Water at 203°F
Diesel oil at 68°F
SG = 1.3
SG = 0.997
SG = 0.96
SG = 0.80
14.7 psi = 26.1 t
14.7 psi = 34.1t
14.7 psi = 35.4 t
14.7 psi = 42.5 t
1 4.7 p si
14.7 psi
14 .7 psi
14 .7 p si
Fig. 2.2.5: Pumping our dierent liquids at 14.7 psi at the discharge side o the pump results in our dierent heads (t), hence our dierent duty points
Section 2.2 Pump perormance
How to determine the head The pump head is determined by reading the pressure on the langes o the pump p2, p1 and then converting the values into head, see igure 2.2.6. However, However, i a static dierence in head is present between the two measuring points, as it is in the case in igure 2.2.6, it is necessary to compensate or the dierence. And i the port dimensions o the two measuring points dier rom one another, the actual head has to be corrected or this as well.
The correction due to the dierence in port diameter is caused by the dierence in the dynamic pressure. Instead o calculating the correction rom the ormula, the contribution can be read in a nomogram, see appendix F. v2 D2
p2
The actual pump head H is calculated by the ollowing ormula:
v1 h2
2.31
D1 p1
h1
SG where : H is the actual pump head in [t] p is the pressure pressure at the langes langes in [t] SG is the speciic gravity gravity o the liquid g is the acceleration acceleration o gravity in [t/s2] h is the static height in [t] v is the liquid velocity in [t/s] [t/s] The liquid velocity v is calculated by the ollowing ormula:
0.4085
where: v is the velocity in [t/s] Q is the volume low in [GPM] D is the port diameter in [in] A is the area Combining these two ormulas, head, H, depends on the ollowing actors: The pressure measurements p1 and p2, the dierence in static height between the measuring points h2-h1, the low through the pump Q, and the diameter o the two ports D1 and D2 .
2.31
0.4085 Q SG
Fig. 2.2.6: Standard end-suction pump with dimension dierence on suction and discharge ports
Calculation example
v2 = 17.8 ft/s2
A pump o the same type as the one shown in igure 2.2.7 is installed in a system with the ollowing data: Q = 1057 GPM p1 = 7.25 psi p2 = 15.9 psi Liquid: Water at 680F
p2 = 15.9 psi h2 - h1 = 1 ft
D1 = 5.9 in v1 = 12.3 ft/s2
Suction port diameter D1 = 6 in Discharge port diameter D 2 = 5 in The dierence in height between the two ports where the pressure gauges are installed is h 2-h1 = 1 t We are now able to calculate the head o the pump:
2.31
0.4085 Q
SG
2.31 (15.9 - 7.25) 1.0
D2= 4.9 in
1
0.4 .408 0855 10 10557
4.9
5.9
19.98 1 5.82 26.80 ft
As it appears rom the calculation, the pressure dierence measured by pressure gauges is about 1 t lower than what the pump is actually perorming. The deviation is caused by the dierence in height between the pressure gauges (1 t) and by the dierence in port dimensions, which in this case is 1 inch.
p1 = 7.25 psi
Fig. 2.2.7: Standard end-suction pump with dierent dimensions o suction and discharge ports (Example)
Section 2.2 Pump perormance
I the pressure gauges are placed at the same static height or i a dierential pressure gauge is used or the measurement, it is not necessary to compensate or the dierence in height (h 2-h1). With in-line pumps, where inlet and outlet are placed at the same level, the two ports oten have the same diameter. For these types o pumps a simpliied simpli ied ormula is used to determine the head:
2.31 ( SG
(
p1
p2
h1
h2
Fig.2.2.7.a: Inline pump with same static height on inlet and outlet. h2 = h1
H = head in ft P = psi SG = specific gravity
Dierential pressure The dierential dierential pressure pressure (∆ p) is the pressure dierence between the pressures measured at two points, that is, the pressure drops across acros s valves in a system. Dierential pressure is measured in the same units as pressure.
Dry cooler
h
System pressure The system pressure is the static pressure, which reers to when the pumps are not running. System pressure is important to consider when dealing with a closed system. The system pressure, measured in eet in the lowest point, must always be higher than the height o the system to ensure that the system is illed with liquid and can be vented properly.
Chiller Hsyst Hsyst > h
Fig.2.2.8: The system pressure Hsta in a closed system has to be higher than the physical height o the installation
Cavitation Cavitation in a pump occurs when the suction pressure is lower than the vapor pressure o the liquid pumped, see igures 2.2.9 and 2.2.10. When the pressure on the suction side o the pump drops below the vapor pressure o the pumped liquid (igure 2.2.10 yellow dot), vapor bubbles orm. As the pressure in the pump rises, the bubbles collapse releasing shock waves (igure 2.2.10 red dot) which can damage impellers. The rate o damage depends on the properties o the impeller material. Stainless steel is more resistent to cavitation than bronze, and bronze is more resistant than cast iron, see section 1.6.3. Additional damage to bearings, shat seals and welds may occur due to increased noise and vibration caused by cavitation. This damage is oten only detected when the pump is disassembled. Pump perormance is harmed by cavitation due to decreases in both low (Q) and head (H), see igure 2.2.11.
Net Positive Suction Head To calculate the risk o cavitation, the Net Positive Suction Head Required (NPSHr) or the pump is compared with the Net Positive Suction Head Available (NPSHa) o the system. NPSHr, which is the amount o suction head required to ensure the pump perorms at ull capacity, is determined by the manuacturer and typically included on the perormance curve. NPSH a is a unction o the system in which the pump will be applied and is calculated as ollows:
hmax = Maximum suction head Hb = Atmospheric pressure at the pump site; this is the theoretical maximum suction lit, see igure 2.2.13 H = Friction loss in the suction pipe NPSHr = Net Positive Suction Head read at the NPSH curve at the highest operational low, see igure 2.2.12.
a = Front o impeller vanes b = Back o impeller vanes
a b Imploding vapor bubbles Fig.: 2.2.9: Implosion o cavitation bubbles on the back o impeller vanes p
] a P [
a
a = Front o impeller vanes b = Back o impeller vanes
b
e r u s s
e r P
p1
p
Vaporpressure
Impeller inlet
Impeller outlet
Fig.: 2.2.10: Development o pressure through a centriugal pump H
NPSHa = Hb + Hs — H — Vp
Hb = Barometric Pressure, in eet absolute Hs = Suction Head, in eet absolute (positive or negative) H = Friction loss in suction piping, in eet absolute Vp = Vapor pressure at the maximum operating temperature, in eet absolute
Curve when pump cavitates
Q
Fig.: 2.2.11: Pump curve when pump cavitates H
NPSHa must be greater than the NPSHr to avoid cavitation.
Calculation o the risk o cavitation To avoid cavitation, the ollowing ormula is used to calculate the maximum suction head:
NPSH
Q
hmax = Hb — H — NPSHr — Hv — Hs
Fig.: 2.2.12: NPSH - curve
Section 2.2 Pump perormance
The NPSH value indicates to what extent the pump is unable to create absolute vacuum, that is to raise a ull water column 33.89 t above sea level, see igure 2.2.13.
Height above sea level (ft)
Barometric pressure p (psi)
Water column H (ft)
Boiling point of water (°f)
0
14.692
3 3. 8 9
212
1640.4
13.567
31.92
210.2
3280.8
13.039
30.05
204.8
6561.6
11.531
26.57
199.4
NPSH can either be considered in terms o NPSHr (required) or NPSHa (available). NPSHrequired The required suction head or the pump NPSHavailable The available suction head in the system
Hs – Saety actor. H s depends on the situation and normally varies between 1.5 t and 3 t. For typical curve or liquid containing gas see igure 2.2.15.
b
Fig.: 2.2.13: Barometric pressure above sea level
The NPSH value o a pump is determined by Hydraulic Institute testing standards and is made as ollows. The suction head is reduced while the low is kept at a constant level. When the dierential pressure has decreased by 3%, the pressure at the pump’s suction side is read and the NPSH value o the pump is deined. The testing is repeated at dierent lows, orming the basis o the NPSH curve. Hv – Vapor pressure o the liquid. For more inormation concerning vapor pressure o water, go to Appendix D.
b
tm (°F ) 370
h
328
320
259
300
270
148 131 115 98 82
250
66
230
49 39 33 26
212
NPSH
194
Hb
176 158 Hv
140 122 104
Fig.: 2.2.14: System with indication o the dierent values that are important in connection with suction calculations
86 68 50 32
2.2.2 Electrical terms To examine a pump’s perormance, a range o values must be considered. In this section the most important electrical values are presented: Power consumption, voltage, current and power actor.
360
280
Hf
Hv (ft) 413
] t f [ H
NPSH Liquid with air
Vented liquid
Q[GPM]
Fig.: 2.2.15: Typical NPSH curve or liquid containing gas
20 16 13 10 6.6 4.9 3.3 2.6 2.0 1.3 0.9 0.7 0.3
Power consumption Pumps are made o several components, see gure 2.2.16. The power consumption (P) o the dierent components is designated as ollows:
P1 P1
The power input rom the mains, or the amount o power the consumer must purchase.
P2
The power input to the pump, or the power output rom the motor, oten reerred to as shat power or brake horsepower (Bhp).
PH
Hydraulicpower;thepowerthatthepump transers to the liquid in the orm o low and head, also known as water hp (Whp).
P2
For the most common pump types, the term power consumption normally reers to P2. Power is measured in horsepower (hp).
Eiciency
PH
Eciency (η) normally only covers the eciency o the pump part, ηP. A pump’s eciency is determined by several actors, including the shape o the pump housing, the impeller and diuser design and the surace roughness. For typical pump units consisting o both pump and electric motor, the total eciency ηT also includes the eciency o the motor: Fig. 2.2.16: Pump unit with indication o dierent power consumption levels
I a requency converter is also included, the eciency o the entire unit must include the eciency o the requency converter ( ηc ):
Section 2.2 Pump perormance
Voltage Like pressure drives low through a hydraulic system, voltage (v) drives a current (I) through an electrical circuit. Voltage is measured in volts (V) and can be direct current (DC), e.g. 1.5 V battery – or alternating current (AC), e.g. electricity supply or houses, etc. Normally, pumps are supplied with AC voltage supply.
L1 L2 L3 N
} }
480V Three-phase supply 230V Single-phase supply
Ground Fig. 2.2.17: Mains supply, e.g. 3 x 480 V
The layout o an AC main supply diers rom one country to another. The most common layout is our wires with three phases (L1, L2, L3) and a neutral (N). A ground connection is added to the system as well, see igure 2.2.17. For a 3x480 V/230 V main supply, the voltage between any two o the phases (L1, L2, L3) is 480 V. The voltage between one o the phases and neutral (N) is 230 V. The ratio between the phase-phase voltage and the phase-neutral voltage is determined by the ormula at right.
The ratio between the phase-phase voltage and the phase-neutral voltage is:
Current Current (I) is the low o electricity and is measured in ampere (A). The amount o current in an electrical circuit depends on the supplied voltage and the resistance/ impedance in the electrical cir cuit.
Power and power actor Power (P) consumption is o high importance when it comes to pumps. For pumps with standard AC motors, the power input is ound by measuring the input voltage and input current and by reading the value cosj on the pump motor nameplate. The term cosj is the phase angle between voltage and current and is reerred to as power actor (PF). The power consumption P1 can be calculated by the ormulas shown at right or a single-phase or a three-phase motor.
AC single-phase motor, e.g. 1 x 230 V
AC three-phase motor, e.g. 3 x 480 V
2.2.3 Liquid properties
Viscosity
When making system calculations, the ollowing liquid properties should be considered: Liquid temperature, speciic gravity, heat capacity, and viscosity.
Kinematic viscosity is measured in centiStokes [cSt] (1 cSt = 10-6 m2/s). The unit [SSU] Saybolt Universal is also used in connection with kinematic viscosity. For kinematic viscosity above 60 cSt, the Saybolt Universal viscosity is calculated by the ollowing ormula: [SSU] = 4.62 . [cSt]
Liquid temperature The liquid temperature (t,T) is measured in °F (Fahrenheit), °C (Celcius), or K (Kelvin). Temperature units o °C and K are actually the same, but 0°C is the reezing point o water and 0°K is the absolute zero; that is -273.15°C, the lowest possible temperature. The calculation between Fahrenheit and Celcius is °F = °C . 1.8 + 32. Hence, the reezing point o water is 0°C and 32°F, and the boiling point is 100°C and 212°F.
18.42
Btu/lbm °F 0% pure water
16.74
20%
15.07
34% 44%
13.39
52%
11.72
Speciic Gravity The Speciic Gravity (SG) is a dimensionless unit deined as the ratio o density o the material to the density o water at a speciied temperature o 68°F. See appendix K.
Liquid heat capacity The heat capacity (C p) shows how much additional energy a liquid can contain per mass when it is heated. Liquid heat capacity depends on temperature, see igure 2.2.18. Heat capacity is considered in systems or transporting energy, such as heating, air-conditioning and cooling. Mixed liquids, such as glycol and water or air-conditioning, have a lower heat capacity than pure water, so higher low is required to transport the same amount o energy.
10.04 8.37 -40
-4
32
68
104
140
176
212
Fig. 2.2.18: Heat capacity vs. temperature or ethylene glycol
248°F
Chapter 3. System hydraulics
Section 3.1: System characteristics 3.1.1 Single resistances 3.1.2 Closed and open systems
Section 3.2: Pumps connected in parallel and series 3.2.1 Pumps in parallel 3.2.2 Pumps conn connected ected in series
Section 3.1 System characteristics
Previously, in section 1.1.2, the basic characteristics o pump perormance curves were discussed. In this chapter the pump perormance curve at dierent operating conditions as well as a typical system characteristic will be examined. Finally, the interaction between a pump and a system will be discussed. System characteristic describes the relation between low (Q) and head (H). The system characteristic depends on the type o system in question, closed or open.
• Closed systems A closed system is a circulating system like heating or air-conditioning systems, where the pump has to overcome the riction losses in the pipes, ittings, valves, etc. in the system.
• Open systems An open system is a liquid transport system like a water supply system where the pump must address the static head as well as overcome o vercome the riction losses in the pipes and components. When the system characteristic is drawn in the same system o co-ordinates as the pump curve, the duty point o the pump can be determined as the point o intersection o the two curves, see igure 3.1.1. Open and closed systems consist o resistances (valves, pipes, heat exchanger, etc.) connected in series or parallel, which altogether aect the system characteristic. Following is a discussion on how these resistances aect the system characteristic.
Fig. 3.1.1: The point o intersection between the pump curve and the system characteristic is the duty point o the pump
3.1.1 Single resistances Every component in a system constitutes a resistance against the liquid low which leads to a head loss. The ollowing ormula is used to calculate the head loss:
∆H = k . Q2 k is a constant, which depends on the component in question, and Q is the low through the component. As it appears rom the ormula, the head loss is proportional to the low to the second power. So, i it is possible to lower the low in a system, a substantial reduction in the pressure loss occurs.
Resistances connected in series The total head loss in a system consisting o several components connected in series is the sum o head losses that each component represents. Figure 3.1.2 shows a system consisting o a valve and a heat exchanger. I we do not consider the head loss in the piping between the two components, the total head hea d loss, loss, ∆ Htot, is calculated by adding the two head losses:
∆Htot = ∆H1 + ∆H2 Figure 3.1.2 shows how the resulting curve will look and what the duty point will be i the system is a closed system with only these two components. As it appears rom the igure, the resulting characteristic is ound by adding the the individual head head losses, ∆ H, at a given low Q. The igure shows that the more resistance in the system, the steeper the resulting system curve will be.
Fig. 3.1.2: The head loss or two components connected in series is the sum o the two individual head losses
Section 3.1 System characteristics
Resistances connected in parallel Contrary to connecting components in series, connecting components in parallel results in a more lat system characteristic. This is because the components installed in parallel reduce the total resistance in the system, and thereby the head loss. The dierential pressure across the components connected in parallel is always the same. The resulting system characteristic is deined by adding all the components’ individual low rates or a speciic ∆ H. Figure 3.1.3 shows a system with a valve and a heat exchanger connected in parallel. The resulting low can be calculated by the ollowing ormula or a head loss equivalent equivalent to ∆ H
Q tot = Q 1 + Q2
Fig. 3.1.3: Components connected in parallel reduce the resistance in the system and result in a more lat system characteristic
3.1.2 Closed and open systems As mentioned previously, pump systems are split into two types: Closed and open systems. This section will examine the basic characteristics o these systems.
Closed systems Typically, closed systems are systems which transport heat energy in heating systems, air-conditioning systems and process cooling systems. A common eature o these closed systems is that the liquid is circulated and is the carrier o heat energy. Heat energy is what the system must transport. Closed systems are characterized as systems with pumps that overcome the sum o riction losses which are generated by all the components. Figure 3.1.4 shows a schematic drawing o a closed system where a pump circulates water rom a heater through a control valve to a heat exchanger.
Fig. 3.1.4: Schematic drawing o a closed system
All these components, along with the pipes and ittings, result in a system characteristic as shown in igure 3.1.5. The required pressure in a closed system (which the system curve illustrates) is a parabola starting at the point (Q,H) = (0,0) and is calculated by the ollowing ormula:
H = k . Q2 As the ormula and curve indicate, the pressure loss is approaching zero when the low drops.
Fig. 3.1.5: The system characteristic or a closed system is a parabola starting at point (0,0)
Open systems Open systems use the pump to transport liquid rom one point to another, e.g. water supply irrigation and industrial process systems. In these systems, the pump deals with the static head o the liquid and must overcome the riction losses in the pipes and the system components. There are two types o open systems: • Open systems where the the total required static head head is positive. • Open systems where the the total required static head head is negative.
Fig. 3.1.6: Open system with positive static head
Open system with positive static head Figure 3.1.6 shows a typical open system with positive static head. A pump transports water rom a break tank at ground level up to a roo tank on the top o a building. The pump must provide a head higher than the static head o the water (h), as well as the necessary head to overcome the total riction loss between the two tanks in piping, pi ping, ittings, valves, etc. (H ). The pressure loss depends on the rate o low, see igure 3.1.7.
