IEC

Marking of Weighing Equipment for Hazardous Areas Typical Marking Example Explosion Protection Marking

Group / Class, Area Classificat Classification ion

Protection Method

Explosion Group

Temperature Class

II 2 G/D

Ex ib

IIB

T4

Ex ib

IIB

T4

AEx ib

IIB

T4

FM

NEC 505

Group A, B, C, D, E, F

T4

FM / UL

NEC 500

EPL*

Directive

Legislation

ATEX

IEC / CENELEC (Europe)

Class I Zo Zone 1 Class I, II, III Division 1

Da

IECEx

(USA)

(USA) *Equipment Protection Level

 Group, Area Classication CENELEC / IEC / ATEX Equipment Group

Area Classification ATEX 94/9/EC

Equipment Protection Level

II

Protection Method Classified Area Explosive atmosphere present

ATEX

CENELEC/ IEC

Gas / Vapor

Dust

1G/1D*

Ga/Da*

Zone 0

Zone 20

Continuously  or for long periods of time

2G/2D*

Gb/Db*

Zone 1

Zone 21

Occasionally in normal operation

3G/3D*

Gc/Dc*

Zone 2

Zone 22

Infrequently or for short periods of time

Type of Protection

Symbol

Increased Safety

Ex e

Temperature Class

NEC 505 / CENELEC

NEC 506/ CENELEC

Explosive atmosphere present

Zo n e 0

Zone 20

Continuously or for long periods of time

Zo n e 1

Zone 21

Occasionally in normal operation

Division 1

Division 2

Zo n e 2

Zone 22

Maximum Surface Temperature

NEC 500

450ºC

T1

T1

300ºC

T2

T2

Infrequently or for short periods of time or do not likely to occur  in normal operation

Equipment Substance Classification Group

 Acetylene

 A

Hydrogen

B

IECEx / ATEX Group

Ex ia

Class I Ethylene

C

Propane

D Mining

NEC 505 / CENELEC

Pressurized

280ºC

T2A

260ºC

T2B

230ºC

T2C

IIB

500

IIA

IIIC

215ºC

T2D

200ºC

T3

180ºC

T3A

G Class III

–

Remote Weighing Display

 Application Terminal Terminal

1

II 2 G

1

II 3 G

2

II 1 G

1

II 2 G

1

II 3 G

2

Keep the explosive atmosphere away from the ignition source

II 2 G II 3 G

1 2

Ex nA

non-sparking device

II 3 G

2

Ex nC

sparking devices and components

II 3 G

2

restricted

II 3 G

2

Ex mb

Ex o Ex “o”

T3

Keep the explosive atmosphere away from any source of ignition

IEC EN 60079-7 ISA/UL 60079-7

IEC EN 60079-11 UL 60079-11 FM 3610

IEC EN 60079-2 UL 60079-2 FM 3620

IEC EN 60079-18 ISA/UL 60079-18

IEC EN 60079-6 ISA/UL 60079-6 FM 3600

Ex “n”

IEC EN 60079-15 ISA/UL 60079-15 FM 3600

165ºC

T3B

Ex n R

160ºC

T3C

Ex nL

limited Energy

II 3 G

2

135ºC

T4

Ex d

Contain the explosion, quench the flame

II 1 G II 2 G

1 2

IEC EN 60079-1 ISA/UL 60079-1

Special enclosure design, measuring equipment 

II 1 D II 2 D

1 2

IEC EN 61241-1 IEC EN 60079-31

T4

Flame Proof 

Ex “d”

T4A

III B

100ºC

T5

T5

III A

85ºC

T6

T6

505

500

Protection by enclosure

tD Ex “tD”

Hazardous Area

Safe Area

Hazardous Area

II 1 G

1, 2

Ex ma

Oil Immersion

1 2

II 2 G II 3 G

Ex mc

120ºC

F

Non-conductive Dusts

Purge enclosure with the inert pressurized air

Ex p

Encapsulation

E Class II

Combustible Fibers and Flyings

Limit energy; no sparks or surface temperature

E x ib

Protection „n“

I

Combustible Metal Dusts Conductive Dusts

Intrinsic Safety

II 2 G II 3 G

NEC

IIC

Methane

Dust / water tight enclosure

Ex “m”

Explosion Substance Group NEC / IECEX / ATEX Substance

Standard

Ex ic

Area Classication NEC500

Principle Categ Cat egory ory Div Divisi ision on

*G = Gas / D = Dust 

Class, Area Classication NEC 500/ 505 /506

Design

Safe Area Communication Interface Module

 Application Terminal Terminal

Communication Communicatio n Interface Module

RS232 Printer RS232

Ethernet 

RS232 Tank on Weigh Modules

PC connection I/O Control

Remote Terminal Power Supply

Junction Box  AC Source Power Supply

Hazardous Solutions Zone – 1/21, Division 1

RS232 Printer

Crossed Ethernet cable

 Analog Platform PC connection Hazardous Solutions Zone – 1/21, Division 1

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