Question & Answers Engineer Interview (Mechanical engineer)
Arranged and Prepared by: Eng. Mohammed Gallow https://goo.gl/bfPctQ
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Q.1) What a sprinkler system in firefighting? In a standard wet-pipe sprinkler system, each sprinkler activates independently when the predetermined heat level is reached. Thus only sprinklers near the fire will operate normally just one or two. This maximizes water pressure over the point of fire origin, and minimizes water damage to the building.
Q.2) What is a dry type sprinkler system? Dry pipe fire sprinkler system. A dry pipe sprinkler system is one in which pipes are filled with pressurized air or nitrogen, rather than water. This air holds a remote valve, known as a dry pipe valve, in a closed position.
Q.3) What does it take to set off a fire sprinkler? Each individual sprinkler head is triggered automatically when the air rising to the ceiling reaches a fire specific temperature of (red bulbs for buildings) 68 degree. Often, only one or two sprinklers are required to fully extinguish a building fire.
Q.4) What is a frangible bulb? The frangible bulb is simple to use, comprising a small thermo bulb made of glass containing a chemical liquid that will expand rapidly when exposed to rising temperatures, bursting the glass fire bulb is and accurately pre-determined temperature, thereby activating the sprinkler.
Q.5) What is a pendant sprinkler head? The upright, pendant sprinklers all produce a hemispherical water distribution pattern below the deflector. Sprinkler operation. During a fire conditions, the thermal-sensitive liquid in the glass bulb expands causing the bulb to shatter, releasing the button and Springfield assembly.
Q.6) What is NFPA 13? NFPA 13 is an installation standard. It does not specify which buildings or structures require sprinkler protection. Rather, once sprinkler protection is required, it provides the requirement for the design and installation of this system.
Q.7) What is a fire hydrant system? Fire hydrant pump systems (also known as fire pumps, hydrant boosters, fire water pumps) are high-pressure water pump designed to increase the firefighting capacity of a building by boosting the pressure in the hydrant service when mains is not enough, or when tank fed.
Q.8) What is the use of burn control valve in firefighting? Zone Control Valve is a system designed to separate the area in case of maintenance and to get the indication of fire zone on a combination of Butterfly Valve, flow switch, Pressure Gauge and Test & Drain Valve. 2
Q.9) What is the fire alarm system? A fire alarm system has a number of devices working together to detect and warn people through visual and audio appliances when smoke, fire, carbon monoxide or other emergencies are present. … Alarms can be either motorized bells or wall mountable Sounders or horns.
Q.10) What is a flow switch in a sprinkler system? Fire suppression. The Water Flow Switch is a mechanical-to-electrical Fire Alarm input device; it tells the fire alarm system that water is flowing in the sprinkler system.
Q.11) Why fire hydrants different colors? Known as NFPA 291, it says fire hydrants using public water supply systems should be painted chrome yellow, and their tops and caps should indicate the available GPM. below 500 GPM should be red , 500-999 GPM should be orange, 1000-1499 GPM should be green, and 1500 GPM or more should be blue.
Q.12) What is a dry riser? A dry riser is a normally empty pipe that can be externally connected to a pressurized water source by firefighters. It is a vertical pipe intended to distribute water to multiple levels of a building a structure as a component of the fire suppression systems.
Q.13) What is a fire hose real? A fire hose (or firehose) is a high-pressure hose that carries water or other fire retardant (such as foam) to a fire to extinguish it. Outdoors, it attaches either to a fire engine or a fire hydrant.
Q.14) What is the flow and tamper switch? Flow switchers detect water movement to drop in pressure, and activate alarms. Tamper switches detect when a sprinkler valve has been partially to fully closed and usually activate the trouble signal at the control, although some cities require them activate alarms.
Q.15) What is the use of flow switch? A sail switch, vane switch or flow switch is a mechanical switch that is switched on or off in response to the flow and non-flow of a fluid such as air a water. A sail switch typically operates through the use of a paddle which get displaced due to the force of fluid moving past it.
Q.16) What is a water flow switch for fire alarm? A water flow detector, commonly produced by system sensor, is an electro-mechanical device designed to send an alarm to a fire alarm panel and/or fire department when a continuous flow of water occurs through the fire sprinkler system's piping from an activated fire sprinkler head a leak in the system. 3
Q.17) What is dry riser testing? Dry risers are used to deliver water within buildings for firefighting purposes . … Inlet connectors are typically contained in accessible, but secure enclosures on the external face of buildings and are identified as a "dry riser Inlet".
Q.18) What is an OS&Y gate valve? One type of valve commonly used to control water flow to fire sprinkler systems is known as an OS&Y gate valve. OS&Y means "outside stem and yoke" or "outside screw yoke". OS&Y gate valves operate by opening and closing via a gate, which lowers into or rises out of the valve.
Q.19) What is the use of pressure switch? A pressure switch is a form of switch that closes an electrical contact when a certain set fluid pressure have been reached on its input. The switch may be designed to make contact either on pressure riser or on pressure fall.
Q.20) What is a water flow sensor? Water flow sensor consists of a plastic valve body, a water rotor, and a hall-effect sensor. When water flows through the rotor, rotor rolls. It speed changes with different rate of flow. The hall-effect sensor outputs the corresponding pulse signal.