Q1
Q
Fig. 3.1.7: System characteristic together with the pump perormance curve or the open system in igure 3.1.6
Section 3.1 System characteristics
Figure 3.1.7 shows that, in an open system, no water lows i the maximum head (Hmax) o the pump is lower than the static head (h). Only when H > h will water start to low rom the break tank to the roo tank. The system curve also shows that the lower the low rate, the lower the riction loss (H ) and, consequently, the lower the power consumption o the pump. So, the low (Q1) and the pump size have to match the need or the speciic system. This is a general rule or liquid transport systems: A larger low leads to a higher pressure loss, whereas a smaller low leads to a smaller pressure loss and, consequently, a lower energy consumption.
Open system with negative static head A typical example o an open system with negative required head is a pressure booster system, as in a water supply system. The static head (h) rom the water tank brings water to the consumer. The water lows, although the pump is not running. The dierence in height between the liquid level in the tank and the altitude o the water outlet (h) results in a low equivalent to Q o. However, the head is insuicient to ensure the required low (Q 1) to the consumer, so the pump has to boost the head to the level (H1) in order to compensate or the riction loss (H ) in the system. The system is shown in igure 3.1.8, and the system characteristic and the pump perormance curve are shown in igure 3.1.9.
Fig. 3.1.8: Schematic drawing o a open system
The resulting system characteristic is a parabolic curve starting at the H-axes in the point (0,-h). The low in the system depends on the liquid level in the tank. I the water level in the tank is reduced, the height (h) is reduced. This results in a modiied system characteristic and a reduced low in the system, see igure 3.1.9.
Fig. 3.1.9: System characteristic and the pump perormance curve or the open system shown in igure 3.1.8
Section 3.2 Pumps connected in parallel and series
To increase total pump perormance in a system, pumps are oten connected in parallel or series. This section will ocus on these two ways o connecting pumps.
3.2.1 Pumps in parallel Pumps connected in parallel are oten used when: • The required low is higher than one single pump
can supply • The system has variable low requirements which are met by switching parallel-connected pumps on and o Normally, pumps connected in parallel are o similar type and size. However, the pumps can be o dierent size, or one or several can be speed-controlled, and thereby have dierent perormance curves.
,
To avoid bypass circulation in pumps that are not running, a check valve is connected in series with each pump. The resulting perormance curve or a system consisting o several pumps in parallel is determined by adding the low, which the pumps deliver at a speciic head. Figure 3.2.1 shows a system with two identical pumps connected in parallel. The system’s total perormance curve is determined by adding Q1 and Q2 or every value o head which is the same or both pumps, H1=H2 . Because the pumps are identical, the resulting pump curve has the same maximum head, H max, but the maximum low, Qmax, is double. For each value o head, the low is the double as or a single pump in operation:
Q = Q 1 + Q2 = 2 Q 1 = 2 Q 2
Fig. 3.2.1: Two pumps connected in parallel with similar perormance curves
Section 3.2 Pumps connected in parallel and series
Figure 3.2.2 shows two dierent sized pumps connected in parallel. When adding Q 1 and Q2 or a given head H1=H2, the resulting perormance curve is deined. The hatched area in igure 3.2.2 shows that P1 is the only pump to supply in that speciic area because it has a higher maximum head than P 2.
Speed-controlled pumps connected in parallel For varying low demand, speed-controlled pumps connected in parallel oer eicient pump perormance. This method is common to water supply and pressure boosting systems. Later in chapter 4, speed-controlled pumps will be discussed in detail.
Fig 3.2.2: Two pumps connected in parallel with unequal perormance curves
A pumping system with two speed-controlled pumps with the same perormance curve covers a wide perormance range, see igure 3.2.3. A single pump covers the required pump perormance up to Q1. Above Q1 both pumps must operate to meet the perormance needed. I both pumps are running at the same speed, the resulting pump curves look like the orange curves shown in igure 3.2.3. Note that the duty point at Q 1 is reached with one pump running at ull speed. The duty point can also be achieved when two pumps are running at reduced speed, see igure 3.2.4 (orange curves). The igure also compares eiciency. The duty point or one pump running at ull speed results in low pump eiciency because the duty point is located ar out on the pump curve. The total eiciency is much higher when two pumps run at reduced speeds, although the maximum eiciency o the pumps decreases slightly at reduced speeds. Even though one single pump is able to maintain the required low and head, it is sometimes necessary due to eiciency and, thus, energy consumption to use both pumps at the same time. Whether to run one or two pumps depends on the actual system characteristic and pump type.
Fig. 3.2.3: Two speed-controlled pumps connected in parallel (same size). The orange curve shows the perormance at reduced speed
Fig. 3.2.4: One pump at ull speed compared to two pumps at reduced speed. In this case the two pumps have the highest total eiciency
3.2.2. Pumps connected in series Normally, pumps connected in series are used in systems where high pressure is required. This is also the case or multistage pumps that are based on the series principle; that is, one stage equals one pump. Figure 3.2.5 shows the perormance curve o two identical pumps connected in series. The resulting perormance curve is made by marking the double head or each low value in the system o co-ordinates. This results in a curve with the double maximum head (2⋅Hmax) and the same maximum low (Qmax) as each o the single pumps.
Fig. 3.2.5: Two equal sized pumps connected in series
Figure Figu re 3. 3.2. 2.6 6 sh show ows s tw two o di difffer eren ent t si size zed d pu pump mps s connectedinseries.Theresultingperformancecurve isdeterminedbyaddingH 1andH 2atagivencommon flowQ1=Q2. Thehatchedareainfigure3.2.6showsthatP 2isthe only onl y pum pump p to sup supplyin plyin tha that t are area a beca because use it has a highermaximumflowthanP 1.
Q
Fig. 3.2.6: Two dierent sized pumps connected in series
As discussed in section 3.2.1, unequal pumps can be a combination o dierent sized pumps or o one or several speed-controlled pumps. The combination o a ixed-speed pump and a speed-controlled pump connected in series is oten used in systems where a high and constant pressure is required. The ixed-speed pump supplies the liquid to the speedcontrolled pump whose output is controlled by a pressure transmitter, (PT), see igure 3.2.7. Fig. 3.2.7: Equal sized ixed-speed pump and speed-controlled speed-controlled pump connected in series. A pressure transmitter PT together with a speed controller is making sure that the pressure is constant at the outlet o P2.
Chapter 4. Perormance adjustment o pumps
Section 4.1: Adjusting pump perormance 4.1.1 Throttle control 4.1.2 Bypass control 4.1.3 Modiying impeller diameter diameter 4.1.4 Speed control 4.1.5 Comparison o adjustment adjustment methods 4.1.6 Overall eciency o the pump system 4.1.7 Example: Relative power consumption consumption when the fow is reduced by 20%
Section 4.2: Speed-controlled pump solutions 4.2.1 Constant pressure control 4.2.2 Constant temperature temperature control 4.2.3 Constant dierential pressure in a circulating system 4.2.4 Flow-compensated dierential pressure control
Section 4.3: Advantages o speed control
Section 4.4: Advantages o pumps with integrated requency converter 4.4.1 Perormance curves o speed-controlled pumps 4.4.2 Speed-controlled pumps in dierent systems
Section 4.5: Frequency converter 4.5.1 Basic unction and and characteristics 4.5.2 Components o the requency requency converter 4.5.3 Special conditions regarding requency converters
Section 4.1 Adjusting pump perormance
When selecting a pump or a given application, it is important to choose one where the duty point is in the high-eiciency area o the pump. Otherwise, the power consumption o the pump is unnecessarily high, see igure 4.1.1. However, sometimes it is not possible to select a pump that its the optimum duty point because the requirements o the system change or the system curve changes over time. Thereore, it may be necessary to adjust the pump perormance so that it meets the changed requirements. The most common methods o changing pump perormance are: • Throttle control • Bypass control • Modiying impeller diameter • Speed control
Choosing a method o pump perormance adjustment is based on an evaluation o the initial investment along with the operating costs o the pump. All methods can be carried out continuously during operation apart rom the modiying impeller diameter–method. Oten, oversized pumps are selected or the system. It is then necessary to limit the perormance – primarily the low rate, and in some applications, the maximum head. The our adjusting methods are discussed on the ollowing pages.
η
H
[ft]
[%]
60 50 40 30
70 60
20
50 40
10
20
30 10 0 0
5
10
15
20
25
30
35
40 Q [GPM] 0
Fig.: 4.1.1: When selecting a pump it is important to choose one where the duty point is within the high eiciency area.
4.1.1 Throttle control A throttle valve may be placed in series with the pump, permitting the duty point to be adjusted. Throttling results in a low reduction, see igure 4.1.2. The throttle valve adds resistance to the system, raising the system curve. Without the throttle valve, the low is Q2. With the throttle valve connected in series with the pump, the low is reduced to Q 1.
Hp Throttle valve
System Hv
Hs
H Pump
Throttle valves can be used to limit the maximum low. In the example, the low will never be higher than Q 3 even i the original system curve is completely lat, meaning there is no resistance in the system. When the pump perormance is adjusted with this method, the pump will deliver a higher head than necessary or that particular system.
Resulting characteristic Smaller pump System
Hv
Throttle valve
Hs
Q1
Q2
Q
Q3
Fig.: 4.1.2: The throttle valve increases the resistance in the system, consequently reducing the low.
I the pump and the throttle valve are replaced by a smaller pump, the pump will be able to meet the desired low Q 1 at a lower pump head, resulting in less power consumption, see fgure 4.1.2. Bypass valve
4.1.2 Bypass control Compared to the throttle valve, installing a bypass valve will result in a certain minimum low, Q BP, in the pump independent o the system characteristics, see igure 4.1.3. The low, QP, is the sum o the low in the system, QS, and the low in the bypass valve, QBP..
QBP QP
QS
System
HP
H Bypass valve
Hmax Smaller pump
The bypass valve will introduce a maximum limit o head to the system, H max , see igure 4.1.3. Even when the required low in the system is zero, the pump will never run against a closed valve. Like the throttling valve method, the required low, Q S, can be met by a smaller pump and no bypass valve, resulting in a lower low and less energy consumption.
System
Qs
QBP Resulting characteristic
HP Pump
QBP
QS
QP
Q
Fig.: 4.1.3: The bypass valve diverts part o the low rom the pump, reducing the low in the system
Section 4.1 Adjusting pump perormance
4.1.3 Modiying impeller diameter Another way to adjust the perormance o a centriugal centriu gal pump is to modiy the impeller diameter, reducing the diameter which, consequently, reduces pump perormance. Compared to the throttling and bypass methods, which can be carried out during operation, the impeller trimming has to be done in advance beore the pump is installed or in connection with service; it cannot be done while the pump is in operation. The ollowing ormula shows the relationship between the impeller diameter and the pump perormance:
Note that the ormulas are an expression o an ideal pump. In practice, the pump eiciency decreases when the impeller diameter is reduced. For minor changes o the impeller diameter, D x > 0.8 . Dn, the eiciency is only reduced by a ew percentage points. The degree o eiciency reduction depends on pump type and duty point.
D
H
Hn Hx
Dn Dx
As it appears rom the ormulas, the low and the head change with the same ratio: that is, the ratio change o the impeller diameter to the second power. The duty points ollowing the ormulas are placed on a straight line starting in (0,0). The change in power consumption is ollowing the diameter change to the ourth power.
4.1.4 Speed control The last method o controlling the pump perormance to be covered in this section is the variable speed control method. Speed control by means o a requency converter is the most eicient way o adjusting pump perormance exposed to variable low requirements.
Qx
Qn
Q
Fig. 4.1.4: Change in pump perormance perormance when the impeller diameter is reduced
The ollowing equation applies with close approximation to how the change in speed o a centriugal pump inluences the perormance o the pump:
The ainity laws apply when the system characteristic remains unchanged or nn and nx and orms a parabola through (0,0) – see section section 3.1.2 (p 99). The power equation implies that the pump eiciency is unchanged at the two speeds. The ormulas in igure 4.1.5 show that the pump low (Q) is proportional to the pump speed (n). The head (H) is proportional to the second power o the speed (n) whereas the power (P) is proportional to the third power o the speed. In practice, a reduction o the speed will result in a slight all in eiciency. The eiciency at reduced speed (n x) can be estimated by the ollowing ormula, which is valid or speed reduction down to 50% o the maximum speed:
I the need or precise power saved is desired, requency converter and motor eiciencies must be taken into account.
Fig. 4.1.5: Pump parameters or dierent ainity ainity equations
Section 4.1 Adjusting pump perormance
4.1.5 Comparison o adjustment methods When the pump and its perormance-changing device is considered as one unit, the resulting QHcharacteristic o this device can be compared to dierent systems.
Throttle control The throttling method implies a valve connected in series with a pump, see s ee igure 4.1.6a. This connection acts as a new pump at unchanged maximum head but reduced low perormance. For an illustration o the pump curve, Hn, the valve curve, and the curve or the complete system, - H x, see igure 4.1.6b.
Bypass control When connecting a valve across the pump, the connection acts as a new pump at reduced maximum head and a QH curve with a changed characteristic, see igure 4.1.7a. The curve will be more linear than quadratic, see igure 4.1.7b.
a
b Throttle valve
Hn
Valve
Fig. 4.1.6: Throttle valve connected connected in series with a pump
a
b Bypass valve
Modiying impeller diameter This method does not imply extra components. Figure 4.1.8 shows the reduced QH curve (Hx) and the original curve characteristics (Hn).
Hx
Hn
Hx
Valve
Fig. 4.1.7: Bypass valve connected connected across the pump
Speed control The speed control method results in a new QH curve at reducedheadandlow,seeigure1.4.9.The characteristics o the curves remain the same. However, when speed is reduced the curves become more lat as the head is reduced to a higher degree than the low. In comparison, the speed control method also makes it possible to extend the perormance range o the pump above the nominal QH curve by increasing the speed above nominal speed level o the pump; see the H y curve in igure 4.1.9. I this over-synchronous operation is used, the size o the motor has to be taken into account.
D
Hn
Hx
Hn
Hx
Fig. 4.1.8: Impeller diameter adjustment
Speed controller
Fig. 4.1.9: Speed controller controller connected to a pump
H y
4.1.6 Overall efficiency of the pump system Both the throttling and the bypass method introduce some hydraulic power losses in the valves (P loss = k Q H), thereore reducing eiciency o the pumping system. Reducing the impeller size in the range o Dx/Dn>0.8 does not have a signiicant impact on pump eiciency and does not have a negative inluence on the overall eiciency o the system. The eiciency o speed-controlled pumps is only aected to a limited extent i the speed reduction does not drop below 50% o the nominal speed. The eiciency is only reduced by a ew percentage-points, and it does not have an impact on the overall running economy o speed-controlled solutions, see igure 1.4.16 in section 1.4.5.
4.1.7 Example: Relative power consumption when the flow is reduced by 20 % In a given installation the low has to be reduced rom Q = 260 GPM to 220 GPM. In the original starting point (Q = 260 GPM and H = 230 t) the power input to the pump is set relatively to 100%. Depending on the method o perormance adjustment, the power consumption reduction will vary. This is urther discussed on the ollowing pages.
Section 4.1 Adjusting pump perormance
Throttle control The power consumption is reduced to about 94% when the low drops rom 264 to 220 GPM. The throttling results in an increased head, see igure 4.1.10. The maximum power consumption or some pumps is at a lower low than the maximum low. I this is the case, the power consumption increases because o the throttle.
= Modiied duty point = Original duty point
H [ft]
249 229 180
Q
P2 100% 94%
220
Bypass control To reduce the low in the system, the valve has to reduce the head o the pump to 180 t. This can only be done by increasing the low in the pump. As it appears rom igure 4.1.11, the low is consequently increased to 356 GPM, which results in an increased power consumption o up to 10% above original consumption. The degree o increase depends on the pump type and the duty point. Thereore, in some cases, the increase in P 2 is equal to zero and in rare cases, P2 might decrease slightly.
Modiying impeller diameter
H [ft]
= Modiied duty point = Original duty point 229 180
When the speed o the pump is controlled, both the low and the head are reduced, see igure 4.1.13. Consequently, the power consumption has reduced to around 65% o the original consumption.
Q
P2 110% 100%
220
264
356
Q [GPM]
Fig. 4.1.11: Relative power power consumption - bypass control H [ft]
When the impeller diameter is reduced, both the low and the head o the pump drop. By a low reduction o 20%, the power consumption is reduced to around 67% o its original consumption, see igure 4.1.12.
Speed control
Q [GPM]
264
Fig. 4.1.10: Relative power consumption consumption - throttle control control
= Modiied duty point = Original duty point 229 180
Q
P2 100% 67%
220
264
Q [GPM]
Fig. 4.1.12: Relative power consumption - modiying modiying impeller diameter H [ft]
To obtain the best possible eiciency, the impeller diameter adjustment method or the speed-controlled method o the pump are the best options or reducing the low in the installation. When the pump has to operate in a ixed, modiied duty point, the impeller diameter adjustment method is the best solution. However, in installations where the low demand varies, the speed-controlled pump is the best solution.
= Modiied duty point = Original duty point 70 55
Q Q
P2 100% 65%
50
60
Q [GPM]
Fig. 4.1.13: Relative power power consumption - speed control
Summary Figure 4.1.14 gives an overview o the dierent adjustment methods that are presented in the previous section. Each method has its pros and cons which should be considered when choosing an adjustment method or a system.
Continuous adjustment possible?
Method
Throttle control
Yes
The resulting performance curve will have
Reduced Q
Overall efficiency of the pump system
Relative power consumption by 20% reduction in flow
Considerably reduced
94%
Considerably reduced
110%
Slightly reduced
67%
Slightly reduced
65%
Throttle valve Hn Hx Valve
Bypass control
Yes
Reduced H and changed curve
Bypass valve
Hn Hx Valve
Modifying impeller diameter
No
Reduced Q and H
D Hn Hx
Speed control
Yes
Reduced Q and H
Speed controller
Hn Hx H y
Fig. 4.1.14: Characteristics Characteristics o adjustment methods.
Section 4.2 Speed-controlled Speed-controll ed pump solutions
As discussed in the previous section, speed control o pumps is an eicient way o adjusting pump perormance to the system. In this section the possibilities o combining speed-controlled pumps with PI-controllers and sensors measuring system parameters, such as pressure, dierential pressure and temperature, are discussed. The dierent options will be presented by examples.
Setpoint p set
PIcontroller
Break tank
Actual value p 1 Pressure transmitter
Speed controller
PT h Taps
p1
Q1 H1
H
4.2.1 Constant pressure control A pump has to supply tap water rom a break tank to dierent taps in a building. The demand or tap water is varying, so the system characteristic varies according to the required low. Due to comort and energy savings, a constant supply pressure is recommended. As it appears rom igure 4.2.1, the solution is a speed-controlled pump with a PI-controller. The PI-controller compares the needed pressure, pset, with the actual supply pressure, p 1, measured by a pressure transmitter, PT. I the actual pressure is higher than the setpoint, the PI-controller reduces the speed and, consequently, the perormance o the pump until p 1 is equal to pset. Figure 4.2.1 shows what happens when the low is reduced rom Q max to Q 1 . The controller reduces the speed o the pump rom nn to nx to ensure that the required discharge pressure is p1 = pset. The pump installation ensures that the supply pressure is constant in the low range o 0 to Qmax. The supply pressure is independent o the level, (h), in the break tank. I h changes, the PIcontroller adjusts the speed o the pump so that p 1 always corresponds to the setpoint.
nn nx pset
h
Q1
Qmax
Q
Fig. 4.2.1: Water supply system with speed-controlled pump delivering constant pressure to the system
4.2.2 Constant temperature control Perormance adjustment through speed control is suitable or a number o industrial applications. Figure 4.2.2 shows a system with a water-cooled injection molding machine or high quality production. The machine is cooled with water at 59 oF rom a cooling plant. To ensure that the molding machine runs properly and is cooled suiciently, the return pipe temperature has to be kept at a constant level; tr = 68oF. The solution is a speed-controlled pump controlled by a PI-controller. The PI-controller compares the needed temperature, t set, with the actual return pipe temperature, t r, which is measured by a temperature transmitter, TT. This system has a ixed system characteristic, and, thereore, the duty point o the pump is located on the curve between Qmin and Qmax. The higher the heat loss in the machine, the higher the low o cooling water is needed to ensure that the return pipe temperature is kept at a constant level o 68 oF.
Fig. 4.2.2: System with injection injection molding machine and temperature- controlled circulator pump ensuring a constant return pipe temperature
4.2.3 Constant dierential pressure in a circulating system Circulating systems, typically closed systems, are well suited or speed-controlled pumps, see Chapter 3. A dierential pressure controlled circulator pump is recommended or circulating systems with variable system characteristic, see igure 4.2.3. This igure shows a heating system with a heat exchanger where the circulated water is heated up and delivered to three consumers, such as radiators, by a speed-controlled pump. A control valve is connected in series at each consumer to control the low according to the heat requirement. The pump is controlled according to a constant dierential pressure measured across the pump. As depicted by the horizontal line in igure 4.2.3, the pump system oers constant dierential pressure in the Q-range o 0 to Qmax.
Fig. 4.2.3: Heating system with speed-controlled speed-controlled circulator pump delivering constant dierential pressure to the system
Section 4.2 Speed-controlled Speed-controll ed pump solutions
4.2.4 Flow-compensated dierential pressure control
Setpoint Hset
The main unction o the pumping system in igure 4.2.4 is to maintain a constant dierential pressure across the control valves at the consumers, such as radiators. In order to do so, the pump must overcome riction losses in pipes, heat exchangers, ittings, etc.
PIcontroller
Actual value H 1
Speed controller Q1
DPT1 DPT2
As discussed in Chapter 3, the pressure loss in a system is proportional to the low in second power. The best way to control a circulator pump in a system like the one shown in the igure at right is to allow the pump to deliver a pressure that increases when the low increases.
H
nn nx
When the demand o low is low, the pressure losses in the pipes, heat exchangers, ittings, etc. are low as well, and the pump supplies only a pressure equivalent to what the control valve requires, H setH . When low demand increases, pressure losses increase to the second power, and the pump has to increase the delivered pressure, depicted as the blue curve in igure 4.2.4.
Hset Hf
H1
Q1
Qmax
Q
Fig. 4.2.4: Heating system with speed-controlled peed-controlled circulator pump delivering low-compensated dierential pressure to the system
Such a pumping system can be designed as ollows:
• The dierential pressure transmitter is placed across the pump and the system is running with low-compensated dierential pressure control – DPT1, see igure 4.2.4.
pump curve data has to be stored in the controller. This data is used to calculate the low as well as how much the setpoint H set must be reduced at a given low to ensure that the pump perormance meets the required blue curve in igure 4.2.4.
• The dierential pressure transmitter is placed close to the consumers and the system is running with dierential pressure control – DPT 2, see ig. 4.2.4. The irst solution places the pump, PI-controller, speed control and the transmitter close to one another providing easy installation and making it possible to get the entire system as one single unit, see section 4.4. To get the system up and running,
The second solution requires more installation costs because the transmitter has to be installed at the installation site, and the necessary cabling has to be added. Both systems are equal in perormance. The transmitter measures the dierential pressure at the consumer and compensates automatically or the increase in required pressure in order to overcome the increase in pressure losses in the supply pipes, etc.
Section 4.3 Advantages o speed control
A large number o pump applications do not require ull pump perormance 24 hours a day. Thereore, it is an advantage to be able to adjust the pump’s perormance in the system automatically. As seen in section 4.1, the best possible way o adapting the perormance o a centriugal pump is by means o speed control o the pump. Speed control o pumps is normally made by a requency converter unit.
Reduced energy consumptio consumption n Speed-controlled pumps use only the amount o energy needed to address a speciic pump installation. Compared to other control methods, requencycontrolled speed control oers the highest eiciency and the most eicient utilization o the energy, see section 4.1.
Low lie cycle costs On the ollowing pages, speed-controlled pumps in closed and open systems will be examined. The advantages that speed control provides and the beneits that speed-controlled pumps with requency converters oer are presented irst.
As we will see in Chapter 5, the energy consumption o a pump is a very important actor when calculating a pump’s lie cycle costs. Thereore, it is important to keep the operating costs o a pumping system at the lowest possible level. Eicient operation leads to lower energy consumption and results in lower operating costs. Compared to ixed-speed pumps, it is possible to reduce the energy consumption by up to 50% with a speed-controlled pump.
Environment protection Energy-eicient pumps cause less pollution and harm to the environment.
Increased comort Speed control in dierent pumping systems provides increased comort in water supply systems, automatic pressure control, and where the sot-start o pumps reduce water hammer and noise generated by too high pressure in the system. In circulating systems, speed-controlled pumps ensure that the dierential pressure is kept at a level so that noise in the system is minimized.
Reduced system costs Speed-controlled pumps can reduce the need or commissioning and control valves in the system, thus reducing the total system costs.
Section 4.4 Advantages o pumps with integrated requency converter
In many applications, pumps with integrated requency converters are the optimum solution. These pumps combine the beneits o a speed-controlled pump solution with the beneits gained rom combining a pump, a requency converter, a PI-controller and sometimes a sensor/pressure transmitter in one single unit, see igure 4.4.1. A pump with an integrated requency converter is not just a pump, it is a system that can solve application problems or save energy in a variety o pump installations. Pumps with integrated requency converters are ideal because they can be used instead o xed-speed pumps in replacement installations at no extra installation cost. The only requirement is a power supply connection and a itting o the pump with an integrated requency converter in the pipe system, and then the pump is ready or operation. Ater adjusting the required setpoint pressure, the system is operational. What ollows is a brie br ie description o the advantages that pumps with integrated requency converter have to oer.
Setpoint
PIcontroller Frequency converter
M
PT
Easy to install Pumps with integrated requency converters are just as easy to install as ixed-speed pumps. The motor is connected to the electrical power supply, and the pump is in operation. The manuacturer has made all internal connections and adjustments.
Optimal energy savings Because the pump, the motor and the requency converter are designed or compatibility, operation o the pump system reduces power consumption.
One supplier One supplier can provide the pump, requency converter and sensor which naturally acilitate the sizing, selection, and ordering procedures, as well as maintenance and service procedures.
Fig. 4.4.1: Pump unit with integrated requency converter and pressure transmitter
Wide perormance range Pumps with integrated requency converters have a broad perormance range which enables eicient perormance under widely varied conditions and meets a wide range o requirements. Fewer pumps can replace many ixed speed pump types with narrow perormance capabilities.
perormance curve and the system characteristic o a closed and an open system.
H [ft] 100% 320 280 90% 240
4.4.1. Perormance curves o speedcontrolled pumps
80%
200 70%
160
60%
120
50%
80
The ollowing is a discussion o how a speed-controlled pump’s perormance curve is read.
40
25%
0 0
20
40
60
80
100
120
140 Q [GPM]
P [hp]
1
Figure 4.4.2 provides an example o the perormance curves o a speed-controlled s peed-controlled pump. The rst curve shows the fow-head (QH) curve, and the second curve shows the corresponding power consumption curve.
10 8 6 4 2 0 Q [GPM]
Fig 4.4.2: Perormance curve or a speed-controlled pump
The perormance curves are plotted or every 10% decrease in speed rom 100% down to 50%. Likewise, the minimum curve represented by 25% o the maximum speed is also shown. As indicated in the diagram, you can select a speciic duty point, QH, and nd out at which speed the duty point can be reached and what the power consumption, P 1, is.
4.4.2 Speed-controlled pumps in dierent systems Speed-controlled pumps are used in a wide range o systems. The change in pump perormance and, consequently, the potential energy savings depend on the system in question. question . As discussed in Chapter 3, the characteristic o a system is an indication o the required head a pump has to deliver to transport a certain quantity o liquid through the system. Figure 4.4.3 shows the
H
H
Pump curve
Pump curve
System characteristic
Closed system
Q
HO
System characteristic
Open system
Fig 4.4.3: System characteristic point o a closed and an open system
Q
Section 4.4 Advantages o pumps with integrated requency converter
Speed-controlled pumps in closed systems In closed systems, like heating and air-conditioning, the pump has to overcome the riction losses in the pipes, valves, heat exchangers, etc. In this section, an example o a speed-controlled pump in a closed system will be presented. The total riction loss by a ull low o 66 GPM is 39.3 t, see igure 4.4.4.
The system characteristic starts in the point (0,0), shown by the red line in igure 4.4.5. Control valves in the system always need a certain operating pressure, so the pump cannot work according to the system characteristic. That is why some speedcontrolled pumps oer the proportional pressure control unction, which ensures that the pump will operate according to the orange line shown in the igure. As you can tell rom igure 4.4.5, the minimum perormance is around 57% o the ull speed. In a circulating system, operating at the minimum curve (25% o the ull speed) can be relevant in some situations, such as night-time duty in heating systems.
Q = 66 GPM
Boiler or like
H
Consumers Fig. 4.4.4: Closed system
H [ft] 100% 99%
320
280 90% 240
80%
200 70%
160
60%
120
50%
80 40
25%
0 0
20
40
60
80
100
120
140 Q [GPM]
P [hp]
1
10 8 6 4 2 0 Q [GPM]
Fig. 4.4.5: A speed-controlled pump in a closed system
Speed-controlled pumps in open systems The system characteristic as well as the operating range o the pump depend on the type o system in question. Figure 4.4.6 shows a pump in a pressure boosting / water supply system. The pump has to supply Q = 29 GPM to the tap which is placed h = 65 t above the pump. The inlet pressure to the pump, p s, is 14.5 psi, the pressure at the tap, p t, has to be 29 psi and the total riction loss in the system by ull low, p , is 18.8 psi.
he = 65.6 t SG p = 18.8 psi ps = 14.5 psi Q = 29 GPM
Figure 4.4.7 shows the QH curve o a pump which meets the requirements described. The required r equired head can be calculated by using the equation at right.
H pt ps p Q h
For maximum head at a low, Q, o 29 GPM, the equation to use ollows:
H = He +
2.31 (pt)
SG
—
2.31 (ps)
SG
+
pt = 29 psi
Fig. 4.4.6: Pump in a water supply system
-
Pressure at tapping tapping point point Suction pressure Friction loss Flow rate Static lit
2.31 (p )
SG
H = 65.6 + 2.31 (pt — ps + p )
pt - ps (2-1) . 105 H+ ρ. = 20 + = 99.08 t g 998 . 9.81
SG H = 65.6 + 2.31 (29 — 14.5 + 18.8) 1.0 H = 65.6 t + 76.9 t
H [ft] 100% 99%
200
175 90% 150
H = 142.5 t
80%
125 70%
HO
60%
75
To address this application rom zero to maximum low Q = 29 GPM, the pump operates in a relatively narrow speed band, rom about 65%-99% o the ull speed. In systems with less riction loss, the variation in speed will be even smaller. I there is no riction loss, the minimum speed in the above case is about 79% speed. As seen in the previous two examples, the possible variation in speed and power consumption is highest in closed systems. Thereore, the closed system accounts or the highest energy saving s aving potential.
50%
50 25
25%
0 0
5
10
15
20
25
30
35 Q [GPM]
P [hp]
1
2.5 2.0 1.5 1.0 0.5 0 Q [GPM]
Fig. 4.4.7: A speed-controlled pump in an open system
Section 4.5 Frequency converter
As mentioned, speed control o pumps involves a requency converter. This section will provide a closer look at requency converters, how they operate, and related precautions associated with using them.
4.5.11 Basic unction and characteristics 4.5. The speed o an asynchronous motor depends primarily on the pole number (2-pole, 4-pole, etc.) o the motor and the requency o the voltage supplied. The amplitude o the voltage supplied and the load on the motor shat also inluence the motor speed, however, not to the same degree. Changing the requency o the supply voltage is ideal or achieving asynchronous motor speed control. To ensure cor rect motor magnetization, it is also necessary to change the amplitude o the voltage.
T
2
1 > 2
1
n Fig. 4.5.1: Displacement o motor torque torque characteristic
Use o requency/voltage control results in a change in torque which, in turn, changes speed. Figure 4.5.1 shows the motor torque characteristic (T) as a unction o the speed (n) at two dierent requencies/voltages. The load characteristic o the pump is also shown. As it appears rom the igure, the speed is changed by changing requency/voltage o the motor. The requency converter changes requency and voltage, so it can be concluded that the task o a requency converter is to change the ixed supply voltage/requency; or example, 3x480v/60 Hz into a variable voltage/requency.
4.5.2. Components o the requency converter In principle, all requency converters consist o the same unctional blocks. The basic unction, as mentioned, is to convert the main electric supply into a new AC voltage with another requency and amplitude. The requency converter rectiies the incoming main electric supply and stores the energy in an intermediate circuit consisting o a capacitor. The DC voltage is then converted into a new AC voltage with another requency and amplitude. The rectiier can handle 50 Hz or 60 Hz requencies. Additionally, the incoming requency will not inluence the output requency, as this is deined by the voltage/requency pattern which is deined in the inverter. Using a requency converter in connection with asynchronous motors provides the ollowing beneits: • The system system can be used in both 50 and 60 cycleareas without modiications • The output output requency requency o the requency requency converter converter is independent o the incoming requency • The requency converter can supply output requencies higher than mains supply requency – making over synchronous operation possible As seen in igure 4.5.2, the requency converter consists o three other components: An EMC ilter, a control circuit and an inverter.
Mains supply AC EMC lter
Rectier
Intermediate circuit DC
Inverter
Control circuit
Fig. 4.5.2: Functional blocks o the requency converter
The EMC ilter This block is not part o the primary unction o the requency converter and, in principle, could be let out. However, in order to meet EMC requirements and local requirements, the ilter is necessary. The EMC ilter prevents high noise signals rom going back to the main electric supply and disturbing other electronic equipment connected to it. It also ensures that noise signals in the main electric supply generated by other equipment do not enter the electronic devices o the requency converter, and cause damage or disturbances.
The control circuit The control circuit block has two unctions. It controls the requency converter and provides communication between the product and the surroundings.
The inverter The output voltage rom a requency converter is not sinusoidal like the normal mains voltage. The voltage supplied to the motor consists o a number o squarewave pulses, see igure 4.5.3. The mean value o these pulses orms a sinusoidal voltage o the desired requency and amplitude. The switching requency can range rom a ew kHz up to 20 kHz, depending on the brand. To avoid noise in the motor windings, a requency converter with a switching requency above the range o audibility (~16 kHz) is preerable. This principle o inverter operation is called Pulse Width Modulation control (PWM), and it is the control principle most oten used in requency converters today. The motor current itsel is almost sinusoidal. This is shown in igure 4.5.4a, indicating motor current (top) and motor voltage. In igure 4.5.4b, a section o the motor voltage is shown, indicating how the pulse/pause ratio o the voltage changes.