Q.21) What is a pre action fire suppression system? The system's discharge is a two-step process: First, the innovative detection system identifies smoke a heat, which activates a pre-action valve that allows water to flow into piping and effectively creates a wet pipe sprinkler system. Second, individual sprinkler heads release to let water flow onto the fire.
Q.22) How do you turn off the fire sprinkler? Tape the padlock heat as a pipe or a wall nearby so you can find it when you need it. Keep the area around your water controls clear. Do not store anything within 1 foot (30 cm) of your water controls. If sprinkler water control valves are ever turned "off " be sure to turn them back on.
Q.23) What is a main drain test? The main drain test is a suitable do-it-yourself project the sprinkler system supplier can perform the test instead. a. Notify the local fire department of the upcoming test if the fire sprinkler system is connected to a central alarm. b. Find the water flow test control valve.
Q.24) How do I manually turn on a sprinkler valve? One way is to simply turn the solenoid (the black cylinder with two wires) counterclockwise a 1/4 to 1/2 turn. To shut off the valve, twist the solenoid clockwise until it is 4
snug on the valve. The other way is to use the bleed screw the same way, loosen the screw enough to release air (1/4 to 1/2 turn).
Q.25) How many sprinkler heads can be on one zone? At different pressures, the sprinkler head a nozzle will consume different amounts of water. For example, at 35 pounds per square inch (PSI) the 5000 Series Rotor using the 3.0 nozzle will use 3.11 gallons per minute (GPM). If your home's water capacity was 10 GPM you could place 3 heads to zone.
Q.26) What are the types of pump sets used and why in firefighting? a. Jockey pump – used when there is a pressure drop of 1 bar. b. Diesel pump – used in case of power shut down. c. Electric pump – Main pump starts instantly in case of fire and will cutoff @ 7 bar.
Q.27) What is fire alarm check valve? It allows flow in one direction and prevents backward flow and with this gives signal to BMS with alarms.
Q.28) What is FM-200 and where is it used? Heptafloropropane is colorless, liquefied compressed gas. It is stored as a liquid and dispensed into the hazard as a colorless, eclectically non-conductive vapor that is clear and does not obscure vision. It is used in communication rooms, electrical rooms, computer rooms etc...
Q.29) Types of detectors? Smoke & Heat detectors.
Q.30) Do we use strainers in fire pumps? Why? No, we don’t use it because the water coming is portable usually o nly in cases where we
are using river or lake water then we require strainers. Else we prefer not to use them as it will reduce suction flow.
Q.31) Radius of a sprinkler? It is 1.5 m.
Q.32) What is the distance between each sprinkler? Its 3 m to 4m.
Q.33) Working pressure of fire system? Its 10 bar.
Q.34) What is Siamese Connection? Used as auxiliary connection through which the fire department can pump water to supplement existing water supplies.
Q.35) What are the Settings of Diesel pump upon how much pressure it is cut off? Don’t know check internet. 5
Q.36) What is OS&Y, Tamper switch, Pressure switch and their working? a. OS&Y valve - Outside screw & Yoke – is used in fire system mains and is used for easy knowing whether it is in open position or closed as we cannot know from a typical gate valve or ball valve. b. Tamper switch - It is a supervisory device located on the control valves of a fire protection system. The tamper switch is a device which, when connected to an alarm panel or sounder, signals a disturbance (opening or closing) at the control valves of the system. c. Pressure Switch - These critical components sense the activation of the system and then electrically secure the ventilation systems operating in the protected space.
Q.37) What is the use of strainer? It is installed before the cooling coil to protect dirt & foreign material entering into the cooling coil /evaporator.
Q.38) What is the use of staircase pressurization? To provide fresh & clean air in the staircase when fire occurs in the floor. The pressurized air keeps the smoke away from the stair wall. It is used for creating positive pressure.
Q.39) Name some fine controlled Valves? Needle valve, Spindle valve, regulating valve, motorized valve etc.
Q.40) What should be height of fire cabinet from floor level? 1 m.
Q.41) What are the different types of sprinkler heads used in fire protection system? Upright sprinkler, Pendent sprinkler, Side wall sprinkler, Pendent Recessed sprinkler, extended side wall sprinkler, extended coverage etc.,
Q.42) What is the test pressure for firefighting pipe network? 1.5 times working pressure.
Q.43) What is the temperature rating for firefighting sprinkler head? 170 F or 76 c. °
°
Q.44) What is the fire department connection known as? Siamese.
Q.45) Name the different types of fire extinguisher? Portable type CO2, Portable type Dry Powder & water.
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Q.46) What are the different types of Valve used in fire protection system? Alarm valve, Zonal valve etc.
Q.47) What the pipe material used for underground fire piping? UPVC, MDPA, RTR.
Q.48) What is zone control valve? It is used in FF system on every floor … it consist of OS & Y Gate valve with tamper switch, Check Valve, pressure gauge, Drain point, Flow meter & Sight glass. “Check FF Notes”.
Q.49) What is the standard length of hose in a hose reel cabinet? 30m.
Q.50) Pipe material used in FF system and which class? ‘Check FF Notes’.
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