Vmotor Mean value o voltage
t
T = 1/m Fig 4.5.3: AC voltage with variable requency (m) and variable voltage (Vmotor)
0 a
0
b *
* Detail
Fig 4.5.4: a) Motor current (top) and motor voltage at Pulse Width Modulation control. b) Section o motor voltage
Section 4.5 Frequency converter
4.5.3 Special conditions regarding requency converters There are some conditions which the installer and user should be aware o when installing and using requency converters or pumps with integrated requency converters. A requency converter will behave dierently than a standard asynchronous motor at the main electirc supply side.
a
b
Fig 4.5.5 a): Three-phase, twopole standard asynchronous motor
Non-sinusoidal power input, three-phase supplied requency converters This type o requency converter will not receive sinusoidal current rom the electrical supply. This inluences the dimensioning o the main elecrical cable, electric switch, etc. Figure 4.5.5 shows how the current and voltage appear or a: a) Three-phase, two-pole two-pole standard asynchronous asynchronous motor b) Three-phase, two-pole standard standard asynchronous motor with requency converter. In both cases the motor supplies 4.08 hp to the shat. A comparison o the current shows the ollowing dierences, see gure 4.5.6:
Fig 4.5.5 b): Three-phase, twopole standard asynchronous motor with requency converter
Sta tand nda ard mot otor or Mains voltage
460 V
Moto Mo torr wit with h re requ quen enccy converter 460 V
Mains current RMS
6.4 A
6.36 A
Mains current, peak
9.1 A
13.8 A
Power input, P1
3.68 KW
3.69 KW
cos ϕ, power actor (PF)
cosϕ = 0.83
PF = 0.86
Fig. 4.5.6: Comparison o current o a standard motor and a requency converter
• The current or the system with requency converter is not sinusoidal • The peak current is much higher (approx. 52%) or the requency converter option This is due to the design o the requency converter connecting the electric supply to a rectiier ollowed by a capacitor. The charging o the capacitor occurs during short time periods where the rectiied voltage is higher than the voltage in the capacitor at that moment. As mentioned, the non-sinusoidal current causes other conditions at the electric supply side o the motor. For a standard motor without a requency converter, the relation between voltage (V), current (I) and power (P) is shown in the ormula at right. The same ormula cannot be applied or calculating the power input or motors with requency converters.
V
PF
V
V
PF
(
(
PF
4.93 hp
Because these are not sinusoidal, there is no accurate way o calculating the power input based on simple current and voltage measurements. Instead, the power must be calculated by means o instruments and on the basis o instantaneous measurements o current and voltage. I the power (P) and the RMS value o current and voltage are known, the power actor (PF) can be calculated by the ormula at right. The power actor has no direct connection with the way in which current and voltage are displaced in time. When measuring the input current in connection with installation and service o a system with a requency converter, it is necessary to use an instrument that is capable o measuring “non-sinusoidal” currents. In general, current measuring instruments or requency converters must be able to measure “True RMS.”
Frequency converters and earth-leakage circuit breakers Earth-leakage circuit breakers (ELCB) are used as extra protection in electrical installations. I a requency converter is to be connected, the ELCB installed must be able to brake. I ailure occurs on the DC side o the requency converter, the ELCB must be able to brake. To ensure that the ELCB will brake in case o earth-leakage current, it must be labeled as shown in igures 4.5.7 and 4.5.8 Both types o earth-leakage circuit breakers are available on the market today.
Fig 4.5.7: Labelling o the ELCB forsingle-phasefrequencyconverters
Fig 4.5.8: Labelling o the ELCB or three-phase requency converters
Chapter 5. Lie cycle costs calculation
Section 5.1: Lie cycle costs equation 5.1.1 Initial cost, purchase price 5.1.2 Installation and commissioning costs 5.1.3 Energy costs 5.1.4 Operating costs 5.1.5 Environmental costs 5.1.6 Maintenance and repair costs 5.1.7 Downtime costs (loss o production) 5.1.8 Decommissioning or disposal costs
Section 5.2: Lie cycle costs calculation – an example
Energy costs 90%
Maintenance costs 2-5% Initial costs 5-8%
Section 5.1 Lie cycle costs equation
In this section the elements that make mak e up a pump’s lie cycle costs (LCC) as well as how to calculate LCC will be addressed. Finally, an example will be presented to demonstrate how the LCC ormula is applied. The lie cycle costs o a pump are an expression o how much it costs to purchase, install, operate, maintain and dispose o a pump during its lietime.
The Hydraulic Institute, Europump and the US Department o Energy have developed the Pump Lie Cycle Costs (LCC) guide, see fgure 5.1.1., This tool was designed to help companies minimize waste and maximize energy efciency in dierent systems including pumping systems. Lie cycle cost calculations aid in decision making associated with design o new or repair o existing installations.
Fig. 5.1.1: A guide to lie cycle costs analysis or pumping systems
Typical lie cycle costs
Initial costs
The lie cycle costs (LCC) consist o the ollowing:
Maintenance costs Energy costs
Cic Cin Ce Co Cenv Cm Cs Cd
Initial cost, purchase price Installation and commissioning costs Energy costs Operating costs including labor Environmental costs Maintenance and repair costs Downtime costs (loss o production) Decommissioning or disposal costs
In the ollowing paragraphs, each o these elements is described. As it appears rom fgure 5.1.2, energy costs, initial costs and maintenance costs are the most important.
Fig. 5.1.2: Typical lie cycle costs o a circulating system in the industry
LCC is calculated by the ollowing ormula: LCC = Cic + Cin + Ce + Co + Cm + Cs + Cenv + Cd
5.1.1 Initial cost, purchase price The initial cost (Cic) o a pump system includes all equipment and accessories necessary to operate the system, such as pumps, requency converters, control panels and transmitters, see igure 5.1.3.
Control panels
Pump
Initial costs
Oten, there is a trade-o between the initial cost and the energy and maintenance costs. For example, expensive components oten have a longer lietime or a lower energy consumption than inexpensive components.
5.1.2 Installation and commissioning costs
Frequency converter
Transmitter
Fig. 5.1.3: Equipment that makes up a pumping system
8000 7000 6000
The installation and commissioning costs (C in) include the ollowing:
5000 4000 3000
• • • •
Installation o the pumps Foundation Connection o electrical wiring and instrumentation instrumentation Installation, connection and set-up o transmitters and requency converters, etc • Commissioning evaluation at start-up As in the case or initial costs, it is important to consider the trade-o options. Pumps with integrated requency converters oten have components integrated in the product. This kind o pump oten has a higher initial cost but lower installation and commissioning costs.
2000 1000 0
Initial costs
System 1 5200
System 2 7300
Fig. 5.1.4: Initial costs o a constant speed pump system (System 1) and a controlled pump system (System 2)
Section 5.1 Lie cycle costs equation
5.1.3 Energy costs
Other use 80%
In most cases, energy consumption (C e) is the largest cost in the lie cycle costs o a pump system, where pumps oten run more than 2000 hours per year. In act, around 20% o the world’s electrical energy consumption is used or pump systems, see igure 5.1.5. Some o the actors inluencing the energy consumption o a pump system includes: • Load proile • Pump eiciency (calculation (calculation o the duty point, see igure 5.1.6) • Motor eiciency (the motor eiciency at partial partial load can vary signiicantly between high eiciency motors and normal eiciency motors) • Pump sizing (oten margins margins and round-ups tend tend to suggest oversized pumps) • Other system components, components, such as pipes and valves • Use o speed-controlled solutions. By using speedcontrolled pumps in the industry, it is possible to reduce the energy consumption by up to 50%
5.1.4 Operating costs including labor Operating costs (Co) cover labor costs related to the operation o a pumping system, and, in most cases, are modest. Today, dierent types o surveillance equipment allow connection o the pump system to a computer network, lowering operating costs.
5.1.5 Environmental costs The environmental costs (Cenv) include the disposal o parts and contamination rom the pumped liquid. This contribution to the lie cycle costs o a pumping system in the industry is modest.
Pump systems 20%
Fig. 5.1.5: Energy consumption worldwide
η
[%]
80
New Existing
60 40 20 0
0
22
44
66
88
110
132
154
176
198
220
242
Q [GPM]
Fig. 5.1.6: Eiciency Eiciency comparison o a new and an existing existing pump
5.1.6 Maintenance and repair costs Maintenance and repair costs (C m) relate to maintenance and repair o the pump system and include: Labor, spare parts, transportation and cleaning. Preventive maintenance will extend pump lie, optimize pump perormance and prevent pump breakdowns.
5.1.7 Downtime costs (loss o produc5.1.7 tion) Downtime costs (Cs) are extremely important to pump systems used in production processes. Production stoppage is costly, even or a short period o time. Though one pump may be enough or the application, it is a good idea to install a standby pump that can take over in the event o an unexpected ailure, see gure 5.1.7.
5.1.8 Decommissioning or disposal 5.1.8 costs Depending on the pump manuacturer, decommissioning or disposal costs (C d ) o a pump system varies. This cost is seldom taken into consideration when calculating LCC.
Calculating the lie cycle costs The lie cycle costs o a pump system are made up o the summation o the aorementioned components over the system’s lietime. Typically, the lietime range is 10 to 20 years. In the pump business, lie cycle costs are normally calculated by a simpliied ormula with ewer elements to consider. This ormula is shown at right.
Fig. 5.1.7: A standby pump assures that production continues in case o pump breakdown
Simplified: LCC = Cic + Ce + Cm Cic Initial costs, purchase price Ce
Energy costs
Cm
Maintenance and repair costs
Section 5.2 Lie cycle costs calculation – an example
The example using the LCC ormula mentioned on the previous page ollows: An industry needs a new water supply pump and two solutions are taken into consideration: • A ixed speed multistage centriugal centriugal pump • A variable speed multistage multistage centriugal pump According to the calculations, the variable speed pump consumes 40% less energy than the ixed speed pump. However, the initial cost, Cic, o the variable speed pump is twice that o the ixed speed pump. Lie cycle costs calculations will help determine which pump to install in the system. The application has the ollowing characteristics: • 12 operating hours hours per day • 220 operating days days per year • Lietime o 10 years (calculation period)
Pump types
Fixed speed
Variable speed
Average power consumption Operating hours per day Working days per year Calculation period
kw hours days years
18.76 12 220 10
11.31 12 220 10
Total energy consumption
kwh
495,264
298,584
Electrical power price Pump price Maintenance costs Energy costs
USD/kwh USD USD USD
.07 3602 1417 33,284
.07 7204 1417 20,066
Total costs
USD
38,303
28,688
45,000
D S U
40,000
Pump price
35,000 30,000
Energy costs
Maintenance costs
25,000 20,000 15,000 10,000 5,000 0
Fixed speed
Variable speed
Fig. 5.1.8: Lie cycle costs o a ixed and a variable speed pump
Based on this data, it is possible to calculate the lie cycle costs o the two solutions. Even though the initial cost o a variable speed pump is twice as high as a ixed speed pump, the total cost o the variable speed solution is 25% lower than the ixed speed pump solution ater 10 years. Besides the lower lie cycle costs the variable speed pump provides, as discussed in chapter 4, some operational beneits, such as constant pressure in the system.
45,000 40,000 35,000 30,000 D S U
25,000 20,000 15,000 Fixed speed Variable speed
10,000 5,000
The payback time o the variable speed pump solution is a bit longer because the pump is more expensive. As you can tell rom igure 5.1.9, the payback time is around 2½ years, and in general industrial applications, this is considered to be a good investment.
0 0
2
4
Years
6
8
Fig. 5.1.9: Payback time or a ixed and a variable speed pump
10
Appendix A) Notations and units B) Unit convers conversion ion tables C) SI-prefxes and Greek alphabet D) V Vapo aporr pressure apo pressu pre ssure re and specifc specif spe cifcc gra gravit gravity vityy o water water at dierent die di eren rentt temperatures temper tem peratu atures res E) Orifce F) Change in static pressure due to change in pipe diameter G) Nozzles H) Nomogram or head losses in bends, bends, valves, valves, etc. I) Periodical system J) Pump standards K) Viscosity or dierent dierent liquids as a unction o liquid temperature temperature
Appendix A
Notations and units The table below provides an overview o the most commonly used notations and units or pumps and pump systems.
U.S.
SI
unit
unit
ft GPM psi psi
gph ft
psi
ft
ft lb ft
lb gal
ft lb ft
in in ft
g = 32.174 ft/s m
ft RPM hp
745.7 w = 1 hp
Appendix B
Unit conversion tables The conversion tables or pressure and low show the most commonly used units or pumping systems
CONVERSION FACTORS - UNITS OF LENGTH Examples: 2 Yards x 3 = 6 Feet x 0.333 = 1 Yard Unit
Inch
Foot Yard Inch 1 0.0833 0.0278 Foot 12 1 0.333 Yard 36 3 1 Centim eters 0.3937 0.0328 0.0109 Meter 39.37 3.281 1.094 1 Mile = 5280 ft. = 1760 yards = 1609.3 meters = 1.61 Kilometers 1 Kilometer = 1000 meters = 1093.6 yards = .62137 miles
Centimeter 2.54 30.48 91.44 1 100
Meter 0.0254 0.3048 0.9144 0.01 1
CONVERSION FACTORS - UNITS OF FLOW Examples: 500 U.S. Gpm x .00144 = .72 U.S. Mgd. x 694.5 = 6945 U.S. Gpm Unit U.S. Gal./Min. Imp. Gal./Min. U.S. Mgd (2) Imperial Mgd (2) Cu. Ft./Sec. Cu. Meters/Hr. Liters /Sec. Barrels /Min. (3) Barrels /24 Hr s.(3) (1) US Mgd = Million (2) 42 gal. bbl.
U.S U. S. Imp Im p. U.S. U. S. Mgd Im Imp per eria iall Cu. Ft Ft.. Cu. Me Mete ters rs Li Lite ters rs Ba Barr rrel els s/M /Min in.. Bar arre rels ls/2 /24 4 Hrs rs.. Gpm Gpm Mgd (2) /Sec. /Hr. /Sec. (3) (3) (2) 1 0.833 0.00144 0.0012 0.00223 0.227 0.0631 0.0238 34.25 1.2 1 0.00173 0.00144 0.00268 0.272 0.0757 0.0286 41.09 694.4 578.7 1 0.833 1.547 157.73 43.8 16.53 23786.6 833.4 694.5 1 .2 1 1.856 189.28 52.56 19.83 28544 448.8 374 0.646 0.538 1 101.9 28.32 10.68 15360.4 4.403 3.67 0.00634 0.00528 0.00981 1 0.2778 0.1047 150.8 15.85 13.21 0.0228 0.019 0.0353 3.6 1 0.377 542.86 34.99 0.0605 0.0504 0.0937 9 .5 3 4 2.65 1 1440 42 0.0243 0.000042 0.000035 0.000065 0.00662 0.00184 0.000694 1 0.0292 U.S. gallons per 24 hr. day. Imp Mgd = Million Im peri al gallons per 24 hr. day.
CONVERSION FACTORS - UNITS OF PRESSURE Examples: 15 Ft. Water x .433 = 6.49 Psi 15 Psi x 2.31 = 34.65 Ft. Water In. W ater In. W ater Ft. W ater Psi. In. Hg. Mm. Hg. Bar atm Kilopascal
1 12 27.72 13.596 0.5353 401.86 407.19 4.0186
Ft. W ater 0.0833 1 2.31 1.133 0.0446 33.49 33.93 0.3349
Psi 0.0361 0.433 1 0.4906 0.0193 14.503 14.696 0.1451
In. Hg. 0.0736 0.883 2.04 1 0.03937 29.54 29.92 0.2954
Mm. Hg. 1.87 22.43 51.816 25.4 1 750.5 760 0.7505
Bar 2.538 30.45 70.31 34.49 1.357 1 1.0133 —
atm 0.0025 0.0304 0.0703 0.0345 0.0014 0.987 1 —
Appendix C
SI-prefxes and Greek alphabet Factor 109 106 103 102 10 10-1 10-2 10-3 10-6 10-9
1,000,000,000 1,000,000 1,000 100 10 0.1 0.01 0.001 0.000.001 0.000.000.001
Prefix
Symbol
giga mega kilo hekto deka deci centi milli mikro nano
G M k h da d c m
Greek alphabet Alfa
Α
α
Beta
Β
β
Gamma
Γ
γ
Delta
∆
δ
Epsilon
Ε
ε
Zeta
Ζ
ζ
Eta
Η
η
Theta
Θ
θ
Jota
Ι
ι
Kappa
Κ
κ
Lambda
Λ
λ
My
Μ
µ
Ny
Ν
ν
Ksi
ΚΣ
κσ
Omikron
Ο
ο
Pi
Π
π
Rho
Ρ
ρ
Sigma
Σ
σ
Tau
Τ
τ
Ypsilon
Υ
υ
Fi
Φ
φ
Khi
Χ
χ
Psi
Ψ
ψ
Omega
Ω
ω
µ
n
Appendix D
Vap apor or pressure pres pr essu sure re and and specifc spec sp ecif ifcc gravity grav gr avit ityy o water wat ater er at dierent dier di eren entt temperatures temp te mper erat atur ures es This table shows the specic gravity [sg], vapor pressure p [psi] and the density ρ [lb/t3] o water at dierent temperatures t [oF].
Properties of Water at Various Temperatures WATER TEMPERATURE 0
F
SPECIFIC GRAVITY
0
C
VAPOR PRESSURE
DENSITY
PSIA
FEET
lb/ft
3
32
0
1.002
0.0886
0.204
62.400
40
4.4
1.001
0.1217
0.281
62.425
45
7.2
1.001
0.1474
0.340
62.420
50
10.0
1.001
0.1780
0.411
62.410
55
12.8
1.000
0.2139
0.494
62.390
60
15.6
1.000
0.2561
0.591
62.370
65
18.3
.999
0.3056
0.706
62.340
70
21.1
.999
0.3629
0.839
62.310
75
23.9
.998
0.4296
0.994
62.270
80
26.7
.998
0.5068
1.172
62.220
85
29.4
.997
0.5958
1.379
62.170
90
32.2
.996
0.6981
1.617
62.120
95
35.0
.995
0.8153
1.890
62.060
100
37.8
.994
0.9492
2.203
62.000
110
43.3
.992
1.2750
2.965
61.980
120
48.9
.990
1.6927
3.943
61.710
130
54.4
.987
2.2230
5.196
61.560
140
60.0
.985
2.8892
6.766
61.380
150
65.6
.982
3.7184
8.735
61.190
160
71.1
.979
4.7414
11.172
60.990
170
76.7
.975
5.9926
14.178
60.790
180
82.2
.972
7.5110
17.825
60.570
190
87.8
.968
9.3400
22.257
60.340
200
93.3
.964
11.5260
2 7.584 27
60.110
210
98.9
.960
14.1230
3 3.983 33
59.860
212
100.0
.959
14.6960
35.353
59.810
220
104.4
.956
17.1860
41.343
59.610
230
110.0
.952
20.7790
50.420
59.350
240
115.6
.948
24.9680
60.770
59.080
250
121.1
.943
29.8250
73.060
58.800
260
126.7
.939
35.4300
87.050
58.520
270
132.2
.933
41.8560
103.630 10
58.220
280
137.8
.929
49.2000
122.180 12
57.920
290
143.3
.924
57.5500
143.875 14
57.600
Appendix E
Oriice Nipple oriices are typically used in boiler eed applications when boiler eed pumps need to discharge built-up pressure. These boiler eed pumps operate continuosly in order to provide on-demand hot water; but when no hot water is needed, the valve to the boiler is closed and the pump ends up operating under a harmul shut-o condition during extended periods o time in which there will be a rise in liquid temperature in the pump because the input horsepower being converted to heat in the pump is not dissipated. For that reason, in order to increase the run lie o the pump and control the temperature rise, the system is designed to allow the eed pump to discharge its build-up pressure through a bypass line in which a nipple oriice is installed. The oriice dissipates the high pressure and
allows water to low back to the reservoir tank. During eed pump system design, nipple oriices are sized using perormance charts, like the ones shown in the igure below, derived rom an acceptable mathematical approach that assumes a constant discharge coeicient (Cd) o 0.61 or all oriices in the the general equation equation Q = 2 19.636 Cd d H0.5, where Q is in gpm, d is the nipple oriice diameter in inches, and H is the dierential head in t. o water.
Orifice size
Approximate Discharge Through Bypass Nipple Orifice 1000 1/8"
3/16"
1/4"
5/16"
1/2"
1"
7/16"
7/8"
3/8"
13/16" 3/4" 11/16" 5/8" 9/16"
t e e F ( 100 d a e H
10 1
10
100
Flow (GPM)
1000
Appendix F
Change in static pressure due to change in pipe diameter As described in Chapter 2.2, a change in pipe dimension dimension results in a change in liquid velocity and consequently, consequently, a change in dynamic and static pressure. When head has to be determined (see page 86), the dierence in the two port dimensions requires a correction o the measured head.
Approximate Sudden Expansion Head Loss 100 d
D
10 ] t f [ H
1
0.1
10
100
1000
10000
Q[GPM]
d/ D=1/ 1.5
d/ D=1.25/ 2
d/ D=2/ 2.5
d/ D=2/ 3
d/ D=2.5/ 3
d/ D=2.5/ 4
d/ D=3/ 4
d/ D=4/ 5
d/ D=4/ 6
d/ D=5/ 6
d/ D=5/ 8
d/ D=6/ 8
d/ D=8/ 10
d/ D=8/ 12
d/ D=3/ 5 d/ D=10/ 12
d/ D=10/ 14
d/ D=12/ 14
d/ D=12/ 16
d/ D=14/ 16
d/ D=14/ 18
d/ D=16/ 18
d/ D=16/ 20
d/ D=18/ 20
Approximate Sudden Contraction Head Loss
100
D
d
10 ] t f [ H
1
0.1
10
100
1000 Q[GPM]
10000
Appendix G
Nozzles The relationship between the nozzle diameter d [inches], the needed low Q [GPM] and the required pressure beore the nozzle p [psi] is ound by the nomogram below. We assume that the nozzle has a quadratic behavior, and d / D is less than 1/3.
Q1 = Q2
p1 p2
Nozzle Diameter (inch)
n
( )
1/8
3/16
1/4
3/8
1/2
5/8
3/4
7/8
where n = 0.5. Some nozzles have a lower n value (check with the supplier). Pressure p [psi]
D
1/16
Nozzle diameter d [inch]
Flow Q [GPM]
1
1 1/8
1 1/4
1 3/8
1 1/2
1 3/4
2
2 1/4
2 1/2
2 3/4
3
3 1/2
4
4 1/2
5
5 1/2
6
Approximate discharge o a nozzle 400
I S P
100
10 5 0.1
1
10
100
Q [GPM]
1000
10000
100000
Appendix H
Friction Loss or Water in New Sch. 40 Steel Pipe at 60° F (Frict. loss in t. per 100 t. - Vel. in t. per sec.) gpm
1/8” (0 1/8” (0.2 .26 6 ID ID)) 1/4” 1/4” (0 (0.3 .36 6 ID ID)) Vel. Frict. Vel. Frict.
3/8” (0 3/8” (0.4 .49 9 ID ID)) Vel. Frict.
1/2” (0 1/2” (0.6 .622 ID ID)) Vel. Frict.
3/4” (0 3/4” (0.8 .822 ID ID)) Vel. Frict.
0.1
0.57
1.36
0.31
0.41
0.2
1.13
2.72
0.62
0.81
0.3
1.69
9.70
***
***
0.4
2.26
16.2
1.23
3.70
0.5
2.82
24.2
***
***
0.84
1.26
0.6
3.39
33.8
1.85
7.60
1.01
1.74
0.7
3.95
44.8
***
***
***
***
0.8
4.52
57.4
2.47
12.7
1.34
2.89
0.9
5.08
71.6
***
***
***
***
1.0
5.65
87.0
3.08
19.1
1.68
4.30
1.06
1.86
0.60
0.26
1.2
6.77
122
3.70
26.7
***
***
***
***
***
***
1.4
***
***
4.32
35.3
***
***
***
***
***
***
1.5
***
***
***
***
2.52
8.93
1.58
2.85
0.90
0.73
1.6
***
***
4.93
45.2
***
***
***
***
***
***
1.8
***
***
5.55
56.4
***
***
***
***
***
***
2.0
***
***
6.17
69.0
3.36
15.0
2.11
4.78
1.20
1.21
2.5
***
***
7.71
105
4.20
22.6
2.64
7.16
***
***
3.0
***
***
9.25
148
5.04
31.8
3.17
10.0
1.81
2.50
3.5
***
***
10.8
200
5.88
42.6
3.70
13.3
***
***
4.0
***
***
12.3
259
6.72
54.9
4.22
17.1
2.41
4.21
4.5
***
***
13.9
326
7.56
68.4
4.75
21.3
***
***
5.0
***
***
15.4
396
8.40
83.5
5.28
29.8
3.01
6.32
5.5
***
***
***
***
9.24
100
5.81
30.9
***
***
6.0
***
***
***
***
10.1
118
6.34
36.5
3.61
8.87
6.5
***
***
***
***
***
***
6.86
42.4
***
***
7.0
***
***
***
***
11.8
158
7.39
48.7
4.21
11.8
7.5
***
***
***
***
***
***
7.92
55.5
***
***
8.0
***
***
***
***
13.4
205
8.45
62.7
4.81
15.0
8.5
***
***
***
***
***
***
8.98
70.3
***
***
9.0
***
***
***
***
15.1
258
9.50
78.3
5.42
18.8
9.5
***
***
***
***
***
***
10.0
86.9
***
***
10.0
***
***
***
***
16.8
316
10.6
95.9
6.02
27.0
12
***
***
***
***
***
***
12.7
136
7.22
32.6
14
***
***
***
***
***
***
14.8
183
8.42
43.5
15
***
***
***
***
***
***
***
***
9.02
50.0
16
***
***
***
***
***
***
***
***
9.63
56.3
18
***
***
***
***
***
***
***
***
10.8
70.3
20
***
***
***
***
***
***
***
***
12.0
86.1
25
***
***
***
***
***
***
***
***
15.1
134
30
***
***
***
***
***
***
***
***
18.1
187
35
***
***
***
***
***
***
***
***
***
***
40
***
***
***
***
***
***
***
***
***
45
***
***
***
***
***
***
***
***
***
50
***
***
***
***
***
***
***
***
***
60
***
***
***
***
***
***
***
***
***
*** *** *** ***
1” (1 (1.0 .04 4 ID ID)) Vel. Frict.
gpm
0.37 *** *** *** *** *** 0.74 *** 1.11 *** 1.48 *** 1.86 *** 2.23 *** 2.60 *** 2.97 *** 3.34 *** 3.71 4.45 5.20 *** 5.94 6.68 7.42 9.27 11.1 13.0 14.8 16.7 18.6 22.3
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.2 1.4 1.5 1.6 1.8 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 12 14 15 16 18 20 25 30 35 40 45 50 60
0.11 *** *** *** *** *** 0.38 *** 0.78 *** 1.30 *** 1.93 *** 2.68 *** 3.56 *** 4.54 *** 5.65 *** 6.86 9.62 12.8 *** 16.5 20.6 25.1 38.7 54.6 73.3 95.0 119 146 209
Appendix H
Friction Loss or Water in New Sch. 40 Steel Pipe at 60° F (Frict. loss in t. per 100 t. - Vel. in t. per sec.) gpm
1 1/4” (1.38 ID) 1 1/2” (1.61 ID) Vel. Frict. Vel. Frict.
2” (2.07 ID) 2 1/2” (2.47 ID) Vel. Frict. Vel. Frict.
3” (3.07 ID) Vel. Frict.
4” (4.07 ID) Vel. Frict.
gpm
0.04 *** 0.07 *** 0.12 *** 0.18 0.25 0.33 0.42 0.52 0.61 0.86 1.16 1.49 1.89 2.27 2.70 3.19 3.72 4.28 4.89 6.55 8.47 10.5 13.0 15.7 18.6 21.7 25.3 28.9 32.8 37.0 41.4 46.0 50.9 61.4 72.0 97.6
5 10 12 14 16 18 20 25 30 35 40 45 50 60 70 80 90 100 120 140 160 180 200 220 240 260 280 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1100 1200 1400
5
1.07
0.52
0.79
0.25
0.48
0.07
10
2.15
1.77
1.58
0.83
0.96
0.25
0.67
0.10
0.43
0.04
12
2.57
2.48
1.89
1.16
1.15
0.35
0.80
0.15
***
***
14
3.00
3.28
2.21
1.53
1.34
0.46
0.94
0.20
***
***
16
3.43
4.20
2.52
1.96
1.53
0.59
1.07
0.25
***
***
18
3.86
5.25
2.84
2.42
1.72
0.73
1.21
0.31
***
***
20
4.29
6.34
3.15
2.94
1.91
0.87
1.34
0.36
0.87
0.13
25
5.37
9.66
3.94
4.50
***
***
***
***
***
***
***
30
6.44
13.6
4.73
6.26
2.87
1.82
2.01
0.75
1.30
0.27
0.76
35
7.52
18.5
5.52
8.38
3.35
2.42
2.35
1.00
***
***
***
40
8.58
23.5
6.30
10.8
3.82
3.10
2.68
1.28
1.82
0.55
1.01
45
9.66
29.5
7.10
13.5
4.30
3.82
3.02
1.57
***
***
***
50
10.7
36.0
7.88
16.4
4.78
4.67
3.35
1.94
2.17
0.66
1.26
60
12.9
51.0
9.46
23.2
5.74
6.59
4.02
2.72
2.60
0.92
1.51
70
15.0
68.8
11.0
31.3
6.69
8.86
4.69
3.63
***
***
1.76
80
17.2
89.2
12.6
40.5
7.65
11.4
5.36
4.66
3.47
1.57
2.02
90
19.3
112
14.2
51.0
8.60
14.2
6.03
5.82
***
***
2.27
100
21.5
138
15.8
62.2
9.56
17.4
6.70
7.11
4.34
2.39
2.52
120
25.7
197
18.9
88.3
11.5
24.7
8.04
10.0
5.21
3.37
3.02
140
30.0
267
22.1
119
13.4
33.2
9.38
13.5
6.08
4.51
3.53
160
***
***
25.2
158
15.3
43.0
10.7
17.4
6.94
5.81
4.03
180
***
***
28.4
199
17.2
54.1
12.1
21.9
7.81
7.28
4.54
200
***
***
31.5
241
19.1
66.3
13.4
26.7
8.68
8.90
5.04
220
***
***
***
***
21.0
80.0
14.7
32.2
9.55
10.7
5.54
240
***
***
***
***
22.9
95.0
16.1
38.1
10.4
12.6
6.05
260
***
***
***
***
24.9
111
17.4
44.5
11.3
14.7
6.55
280
***
***
***
***
26.8
128
18.8
51.3
12.2
16.9
7.06
300
***
***
***
***
28.7
146
20.1
58.5
13.0
19.2
7.56
350
***
***
***
***
***
***
23.5
79.2
15.2
26.3
8.82
400
***
***
***
***
***
***
26.8
103
17.4
33.9
10.1
450
***
***
***
***
***
***
30.2
132
19.6
43.0
11.3
500
***
***
***
***
***
***
33.5
160
21.7
52.5
12.6
550
***
***
***
***
***
***
***
***
23.9
63.8
13.9
600
***
***
***
***
***
***
***
***
26.0
75.7
15.1
650
***
***
***
***
***
***
***
***
28.2
88.6
16.4
700
***
***
***
***
***
***
***
***
30.4
101
17.6
750
***
***
***
***
***
***
***
***
***
***
18.9
800
***
***
***
***
***
***
***
***
34.7
131
20.2
850
***
***
***
***
***
***
***
***
***
***
900
***
***
***
***
***
***
***
***
***
***
21.4 22.7 23.9 25.2 27.7 30.2 35.3
950
***
***
***
***
***
***
***
***
***
***
1000
***
***
***
***
***
***
***
***
***
***
1100
***
***
***
***
***
***
***
***
***
***
1200
***
***
***
***
***
***
***
***
***
***
1400
***
***
***
***
***
***
***
***
***
***
0.50
Appendix H
Friction Loss or Water in New Sch. 40 Steel Pipe at 60° F (Frict. loss in t. per 100 t. - Vel. in t. per sec.) gpm
5” (5 (5.0 .055 ID ID)) Vel. Frict.
40
0.64
0.04
60
0.96
0.08
6” (6 (6.0 .077 ID ID)) 8” (7 (7.9 .98 8 ID ID)) 10” (1 10” (10 0.0 .022 ID ID)) 12” 12” (1 (11. 1.94 94 ID ID)) 14” (13 14” 13.1 .122 ID ID)) Vel. Frict. Vel. Frict. Vel. Frict. Vel. Frict. Vel. Frict.
80
1.28
0.14
100
1.60
0.21
1.11
0.09
120
1.92
0.29
1.33
0.12
140
2.25
0.39
1.55
0.16
160
2.57
0.48
1.78
0.20
180
2.89
0.60
2.00
0.25
1.15
0.07
200
3.21
0.73
2.22
0.30
1.28
0.08
220
3.53
0.87
2.44
0.36
1.41
0.10
240
3.85
1.03
2.66
0.41
1.54
0.11
260
4.17
1.19
2.89
0.48
1.67
0.13
280
4.49
1.37
3.11
0.54
1.80
0.15
300
4.81
1.58
3.33
0.62
1.92
0.17
1.22
0.06
350
5.61
2.11
3.89
0.85
2.24
0.22
1.42
0.07
400
6.41
2.72
4.44
1.09
2.57
0.28
1.63
0.09
450
7.22
3.41
5.00
1.36
2.89
0.34
1.83
0.12
500
8.02
4.16
5.55
1.66
3.21
0.42
2.03
0.14
1.43
550
8.81
4.94
6.11
1.97
3.53
0.50
2.24
0.17
1.58
600
9.62
5.88
6.66
2.33
3.85
0.59
2.44
0.20
1.72
700
11.2
7.93
7.77
3.13
4.49
0.79
2.85
0.25
2.01
800
12.8
10.2
8.88
4.04
5.13
1.01
3.25
0.33
2.29
900
14.4
12.9
9.99
5.08
5.77
1.27
3.66
0.41
2.58
1000
16.0
15.8
11.1
6.23
6.41
1.55
4.07
0.49
2.87
1100
***
***
12.2
7.49
7.05
1.86
4.48
0.59
3.15
1200
19.2
22.5
13.3
8.87
7.70
2.20
4.88
0.70
3.44
1300
***
***
14.4
10.4
8.34
2.56
5.29
0.81
3.73
1400
22.5
30.4
15.5
12.0
8.98
2.96
5.70
0.94
4.01
1500
***
***
16.7
13.7
9.62
3.38
6.10
1.07
4.30
1600
25.7
39.5
17.8
15.6
10.3
3.83
6.51
1.21
4.59
1700
***
***
18.9
17.5
10.9
4.29
6.92
1.38
4.87
1800
28.8
49.7
20.0
19.6
11.5
4.81
7.32
1.52
1900
***
***
21.1
21.8
12.2
5.31
7.73
1.68
2000
32.1
61.0
22.2
24.1
12.8
5.91
8.14
1.86
2500
***
***
27.7
37.2
16.0
8.90
10.2
2.86
3000
***
***
***
***
19.2
12.8
12.2
4.06
3500
***
***
***
***
22.4
17.5
14.2
5.46
4000
***
***
***
***
25.7
22.0
16.3
7.07
4500
***
***
***
***
***
***
18.3
8.91
5000
***
***
***
***
***
***
20.3
11.0
6000
***
***
***
***
***
***
24.4
15.9
7000
***
***
***
***
***
***
***
***
8000
***
***
***
***
***
***
***
***
9000
***
***
***
***
***
***
***
***
10000
***
***
***
***
***
***
***
***
5.16 5.45 5.73 7.17 8.60 10.0 11.5 12.9 14.3 17.2 20.1 22.9 *** ***
0.06 0.07 0.08 0.11 0.14 0.18 0.21 0.25 0.29 0.34 0.39 0.44 0.50 0.57 0.64 0.70 0.78 1.19 1.68 2.25 2.92 3.65 4.47 6.39 8.63 11.2 *** ***
1.90 2.14 2.37 2.61 2.85 3.08 3.32 3.56 3.80 4.03 4.27 4.51 4.74 5.93 7.12 8.30 9.49 10.7 11.9 14.2 16.6 19.0 21.4 23.7
0.09 0.11 0.13 0.16 0.18 0.21 0.24 0.28 0.31 0.35 0.39 0.43 0.48 0.73 1.04 1.40 1.81 2.27 2.79 4.00 5.37 6.98 8.79 10.8
gpm 40 60 80 100 120 140 160 180 200 220 240 260 280 300 350 400 450 500 550 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2500 3000 3500 4000 4500 5000 6000 7000 8000 9000 10000
Appendix H
Friction Loss or Water in New Sch. 40 Steel Pipe at 60° F (Frict. loss in t. per 100 t. - Vel. in t. per sec.) gpm 1000 1500 2000 2500 3000 3500 4000 4500 5000 6000 7000 8000 9000 10,000 12,000 14,000 16,000 18,000 20,000 25,000 30,000 35,000 40,000 50,000
16” (15.0 (15.00 0 ID) Vel. Frict. 1.82 2.72 3.63 4.54 5.45 6.35 7.26 8.17 9.08 10.9 12.7 14.5 16.3 18.2 21.8 25.4 29.0 *** *** *** *** *** *** ***
0.07 0.14 0.25 0.38 0.54 0.72 0.92 1.15 1.41 2.01 2.69 3.49 4.38 5.38 7.69 10.4 13.5 *** *** *** *** *** *** ***
16” (15.0 (15.00 0 ID) Vel. Frict.
2.87 3.59 4.30 5.02 5.74 6.45 7.17 8.61 10.0 11.5 12.9 14.3 17.2 20.1 22.9 25.8 28.7 *** *** *** *** ***
0.14 0.21 0.30 0.40 0.51 0.64 0.78 1.11 1.49 1.93 2.42 2.97 4.21 5.69 7.41 9.33 11.5 *** *** *** *** ***
20” (18.8 (18.81) 1) Vel. Frict.
2.31 2.89 3.46 4.04 4.62 5.19 5.77 6.92 8.08 9.23 10.4 11.5 13.8 16.2 18.5 20.8 23.1 28.9 34.6 *** *** ***
0.08 0.12 0.17 0.23 0.30 0.37 0.46 0.65
24” (22. (22.62 62 ID) Vel. Frict.
30” (29. (29.00 00 ID)* 36” (35. (35.00 00 ID)* Vel. Frict. Vel. Frict.
2.39
0.07
2.79
0.09
3.19
0.12
3.59
0.15
***
***
3.99
0.18
2.43
0.05
4.79
0.26
2.91
0.86
5.59
0.34
3.40
1.11
6.38
0.44
3.89
1.39
7.18
0.55
4.37
1.70
7.98
0.67
4.86
2.44
9.58
0.96
5.83
3.29
11.2
1.29
6.80
4.26
12.8
1.67
7.77
5.35
14.4
2.10
8.74
6.56
16.0
2.58
9.71
10.2
20.0
4.04
12.1
14.6
23.9
5.68
14.6
***
27.9
7.73
17.0
***
***
***
19.4
***
***
***
***
0.08 0.10 0.13 0.16 0.20 0.28 0.37 0.48 0.60 0.73 1.13 1.61 2.17 2.83 ***
1.94
0.03
1.58 1.89 2.21 2.52 2.84 3.15 3.78 4.41 5.04 5.67 6.30 7.88 9.46 11.0 12.6 15.8
0.02 0.03 0.04 0.04 0.06 0.07 0.09 0.13 0.16 0.20 0.25 0.38 0.54 0.72 0.94 1.45
gpm 1000 1500 2000 2500 3000 3500 4000 4500 5000 6000 7000 8000 9000 10,000 12,000 14,000 16,000 18,000 20,000 25,000 30,000 35,000 40,000 50,000
Note: 1. Table based on Darcy-Weisback Darcy-Weisback formula; formula; with no allowance for age, differences in diameter, diameter, or any other abnormal condition of interior surface. Any Factor of Safety must be estimated from the local conditions and the requirements of each particular installation. For general purposes, 15% is a reasonable Factor of Safety. 2. The friction friction loss data is based on seamless seamless Sch. 40 steel pipe. Cast iron iron (CI) pipe has a slightly larger larger ID than steel pipe in the 3” to 12” dia. range, which generally makes no practical difference with respect to water supply pumping problems. 3. Ductile Ductile Iron (DI) has a larger ID than both Sch. 40 steel and CI pipes for the same nominal diameter. diameter. Friction Losses in DI pipe can be approximated by multiplying the tabulated value by .75 in the 4” to 12” size range and .60 for 14” and larger sizes. 4. Velocity Velocity head values are not included included in the table, as they are normally not considered considered as a componen componentt of Total Head (TH) calculations to solve water supply pumping problem. Velocity and Velocity head can be calculated using the following formulas: Vel. (fps) = gpm (.410)/(ID) 2 = gpm (.321)/Area (in. 2); where: Area (in 2) = Vel. Head (ft.) = (Vel.) 2 /2g = (Vel.) 2/64.4
π
(ID) 2/4
5. Velocity within column (vertical drop/riser pipe) should be kept within the range of 4 - 15 fps (5.0 fps is optimum). Velocity within horizontal distribution piping should be kept within the range of 1 - 6 fps (3.0 fps is optimum). 6. Tabulated Tabulated friction loss values values are calculated based on water at 60°F and a kinematic viscosity viscosity = 0.00001217 ft /sec. (31.2 SSU). Correct tabulated values for fluid temperatures other than 60°F as following: Temp (°F) Correction factor
32 1.20
40 1.10
50 1.00
60 1.00
80 1.00
100 .95
150 .90
200 .85
212 .80
* The ID value specified for 30” and 36” sizes are for Sch. 20 pipe. Sch. 40 pipe is not available in diameters greater than 24”
Appendix H
Friction Loss or Water in New Type L. Copper Tubing and Sch. 40 PVC Pipe (Frict. loss in t. per 100 t. - Vel. in t. per sec.) 1/2” gpm
Tubing .545” ID Vel. Frict.
Pipe .622” ID Vel. Frict.
3/4” gpm
Tubing .785” ID Vel. Frict.
Pipe .824” ID Vel. Frict.
0.5 1.0 1.5
0.69 1.38 2.06
0.75 2.45 4.93
0.52 1.04 1.57
0.40 1.28 2.58
1 2 3
0.66 1.33 1.99
0.44 1.44 2.91
0.60 1.21 1.81
0.35 1.16 2.34
2.0 2.5 3.0
2.75 3.44 4.12
8.11 11.98 16.48
2.09 2.61 3.13
4.24 6.25 8.59
4 5 6
2.65 3.31 3.98
4.81 7.11 9.80
2.42 3.02 3.62
3.86 5.71 7.86
3.5 4.0 4.5
4.81 5.50 6.19
21.61 27.33 33.65
3.66 4.18 4.70
11.25 14.22 17.50
7 8 9
4.64 5.30 5.96
12.86 16.28 20.06
4.23 4.83 5.44
10.32 13.07 16.10
5.0 6.0 7.0
6.87 8.25 9.62
40.52 56.02 73.69
5.22 6.26 7.31
21.07 29.09 38.23
10 11 12
6.92 7.29 7.95
24.19 28.66 33.47
6.04 6.64 7.25
19.41 22.99 26.84
8.0 9.0 10.0
11.0 12.4 13.8
93.50 115.4 139.4
8.35 9.40 10.4
48.47 59.79 72.16
13 14 15
8.61 9.27 9.94
38.61 44.07 49.86
7.85 8.45 9.05
30.96 35.33 39.97
12.6 14.7
115.6 157.4
16 17 18
10.60 11.25 11.92
55.97 62.39 69.13
9.65 10.25 10.85
44.86 50.00 55.40
12.0 14.0 16.0 1” gpm
Tubing 1.03” ID Vel. Frict.
Pipe 1.05” ID Vel. Frict.
1 1/4” gpm
Tubing 1.27” ID Vel. Frict.
Pipe 1.38” ID Vel. Frict.
2 3 4
0.78 1.17 1.56
0.41 0.82 1.35
0.72 1.08 1.45
0.35 0.70 1.14
5 6 7
1.28 1.53 1.79
0.74 1.01 1.32
1.09 1.31 1.53
0.51 0.70 0.91
5 6 7
1.95 2.34 2.72
2.00 2.75 3.60
1.81 2.17 2.53
1.69 2.32 3.04
8 9 10
2.04 2.30 2.55
1.67 2.06 2.48
1.75 1.96 2.18
1.15 1.42 1.71
8 9 10
3.11 3.50 3.89
4.56 5.61 6.76
2.89 3.25 3.61
3.85 4.74 5.71
12 15 20
3.06 3.83 5.10
3.42 5.07 8.46
2.62 3.27 4.36
2.35 3.49 5.81
12 14 16
4.67 5.45 6.22
9.33 12.27 15.56
4.34 5.05 5.78
7.88 10.36 13.13
25 30 35
6.38 7.65 8.94
12.59 17.44 23.00
5.46 6.55 7.65
8.65 11.98 15.79
18 20 25
7.00 7.78 9.74
19.20 23.18 34.56
6.50 7.22 9.03
16.20 19.55 29.15
40 45 50
10.2 11.5 12.8
29.24 36.15 43.71
8.74 9.83 10.9
20.06 24.80 29.98
30 35 40
11.68 13.61 15.55
47.96 63.31 80.58
10.84 12.65 14.45
40.43 53.37 67.90
60 70 80
15.3 17.9 20.4
60.78 80.38 102.5
13.1 15.3 17.5
41.66 55.07 70.16
Appendix H
Friction Loss or Water in New Type L. Copper Tubing and Sch. 40 PVC Pipe (Frict. loss in t. per 100 t. - Vel. in t. per sec.) 1 1/2” gpm
Tubing 1.51” ID Vel. Frict.
Pipe 1.61” ID Vel. Frict.
2” gpm
Tubing 1.98” ID Vel. Frict.
Pipe 2.07” ID Vel. Frict.
8 9 10
1.44 1.62 1.80
0.73 0.90 1.08
1.27 1.43 1.59
0.55 0.67 0.81
16 18 20
1.66 1.87 2.07
0.66 0.82 0.98
1.53 1.72 1.92
0.55 0.68 0.82
12 15 20
2.16 2.70 3.60
1.49 2.21 3.68
1.91 2.39 3.19
1.12 1.65 2.75
25 30 35
2.59 3.11 3.62
1.46 2.01 2.65
2.39 2.87 3.35
1.22 1.68 2.21
25 30 35
4.51 5.41 6.31
5.48 7.58 9.99
3.98 4.78 5.58
4.09 5.65 7.45
40 45 50
4.14 4.66 5.17
3.36 4.15 5.01
3.83 4.30 4.80
2.80 3.46 4.17
40 45 50
7.21 8.11 9.01
12.68 15.67 18.94
6.37 7.16 7.96
9.45 11.68 14.11
60 70 80
6.21 7.25 8.28
6.95 9.16 11.65
5.75 6.70 7.65
5.79 7.63 9.70
60 70 80
10.8 12.6 14.4
26.30 34.74 44.24
9.56 11.2 12.8
19.59 25.87 32.93
90 100 110
9.31 10.4 11.4
14.41 17.43 20.71
8.61 9.57 10.5
12.00 14.51 17.24
90 100 110
16.2 18.0 19.8
54.78 66.34 78.90
14.4 15.9 17.5
40.76 79.34 58.67
120 130 140
12.4 13.4 14.5
24.25 28.04 32.07
11.5 12.5 13.4
20.18 23.33 26.69
2 1/2” gpm
Tubing 2.46” ID Vel. Frict.
Pipe 2.47” ID Vel. Frict.
3” gpm
Tubing 2.95” ID Vel. Frict.
Pipe 3.07” ID Vel. Frict.
20 25 30
1.34 1.68 2.02
0.35 0.52 0.72
1.31 1.63 1.96
0.33 0.49 0.67
20 30 40
0.94 1.41 1.88
0.15 0.31 0.51
0.87 1.30 1.74
0.13 0.25 0.42
35 40 45
2.35 2.69 3.02
0.94 1.19 1.47
2.29 2.61 2.94
0.88 1.12 1.38
50 60 70
2.35 2.82 3.29
0.76 1.05 1.38
2.17 2.61 3.04
0.63 0.87 1.15
50 60 70
3.36 4.03 4.70
1.77 2.46 3.24
3.26 3.92 4.57
1.66 2.30 3.03
80 90 100
3.76 4.23 4.70
1.75 2.16 2.61
3.48 3.91 4.35
1.45 1.80 2.17
80 90 100
5.37 6.04 6.71
4.12 5.08 6.15
5.22 5.88 6.53
3.85 4.75 5.74
110 120 130
5.17 5.64 6.11
3.10 3.63 4.19
4.79 5.21 5.65
2.57 3.01 3.47
110 120 130
7.38 8.05 8.73
7.30 8.54 9.87
7.19 7.84 8.49
6.82 7.92 9.22
140 150 160
6.58 7.05 7.52
4.79 5.42 6.09
6.09 6.52 6.95
3.97 4.50 5.05
140 150 160
9.40 10.1 10.8
11.28 12.78 14.36
9.14 9.79 10.45
10.54 11.94 13.42
170 180 190
7.99 8.46 8.93
6.80 7.54 8.32
7.39 7.82 8.25
5.64 6.25 6.89
170 180 190
11.4 12.1 12.8
16.03 17.79 19.62
11.1 11.8 12.4
14.98 16.61 18.33
200 220 240
9.40 10.3 11.3
9.13 10.85 12.70
8.70 9.56 10.40
7.56 8.99 10.52
200 220 240
13.4 14.8 16.1
21.54 25.61 30.01
13.1 14.4 15.7
20.12 23.93 28.03
260 280 300
12.2 13.2 14.1
14.69 16.81 19.06
11.3 12.2 13.0
12.17 13.93 15.79
Appendix H
Friction Loss or Water in New Type L. Copper Tubing and Sch. 40 PVC Pipe (Frict. loss in t. per 100 t. - Vel. in t. per sec.) 3 1/2” gpm
Tubing 3.43” ID Vel. Frict.
Pipe 3.55” ID Vel. Frict.
4” gpm
Tubing 3.91” ID Vel. Frict.
Pipe 4.63” ID Vel. Frict.
60 70 80
2.09 2.44 2.78
0.51 0.67 0.85
2.00 2.33 2.66
0.46 0.60 0.77
100 110 120
2.68 2.94 3.21
0.68 0.80 0.94
2.55 2.81 3.06
0.60 0.71 0.83
90 100 110
3.13 3.48 3.82
1.05 1.27 1.50
3.00 3.33 3.67
0.95 1.14 1.35
130 140 150
3.48 3.74 4.01
1.08 1.23 1.40
3.31 3.57 3.83
0.96 1.10 1.25
120 130 140
4.18 4.52 4.87
1.76 2.03 2.32
4.00 4.33 4.66
1.58 1.83 2.09
160 170 180
4.28 4.55 4.81
1.57 1.75 1.94
4.08 4.33 4.58
1.39 1.56 1.73
150 160 170
5.21 5.56 5.91
2.62 2.95 3.29
5.00 5.33 5.66
2.36 2.66 2.96
190 200 220
5.08 5.35 5.89
2.14 2.35 2.79
4.84 5.10 5.61
1.91 2.09 2.48
180 190 200
6.26 6.60 6.95
3.64 4.02 4.41
6.00 6.33 6.66
3.28 3.62 3.97
240 260 280
6.42 6.95 7.49
3.26 3.77 4.31
6.12 6.63 7.14
2.90 3.36 3.84
220 240 260
7.65 8.35 9.05
5.24 6.13 7.09
7.33 8.00 8.66
4.72 5.52 6.39
300 350 400
8.02 9.36 10.7
4.88 6.46 8.23
7.65 8.92 10.2
4.35 5.75 7.33
280 300 350
9.74 10.4 12.2
8.11 9.19 12.16
9.33 10.0 11.7
7.30 8.28 10.95
450 500 550
12.0 13.4 14.7
10.20 12.36 14.71
11.5 12.8 14.1
9.08 11.00 13.09
400 450 500
13.9 15.6 17.4
15.51 19.23 23.32
13.3 15.0 16.7
13.97 17.32 20.99
600 650 700
16.0 17.4 18.7
17.24 19.96 22.86
15.3 16.6 17.9
15.35 17.77 20.35
Note: 1. The friction friction losses listed under under the pipe pipe heading heading is approximatel approximatelyy valid for Regular Regular Weight Weight Copper Copper and Brass Pipe, in addition to Sch. 40 PVC Pipe 2. Table based based on Darcy - Weisback formula formula 3. No allowance allowance has been made for age, difference in diameter, diameter, or any abnormal condition of interior interior surface. Any factor of safety must be estimated from the local conditions and the requirements of each particular installation. installation . It is recommended that for most commercial design purposes a safety factor of 15 to 20% be added to the values in the tables.
Appendix H
Friction Losses Through Pipe Valves and Fittings (Straight Pipe in Feet - Equivalent Length)
SIZE OF PIPE (inches)
WIDE OPEN
GATE VALVE 1/4 1/2 CLOSED CLOSED
3/4 CLOSED
GLOBE VALVEWIDE OPEN
ANGLE VALVEWIDE OPEN
CHECK VALVEWIDE OPEN
ORDINARY ENTRANCE TO PIPE LINES
STD. 90° ELBOW
MEDIUM SWEEP 90° ELBOW
LONG SWEEP 90° ELBOW
1/8” 1/4” 3/8”
.14 .21 .27
.85 1.25 1.80
5.0 7.0 9.0
19 26 36
9 12 16
5 6 8
2.0 3.0 4.0
.46 .60 .75
.74 1.0 1.4
.65 .86 1.15
.50 .70 .90
1/2” 3/4” 1”
.33 .46 .61
2.10 2.9 3.4
12.0 14.0 18.0
44 59 70
18 23 29
9 12 15
5.0 6.0 7.0
.90 1.4 1.6
1.6 2.3 2.7
1.50 2.0 2.5
1.10 1.5 2.0
1 1/4” 1 1/2” 2”
.79 .93 1.21
4.8 5.6 7.0
24.0 28.0 36.0
96 116 146
38 46 58
20 23 29
9.0 11.0 15.0
2.5 3.0 3.5
3.6 4.5 5.4
3.5 4.0 5.0
2.5 2.9 3.6
2 1/2” 3” 4”
1.39 1.69 2.40
8.4 10.0 14.0
41.0 52.0 70.0
172 213 285
69 86 116
35 43 57
17.0 21.0 27.0
4.0 5.0 6.5
6.5 8.5 12.0
6.0 7.0 9.5
4.4 5.5 7.2
6” 8” 10”
3.40 4.40 5.70
20.0 26.5 33.5
105 136 172
425 555 703
175 225 285
86 115 141
39. 53. 65.
9.5 14. 16.
17. 22. 27.
15. 19. 23.
11.2 15.3 18.2
12” 14” 16”
6.80 8.20 9.10
40.6 48.5 53.0
196 233 274
815 978 1110
336 395 435
166 195 220
78. 92. 106.
18. 21. 26.
33. 37. 43.
27. 31. 36.
20.2 23.3 27.5
Use the smaller diameter in the column for pipe size. d Smaller diameter = D Larger di diameter SIZE OF PIPE (inches)
ABRU AB RUPT PT CO CONT NTRA RACT CTIO ION N d d d D D D 1/4 1/2 3/4
ABRU AB RUPT PT EN ENLA LARG RGEM EMEN ENT T d d d D D D 1/4 1/2 3/4
45° ELBOW
SQUARE 90° ELBOW
CLOSED RETURN BENDS
STD. TEE
STD. TEE
1/8” 1/4” 3/8”
.40 .50 .65
1.6 2.3 3.0
2.0 3.0 4.0
.50 .70 .90
1.6 2.3 3.0
.40 .50 .65
.30 .40 .50
.16 .22 .29
.74 1.0 1.4
.46 .62 .83
.16 .22 .29
1/2” 3/4” 1”
.80 1.0 1.5
4.0 5.0 6.0
5.0 6.0 7.0
1.10 1.5 2.0
4.0 5.0 6.0
.80 1.0 1.5
.60 .80 1.0
.36 .48 .62
1.6 2.3 2.7
1.2 1.4 1.6
.36 .48 .62
1 1/4” 1 1/2” 2”
1.7 2.0 2.5
8.0 9.5 13.0
9.0 11.0 14.0
2.5 2.9 3.6
8.0 9.5 13.0
1.7 2.0 2.5
1.4 1.6 2.0
.83 .97 1.30
3.6 4.5 5.4
2.3 2.7 3.5
.83 .97 1.30
2 1/2” 3” 4”
3.0 4.0 5.0
15.0 18.0 23.0
16.0 19.0 25.0
4.4 5.5 7.2
6” 8” 10” 12” 14” 16”
8.0 11.0 14.0 16.0 18.0 20.0
34.0 44.0 57.0 66.0 79.0 88.0
40.0 50.0 60.0 72.0 84.0 99.0
11.2 15.3 18.2 20.2 23.3 27.5
15.0 18.0 23.0 34.0 44.0 57.0 66.0 79.0 88.0
3.0 4.0 5.0 8.0 11.0 14.0 16.0 18.0 20.0
2.5 2.9 4.0 5.9 7.6 10.2 12.3 14.3 15.4
1.50 1.80 2.40 3.60 4.50 5.70 6.70 8.20 9.30
6.5 8.0 12.0 17.0 22.0 27.0 33.0 37.0 43.0
4.0 4.8 6.4 10.5 14.2 16.5 18.4 22.3 25.5
1.50 1.80 2.40 3.60 4.50 6.80 7.50 9.00 10.20
Note: 1. 1/8” to 12” nominal nominal sizes are are based on standard standard steel pipe, pipe, 14” to to 24” sizes sizes are ID pipe. pipe. 2. Friction losses are based on screwed screwed connection from 1/8” 1/8” to 4” sizes and flanged connections from 6” to 24”
Appendix H
Typical Typi cal Check Valve Friction Loss Chart
Typical Surace Plate / 90° Discharge Elbow Friction Loss Chart SURFACE PLATE PLATE / 90° DISCHARGE FRICTION LOSS CHART
Appendix H
Steel Pipe Friction Loss & Velocity Chart
Note: Above chart indicates indicates average average values for standard standard weight steel steel pipe. Hazen Hazen - Williams Williams roughness constant (C) = 140.
Equivalent Pipe Capacity Comparison Main Size 2” 3” 4” 6” 8” 10” 12” 14” 16” 18” 20”
Smaller Pipe Size (Number of smaller pipes required to provide carrying capacity equal to a larger pipe) 3/4” 1” 2” 3” 4” 6” 8” 13 39 84 247 530 957
6 18 39 115 247 447 724 1,090
1 2 6 18 39 71 115 174 247 338 447
1 2 6 13 24 39 59 84 115 153
1 2 6 11 18 27 39 53 71
1 2 3 6 9 13 18 24
1 1 2 4 6 8 11
10”
1 1 2 3 4 6
NOTE: Comparing the ratio of the square of diameters will provide provide the capacity equivalent equivalent relationship (ie. (ie. how many 12” lines will will be required to equal the capacity capacity of a 16” line? - (16 ) / (12 ) = 1.77 or 2 - 12” lines
Appendix I
Periodic system
1 H
2 He
Hydrogen
Helium
3 Li
4 Be
5 B
6 C
7 N
8 O
9 F
10 Ne
Lithium
Beryllium
Boron
Carbon
Nitrogen
Oxygen
Fluorine
Neon
11 Na
12 Mg
13 Al
14 Si
15 P
16 S
17 Cl
18 Ar
Sodium
Magnesium
Aluminium
Silicon
Phosphorus
Sulphur
Chlorine
Argon
19 K
20 Ca
21 Sc
22 Ti
23 V
24 Cr
25 Mn
26 Fe
27 Co
28 Ni
29 Cu
30 Zn
31 Ga
32 Ge
33 As
34 Se
35 Br
36 Kr
Potassium
Calcium
Scandium
Titanium
Vanadium
Chromium
Manganese
Iron
Cobalt
Nickel
Copper
Zinc
Gallium
Germanium
Arsenic
Selenium
Bromine
Krypton
37 Rb
Rubidium
38 Sr
39 Y
40 Zr
41 Nb
42 Mo
43 Tc
44 Ru
45 Rh
46 Pd
47 Ag
48 Cd
49 In
50 Sn
51 Sb
52 Te
53 I
54 Xe
Strontium
Yttrium
Zirconium
Niobium
Ruthenium
Rhodium
Palladium
Silver
Cadmium
Indium
Tin
Antimony
Tellurium
Iodine
Xenon
55 Cs
56 Ba
57 La
72 Hf
73 Ta
74 W
75 Re
76 Os
77 Ir
78 Pt
79 Au
80 Hg
81 Tl
82 Pb
83 Bi
84 Po
85 At
86 Rn
Caesium
Barium
Lutetium
Hafnium
Tantalum
Tungsten
Rhenium
Osmium
Iridium
Platinum
Gold
Mercury
Thallium
Lead
Bismuth
Polonium
Astatine
Radon
87 Fr
88 Ra
89 Ac
104 Rf
105 Db
106 Sg
107 Bh
108 Hs
109 Mt
110 Ds
111 Rg
113 Uut
114 UUq
115 UUp
116 UUh
117 UUs
118 UUd
Francium
Radium
Actinium
Rutherfordium
Dubnium
Seaborgium
Bohrium
Hassium
58 Ce
59
60 Nd
61 Pm
Cerium
Praseodymium
90 Th
91 Pa
92 U
Thorium
Protactinium
Uranium
Molybdenum Technetium
Pr
112 Uub
Meitnerium Damstadtium Roentgenium Ununbium
Ununtrium Ununquadium
Sm
63 Eu
64 Gd
65 Tb
66 Dy
67 Ho
68 Er
69 Tm
70 Yb
71 Lu
Samarium
Europium
Gadolinium
Terbium
Dysprosium
Holmium
Erbium
Thulium
Ytterbium
Lutetium
93 Np
94 Pu
95 Am
96 Cm
97 Bk
98 Cf
99 Es
100 Fm
101 Md
102 No
103 Lr
Neptunium
Plutonium
Americium
Curium
Berkelium
Californium
Einsteinium
Fernium
Mendelevium
Nobelium
Lawrencium
Neodymium Promethium
62
Appendix J
Pump standards Pump standards: ASME B73.1-2001 ASME B73.2-2003 EN 733 EN 22858
Speciications or horizontal end suction centriugal pumps or chemical process Speciications or vertical in-line centriugal pumps or chemical process End-suction centriugal pumps, rating with 145.03 psi with bearing bracket End-suction centriugal pumps (rating 232.06 psi) - Designation, nominal duty point and dimensions
Pump-related standards: ANSI/HI 1.6 ANSI/HI 1.3
ISO 3661 EN 12756 EN 1092 ISO 7005 DIN 24296
Centriugal tests; detailed procedures on the setup and conduction o hydrostatic and perormance tests Rotodynamic (centriugal) pump applications; the standard cover the design and application o centriugal pumps, pump classiications, impeller types, casing conigurations, mechanical eatures, perormance, selection criteria, and noise levels End-suction centriugal pumps - Base plate and installation dimensions Mechanical seals - Principal dimensions, designation and material codes Flanges and their joints - Circular langes or pipes, valves, ittings and accessories, PN-designated Metallic langes Pumps, and pump units or liquids: Spare parts
Speciications,, etc: Speciications ASME/ANSI B16.5-1996 B16.5-1996 ISO 9905 ISO 5199 ISO 9908 ISO 9906 EN 10204 ISO/FDIS 10816
Pipe langes langes and and langed langed ittings ittings Technical speciications or centriugal pumps - Class 1 Technical speciications or centriugal pumps - Class 2 Technical speciications or centriugal pumps - Class 3 Rotodynamic pumps - Hydraulic perormance tests -Grades 1 and 2 Metallic products - Types o inspection documents Mechanical vibration - Evaluation o machine vibration by measurements on non-rotating parts
Motor standards: Nema MG 1-2007 EN 60034/IEC 34
Inormation guide or general purpose industrial AC small and medium squirrel-cage induction motor standards Rotating electrical machines
Appendix K
Viscosity
Viscosity o typical liquids as a unction o liquid temperature The graph shows the viscosity o typical liquids at dierent temperatures. As it appears rom the graph, the viscosity decreases when the temperature increases.
Kinematic viscosity is measured in centiStokes [cSt] (1 cSt = 10-6 m2/s). The unit [SSU] Saybolt Universal is also used in connection with kinematic viscosity. The graph below shows the relationship between kinematic viscosity in [cSt] and viscosity in [SSU]. The SAE-number is also indicated in the graph. For kinematic viscosity above 60 cSt, the Saybolt Universal viscosity is calculated by the ollowing ormula: [SSU] = 4.62 . [cSt]
cSt 10000
The densities shown in the graph are or 68° F
8 V 6 4
Glycerol ρ: 1260
Kinematic viscosity centiStokes cSt
1
2
2
1000 8
3
6 4
Silicone oil
4 5
Fuel oil Fuel 2
8
20
Fruit juice ρ: 1000 Heavy Heavy 980
ρ:
4
Mean
dle oil Spindle Spin ρ: 850
2
40
100
30 40 50
200 300
ρ: 955
Gas and diesel oil ρ: 88 0 880
10
35
10
Cottonseed oil ρ: 900 6
32
50
Olive oil ρ: 900
100
Sekunder Saybolt Universal SSU
100
400 500 SAE 10
Light 930
8
ρ:
6
Silicone oil ρ: 1000 Milk ρ: 1030
4 ρ: 800
200
1000
300
Petroleu Petro leum m
400 500
Aniline ρ: 1030
2
Ethyl Alkohol
1.0
ρ:
1000
770
SAE 40
10000
SAE 60
Water ρ: 1000 Acetone ρ: 790
Acetic acid ρ: 1050
Ether ρ: 700 2
10
20
30
40
2000 3000
SAE 70
4000 5000
20000
10000
40000 50000
20000
100000
30000
Mercury ρ: 13570
t
0.1 0
SAE 50
Silicone oil Silicone
Petrol ρ: 750
4
SAE 30
4000 5000
8 6
SAE 20
2000 3000
- 10
SAE no. ( at 68o F)
50
60
70
80
90
100°C
30000 40000 50000
100000
200000
Appendix K
Ethylene glycol Density of Aqueous Solutions of Ethylene Glycol Concentrations in Volume Percent Ethylene Glycol Temp., °F -3 0 -2 0 -1 0 0 10 20
10% -
20%
30%
-
-
40% -
50% 68.12
67.04
68.05 64.98
65.93
66.97 66.89
67.90 67.80
64.83
65. 85
66. 80
67.70
30 40
63.69 63.61
64.75 64.66
65. 76 65. 66
66. 70 66. 59
67.59 67.47
50 60 70
63.52 63.42 63.31
64.56 64.45 64.33
65. 55 65. 43 65. 30
66. 47 66. 34 66. 20
67.34 67.20 67.05
80 90
63.19 63.07
64.21 64.07
65. 17 65. 02
66.05 65.90
66.90 66.73
100 110
62.93 62.97
63.93 63.77
64. 86 64. 70
65. 73 65. 56
66.55 66.37
120 130 140
62.63 62.47 62.30
63.61 63.43 63. 25
64. 52 64. 34 64. 15
65.37 65.18 64.98
66.17 65.97 65.75
150 160
62.11 61.92
63. 06 62. 86
63. 95 63. 73
64.76 64.54
65.53 65.30
170 180
61.72 61.51
62. 64 62. 42
63. 51 63.28
64.31 64.07
65.05 64.80
190 200 210
61.29 61.06 60. 82
62. 19 61. 95 61. 71
63.04 62.79 62.53
63.82 63.56 63.29
64. 54 64. 27 63. 99
220 230
60. 57 60. 31
61. 45 61. 18
62.27 61.99
63.01 62.72
63. 70 63. 40
240 250
60. 05 59. 77
60. 90 60.62
61.70 61.40
62.43 62.12
63. 10 62. 78
Note: Density in lb/f t3.
Viscosity of Aqueous Solutions of Ethylene Glycol Concentrations in Volume Percent Ethylene Glycol Temp., °F
10%
20%
30%
40%
50%
-
-
-
0.0428 0.0271
0 . 01 32 0 . 00 92
0. 0 183 0. 0 130
10 20
-
0.0026
0. 004 6 0. 0 036
0 . 00 68 0. 0 052
0. 0 096 0 . 007 3
30 40 50
0 . 001 5 0 . 001 2 0 . 001 0
0. 00 21 0. 00 17 0. 00 15
0. 0 029 0. 0 024 0. 0 020
0. 0 041 0. 0 033 0. 0 027
0. 005 7 0. 004 5 0. 003 7
60 70
0 . 000 9 0 . 000 8
0. 00 12 0. 00 11
0. 0 017 0. 0 014
0. 0 023 0. 0 019
0. 003 1 0. 002 6
80 90
0 . 000 7 0 . 000 6
0. 00 09 0. 00 08
0. 0 012 0. 0 011
0. 0 017 0. 0 014
0. 002 2 0. 001 9
100 110 120
0 . 00 06 0 . 00 05 0 . 00 05
0. 00 07 0. 00 07 0. 0 006
0. 0 009 0. 0 008 0. 0 007
0. 0 013 0. 0 011 0. 0010
0. 001 6 0 . 001 4 0 . 001 2
130 140
0 . 00 04 0. 00 04
0. 0 005 0. 0 005
0. 0 007 0. 0 006
0. 000 9 0. 000 8
0 . 001 1 0 . 001 0
150 160
0. 00 04 0. 00 03
0. 0 005 0. 0 004
0. 0 006 0. 0 005
0. 000 7 0 . 000 6
0 . 000 9 0 . 00 08
170 180 190
0. 0 003 0. 0 003 0. 0 003
0. 0 004 0. 0 004 0. 0 00 3
0. 0005 0. 000 4 0. 000 4
0 . 000 6 0 . 000 5 0 . 000 5
0 . 00 07 0 . 00 06 0. 00 06
200 210
0. 0 002 0. 0 002
0. 0 00 3 0. 000 3
0. 000 4 0 . 000 3
0 . 000 5 0 . 00 04
0. 00 05 0. 00 05
220 230 240
0. 0 002 0. 0 002 0. 0 002
0. 000 3 0. 000 3 0. 000 2
0 . 000 3 0 . 000 3 0 . 000 3
0 . 00 04 0 . 00 04 0. 00 03
0. 00 04 0. 00 04 0. 0 004
250
0. 0 002
0. 000 2
0 . 000 3
0. 00 03
0. 0 003
-3 0 -2 0 -1 0 0
Appendix K
Propylene glycol Density of Aqueous Solutions of Propylene Glycol Concentrations in Volume Percent Propylene Glycol Temp., °F - 30 - 20 - 10 0 10 20
10 % -
20 %
30 %
-
-
40 % -
5 0% 66.46 66.35
65.71 65.60 65.48
66.23 66.11 65.97
64.23
65.00 64.90
30 40
63. 38 63. 30
64. 14 64. 03
64. 79 64. 67
65. 35 65. 21
65. 82 65. 67
50 60
63. 20 63. 10
63. 92 63. 79
64. 53 64. 39
65. 06 64. 90
65. 50 65. 33
70 80 90
62. 98 62. 86 62. 73
63. 66 63. 52 63. 37
64. 24 64. 08 63. 91
64. 73 64. 55 64. 36
65. 14 64. 95 64. 74
100 110 120
62.59 62.44 62.28
63.20 63.03 62.85
63.73 63.54 63.33
64.16 63.95 63.74
64.53 64.30 64.06
130 140 150
62.11 61.93 61.74
62.66 62.46 62.25
63.12 62.90 62.67
63.51 63.27 63.02
63.82 63.57 63.30
160 170 180
61.54 61.33 61.11
62.03 61.80 61.56
62.43 62.18 61.92
62.76 62.49 62.22
63.03 62.74 62.45
190 200
60.89 60.65
61.31 61.05
61.65 61.37
61.93 61.63
62.14 61.83
210 220 230
60. 41 60. 15 59. 89
60. 78 60. 50 60. 21
61.08 60.78 60.47
61.32 61.00 60.68
61.50 61.17 60.83
240
59. 61
59. 91
60. 15
60. 34
60. 47
250
59. 33
59. 60
59. 82
59. 99
60. 11
5 0%
Note: Density in lb/f t 3.
Viscosity of Aqueous Solutions of Propylene Glycol Concentrations in Volume Percent Propylene Glycol Temp., °F
10 %
20 %
30 %
40 %
-
-
0.0275
0.1049 0.0645 0.0412
10 20 30
-
0.0036
0.0019
0.0028
0.0090 0.0067 0. 0050
0.0183 0.0124 0. 0089
0.0273 0. 0187 0. 0132
40 50
0.0015 0.0013
0. 0023 0. 0019
0. 0039 0. 0030
0. 0065 0. 0049
0. 0096 0. 0072
60 70 80
0.0011 0. 0009 0. 0008
0. 0016 0. 0013 0. 0011
0. 0024 0. 0020 0. 0016
0. 0037 0. 0029 0.0024
0.0055 0.0043 0.0034
90 100
0. 0007 0. 0006
0. 0010 0. 0008
0. 0014 0. 0012
0.0019 0. 0016
0.0027 0.0023
110 120 130
0. 0006 0. 0005 0. 0005
0. 0007 0. 0007 0. 0006
0. 0010 0. 0009 0. 0008
0. 0013 0. 0011 0. 0010
0.0019 0.0016 0.0014
140 150 160
0. 0004 0. 0004 0. 0003
0. 0005 0. 0005 0. 0004
0. 0007 0. 0006 0. 0006
0. 0009 0. 0008 0. 0007
0.0012 0.0010 0.0009
170 180 190
0. 0003 0. 0003 0. 0003
0. 0004 0. 0004 0. 0003
0. 0005 0. 0005 0. 0004
0. 0006 0. 0006 0. 0005
0.0008 0.0007 0.0007
200 210 220
0. 0003 0. 0002 0. 0002
0. 0003 0. 0003 0. 0003
0. 0004 0. 0004 0. 0003
0. 0005 0. 0005 0. 0004
0.0006 0.0005 0.0005
230 240
0. 0002 0. 0002
0. 0003 0. 0002
0. 0003 0. 0003
0. 0004 0. 0004
0.0005 0.0004
250
0. 0002
0. 0002
0. 0003
0. 0003
0.0004
- 30 -2 0 -1 0 0
-
Appendix K
Sodium hydroxide ρ
ν 3
[lb/ft ] Concentration wt % = Temperature
[cSt]
ρ
ρ
ν 3
[lb/ft ]
5%
[c St St]
ν 3
[lb/ft ]
10%
[cSt]
ρ
ν 3
[lb/ft ]
15%
[ cS cS t] t]
20%
ρ
ρ
ν 3
[lb/ft ]
[ cS cS t] t]
[lb/ft ]
25%
ρ
ν 3
[ cS cS t] t]
ν 3
[lb/ft ]
30 %
[ cS cS t] t]
ρ
ν 3
[lb/ft ]
35%
[ cS cS t] t]
4 0%
ρ
ν 3
[lb/ft ]
[ cS cS t] t]
45%
ρ
ρ
ν 3
[lb/ft ]
[ cS cS t] t]
50%
ν 3
[lb/ft ]
32
66.17
69.73
73.29
76.78
80.21
83.27
86.40
89.58
92.58
95.51
97.32
41
66.04
69.60
73.16
76.59
80.09
83.15
86.21
89.20
92.39
95.38
97. 13
50
65.98
69.48
73.04
76.41
79.90
83.02
85.96
88.83
92.2 6
95.20
96. 95
59
65.92
69.35
72.85
76.28
79.72
82.77
85.65
88.64
91. 83
94.7 6
96.51
68
65.79
1.3
69.23
77
65.67
1.1
69.10
86
65.54
1.0
68.92
1.2
72.66
2.5
1.5
72.54
2.1
1.3
72.35
1.8
72.22
1.6
1.7
3.6
79.53
75.97
3.1
79.34
5.1
82.34
8.3
85.15
13.3
75.78
2.7
79.15
4.0
82.09
6.5
84.90
9.9
75.60
2.3
78.97
3.4
81.90
5.5
84.71
8.2
2.8
81.71
4.5
84.46
2.6
81.53
3.9
84.09 83.65
76.09
95
65.42
0.9
68.79
104
65.29
0.8
68.67
1.1
72.04
1.4
75.41
2.0
78.78
113
65.17
0.7
68.48
1.0
71.85
1.3
75.22
1.8
78.59
6.2
8 2. 2.52
10.1
122
65.04
0.7
68.29
0.9
71.66
1.2
75.03
1.6
78.40
2.3
81.28
3.3
131
64.86
0.6
68.17
0.8
71.48
1.0
74.85
1.5
78.22
2.0
81.09
2.9
140
64.67
0.6
67.98
0.7
71.35
0.9
74.66
1.3
78.03
1.8
80.84
2.4
149
64.48
0.5
67.79
0.7
71.16
0.9
74.47
1.2
77.78
1.6
158
64.30
0.5
67.60
0.6
70.98
0.8
74.28
1.1
77.59
1.5
167
64.11
67.42
70.79
74.03
77.41
176
63.98
67.23
70.60
73.85
77.22
lb/ft3
38.2
94.32
51. 8
8 8. 8. 21 21
1 9. 9. 9
91 .2 .2 0
2 9. 9. 0
94 .1 .1 4
3 9. 0
8 8. 8. 02 02
1 4. 4. 4
90 .9 .95
1 9. 9
93 .8 .8 9
2 6. 6. 2
8 7. 7. 83 83
1 1. 1. 6
90.77
15.9
93.70
20 . 5
6.6
87 .5 .58
8.9
90.52
12.0
93.45
14.7
5.6
87 .1 .14
7.5
90.08
9.9
93. 01
12 .1
4.6
86.7 1
6.0
89.64
7.8
92.58
9.4
95
104
11 3
96. 13
50% 45% 40%
45%
35%
40% 10
30%
35%
25%
30% 81.15
91.39
8 8. 8. 39 39
100 55% 50%
87.39
2 5. 5. 4
16.8
cSt
99.88
93.64
85.33
[c St St]
55%
20% 15% 10% 5%
25% 20%
1
74.91 15%
68.67
10% 5%
0 68
62.42 32
77
86
122
131
140
149
158 °F
50
68
86
104
122
140
158
176
°F
Appendix K
Calcium chloride
Concentration wt % = Temperature
Sodium chloride
ρ
ν
ρ
ν
ρ
ν
ρ
ν
[lb/t3]
[cSt]
[lb/t3]
[cSt]
[lb/t 3]
[cSt]
[lb/t3]
[cSt]
10%
15%
20%
25%
-13
77.72
-4
77.66
5
74.22
14
71.04
3.0
74.16
Concentration wt % = Temperature 7. 7
5
6.3
14
ρ
ν
ρ
ν
ρ
ν
ρ
ν
[lb/t3]
[cSt]
[lb/t3]
[cSt]
[lb/t3]
[cSt]
[lb/t3]
[cSt]
5%
10%
15%
20%
72.54
4.0
69.91
2.9
72.41
3.2
2.2
69.79
2.4
72.29
2.7
4. 3
77.53
5.2
23
3.6
77.47
4.4
32
65.11
1.8
67.42
1.8
69.66
2.0
72.10
2.3
65.04
1.5
67.35
1.6
69.54
1.7
71.97
1.9
1.3
67.23
1.4
69.41
1.5
71.85
1.7
67.54
23
68.04
2.3
70.98
2.6
74.10
3.1
77.34
3.8
41
32
67.92
2.0
70.85
2.2
74.03
2.6
77.22
3.3
50
64.98
41
67.79
1.7
70.79
1.9
73.91
2.3
77.09
2.9
59
64.92
1.1
67.11
1.2
69.29
1.3
71.66
1.5
2.5
68
64.86
1.0
67.04
1.1
69.17
1.2
71.54
1.3
64.73
0.9
66.92
0.9
69.04
1.0
71.41
1.2
64.67
0.8
66.79
0.9
68.85
0.9
71.23
1.1
50
67.73
1.5
70.66
1.7
73.78
2.0
76.97
59
67.60
1.3
70.60
1.5
73.66
1.8
76.78
2.2
77
68
67.54
1.1
70.48
1.3
73.54
1.6
76.66
2.0
86
77
67.54
1.0
70.35
1.2
73.41
1.4
76.53
1.8
86
67.48
0.9
70.23
1.0
73.22
1.3
76.34
1.6
Index
A Absolute pressure Adjusting pump perormance Aluminum ATEX (ATmosphère EXplosible) Austenitic (non-magnetic) Autotransormer starting Axial fow pumps Axial orces
85 106 70 41 68 46 8 14
B Balanced shat seal Basic coupling Bearing Insulated bearing Bellows seal Groundwater pump Bypass control
31 16 51 48 30 23 106
Constant dierential pressure control Constant pressure control Constant temperature control Copper alloys Corrosion Cavitation corrosion Corrosion atigue Crevice corrosion Erosion corrosion Galvanic corrosion Intergranular corrosion Pitting corrosion Selective corrosion Stress corrosion cracking (SCC) Uniorm corrosion Corrosion atigue Coupling Basic coupling Flexible coupling Spacer coupling Crevice corrosion
115 114 115 69 60 63 64 62 63 64 62 61 62 63 61 64 16 16 16 16 62
C Canned motor pump Cartridge seal Casing Double-volute Single-volute Return channel Cast iron Cavitation Cavitation corrosion Centriugal pump Ceramics Close-coupled pump Closed system Coatings Metallic coatings Non-metallic coatings Organic coatings Computer-aided pump selection Control Throttle control Bypass control Speed control
18 32 15 15 15 15 66 10, 89 63 8 71 12, 13, 16 96, 98 73 73 74 74 58 106 107 107 108
D Decommissioning and disposal costs 131 Deep well pump 23 Density 10, 93 Density o water Appendix D Density o brine Appendix K Diaphragm pump 25 Dierential pressure 88 Dierential pressure control 116 Dilatant liquid 55 Direct-on-line starting (DOL) 46 Dosing pump 25 Double mechanical shat seal 33 Double seal in tandem 33 Double seal in back-to-back 34 Double-channel impeller 21 Double-inlet 17 Double-suction impeller 11, 17 Double-volute casing 15 Downtime costs 131
Index
Duty point Dynamic pressure Dynamic viscosity
Index
96 84 54
E Earth-leakage circuit breaker (ELCB) 125 Eciency 10 Eciency at reduced speed 109 Eciency curve 10 Electric motor 40 Flameproo motor 42 Increased saety motor 42 Non-sparking motor 42 EMC directive 123 EMC lter 123 Enclosure class (IP), motor 43 End-suction pump 12 Energy costs 130 Energy savings 111, 114, 117 Environmental costs 130 Erosion corrosion 63 Ethylene propylelediene rubber (EPDM) 72 Expansion joints 80
F Ferritic (magnetic) 68 Ferritic-austenitic or duplex (magnetic) 68 Ferrous alloys 65 Flameproo motor 42 Flexible coupling 16 Floating oundation 79 Flow 83 Mass fow 83 Volume fow 83 Units Appendix B Fluoroelastomers (FKM) 72 Flushing 32 Foundation 78 Floating oundation 79 Floor 79 oundation 79 Vibration dampeners 79 Frame size 44
Frequency converter
47, 108, 118
G Galvanic corrosion Gauge pressure Grey iron
64 85 66
H Head Heat capacity Hermetically sealed pump Horizontal pump Hydraulic power
9, 85 93 18 12, 13 10, 91
I IEC, motor Immersible pump Impeller Double-channel Single-channel Vortex impeller Increased saety motor Initial costs In-line pump Installation and commissioning costs Insulation class Intergranular corrosion
40 22 14, 21 21 21 21 42 129 12, 13 129 44 62
K Kinematic viscosity
54, Appendix K
L Lie cycle costs Example Liquid Dilatant Newtonian Non-Newtonian Plastic fuid Thixotrophic Viscous Long-coupled pump Loss o production costs
N 117, 128 132 54 55 55 55 55 55 54 12, 13, 16 131
40 55 69 72 66 78 74 55 124 42 10, 89
O
M Magnetic drive Maintenance and repair costs Martensitic (magnetic) Mass fow Measuring pressure Mechanical shat seal Bellows seal Cartridge seal Metal bellows seal Rubber bellows seal Function Flushing Metal alloys Ferrous alloys Metal bellows seal Metallic coatings Mixed fow pumps Modiying impeller diameter Motors Motor eciency Motor insulation Motor protection Motor start-up Direct-on-line starting (DOL) Star/delta starting Autotransormer starting Frequency converter Sot starter Mounting o motor (IM) Multistage pump
NEMA, motor standard Newtonian fuid Nickel alloys Nitrile rubber Nodular iron Noise (vibration) Non-metallic coatings Non-Newtonian liquid Non-sinusoidal current Non-sparking motor NPSH (Net Positive Suction Head)
19 131 68 83 85 18, 28 30 32 32 31 29 32 65 65 32 73 8 108, 110 40 49 48 49 46 46 46 46 46, 47 46 43 11, 12, 13, 16
Open system Operating costs Organic coatings O-ring seal Oversized pumps
96, 99 106, 130 74 30 106
P Paints Perfuoroelastomers (FFKM) Phase insulation PI-controller Pitting corrosion Plastic fuid Plastics Positive displacement pump Power consumption Hydraulic power Shat power Pressure Absolute pressure Dierential pressure Dynamic pressure Gauge pressure Measuring pressure Static pressure System pressure Units Vapor pressure
74 72 48 114 61 55 71 24 10, 91 10, 91 91 84 85 88 84 85 85 84 88 85, Appendix A 90, Appendix D
Index
Pressure control Constant dierential pressure control 115 Constant pressure 114 Constant pressure control 114 Constant supply pressure 114 Pressure transmitter (PT) 114 Proportional pressure control 120 PTC thermistors 50 Pulse Width Modulation (PWM) 123 Pump Axial fow pump 8 Borehole pump 23 Canned motor pump 18 Centriugal pump 8 Close-coupled pump 12, 13, 16 Diaphragm pump 25 Dosing pump 25 Hermetically sealed pump 18 Horizontal pump 12, 13 Immersible pump 22 Long-coupled pump 12, 13, 16 Magnetic-driven pump 19 Mixed fow pump 8 Multistage pump 11, 12, 13, 16 Positive displacement pump 24 Radial fow pump 8 Sanitary pump 20 Single-stage pump 15 Split-case pump 12, 13, 17 Standard pump 17 Vertical pump 12, 13 Wastewater pump 21 Pump casing 15 Pump characteristic 9, 96 Pump curve 9 Pump installation 77 Pump perormance curve 9, 96 Pumps connected in series 103 Pumps in parallel 101 Pumps with integrated requency converter 118 Purchase costs 129 PWM (Pulse Width Modulation) 123
Index
Q QH curve
9
R Radial fow pump Radial orces Reinorced insulation Resistances connected in parallel Resistances connected in series Return channel casing Rubber Ethylene propylelediene rubber (EPDM) Fluoroelastomers (FKM) Nitrile rubber (NBK) Perfuoroelastomers (FFKM) Silicone rubber (Q) Rubber bellows seal
8 15 48 98 97 15 72 72 72 72 72 72 30
S Sanitary pump Seal ace Seal gap Selective corrosion Setpoint Shat Shat power Shat seal Balanced shat seal Unbalanced shat seal Silicone rubber (Q) Single resistances Resistances connected in series Single-channel impeller Single-stage pump Single-suction impeller Single-volute casing Sot starter Sound level Sound pressure level Spacer coupling Static head Static lit
20 28 29 62 114 11 91 28 31 31 72 97 97 21 11, 12, 13, 15 11 15 46 81 82 16 99 99
Speed control 106, 108, 110 Variable speed control 108 Speed-controlled pumps in parallel 102 Split-case pump 12, 13, 17 Stainless steel 66 Standard pump 17 Standards 40 IEC, motor 40 NEMA, motor 40 Sanitary standards 20 Standstill heating o motor 51 Star/delta starting 46 Static pressure 84 Steel 65 Stress corrosion cracking (SCC) 63 Stung box 28 Submersible pump 23 System characteristic 96 Closed system 96, 98 Open system 96, 99 System costs 117 System pressure 88
T Temperature Units Thermoplastics Thermosets Thixotrophic liquid Throttle control Throttle valve Titanium Twin pump
93 Appendix B 71 71 55 106, 110-113 107 70 11
U Unbalanced shat seal Uniorm corrosion
31 61
V Vapor pressure Variable speed control Vertical pump Vibration dampeners Vibrations Viscosity Dynamic viscosity Viscous liquid Viscous liquid pump curve Voltage supply Volume fow Units Volute casing Vortex impeller Wastewater pump
90, Appendix D 108 12, 13 79 78 54, Appendix K 54 54 55 47 83 Appendix A 11 21 21
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U.S.A.
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GRUNDFOS Pumps Corporation 17100 West 118th Terrace Olathe, Kansas 66061 Phone: (913) 227-3400 Telefax: (913) 227-3500
GRUNDFOS Canada Inc. 2941 Brighton Road Oakville, Ontario L6H 6C9 Phone: (905) 829-9533 Telefax: (905) 829-9512
Bombas GRUNDFOS de Mexico S.A. de C.V. Boulevard TLC No. 15 Parque Industrial Stiva Aeropuerto C.P. 66600 Apodaca, N.L. Mexico Phone: 011-52-81-8144 4000 Telefax: 011-52-81-8144 4010
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