ATEX, Intrinsic Safety & Hazardous Area Information

However demanding your application and environment, we can provide you with a complete ATEX monitoring system. Our range of ATEX pressure sensors and transmitters are available in gauge, absolute, vacuum, differential and compound pressure measurement, with custom pressure ranges and all with a 4-20mA output. Our ATEX rated load cells can also be supplied with suitable Zener Barriers enabling you to safely connect the load cells to any electronic device outside of the hazardous area.

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Please note that this page provides helpful information only, detailed reference should be taken from an appropriate accredited agency or organisation.

Protection Concepts
ZoneHazardProtection Concepts
0In which an explosive gas/air mixture is continuously present for long periods.Exia or Exs
1In which an explosive gas/air mixture is likely to occur in normal operation.Exd. Exe, Exib, Exp, Exia, Exs
2In which an explosive gas/air mixture is not likely to occur in normal operation.All concepts suitable for Zone 0 & 1, ExN, ExO and Exq
Standards For Methods Of Protection
Method Of ProtectionPermitted Zone Of Use In UKCode Letter IEC, EX.., CENELEC, EEX
General requirement--
Oil immersion2o
Pressurisation1 or 2p
Powder filling2q
Flameproof1 or 2d
Increased safety1 or 2e
Intrinsic safety* 0, 1 or 2ia or ib
Non-incendive2n #
Encapsulation1 or 2m
Special1 or 2s
* ia: Zone 0, 1, 2 / ib: Zone 1 or 2 but not Zone 0 | # n: used locally in UK
Gas Grouping
Gas # Group CENELEC EN 5014, IECRepresentative Gas
I * (mining)Methane
IIAPropane
IIBEthylene
IICHydrogen
Temperature Classification
T Class / IEC 79-7Max. Surface Temp °C
T1450°C
T2300°C
T3200°C
T4135°C
T5100°C
T685°C
Certification Code (CENELEC marking information - example [EEx ia] IIC T4)
[EExia]IICT4
Associated apparatus*Certified to the CENELEC standardExplosion protectedProtection concept (IS)Associated apparatus*Apparatus group (gas group)Temperature classification (not Gp I)
* (located in safe area and may be connected to hazardous area)
Device Group & Category
Device GroupDevice CategoryZone
IM = Mining-
MiningM 1-
Pit Gas &/or Flammable DustsM 2-
IIG = Gas
Other Areas1 G0, 1, 2
Explosive Atmosphere2 G1, 2
3 G2
D is added after G in the certification class numberD = Dust
(i.e. GD) if device is dust category approved also1 D20, 21, 22
2 D21, 22
3 D22
Explanation of the categories:

1 - Very high safety = device safety must be guaranteed even in case of rare device failures, e.g. simultaneous failure of two components.

2 - High safety = device safety must be guaranteed if frequent failures can be expected, e.g. failure of one component.

3 – Safe in normal operation = device safety must be guaranteed in normal operation.

Note: A number in brackets before device category designation signifies that the device meets the requirements of an additional category to the main one that is specified.
Example: II (1) 2G signifies that the device meets requirements for both 1 G and 2 G categories

ATEX

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Characteristics of Substances

Flashpoint

This is the lowest temperature at which a liquid generates sufficient vapour to support ignition. This vapour can be ignited in many ways including temperature or energy (i.e. a spark).

Ignition Temperature

This is the lowest temperature at which the vapour will be ignited. This defines the temperature class.

Classification of Maximum Surface Temperatures of Electrical Apparatus (CENELEC)
Temp. ClassMax. Surface Temp.
T1<450ºC
T2<300ºC
T3<200ºC
T4<135ºC
T5<100ºC
T6<85ºC

Apparatus Group (Energy Ignition)

All surface industry gases/vapours are classed as Group II gases. Group II is divided into 3 sub groups:

IIA – High energy is required to ignite. Less intense explosion. (Propane)

IIB – Less energy is required to ignite. More intense explosion. (Ethylene)

IIC – Little energy is required to ignite. Most intense explosion. (Hydrogen)

Characteristics Of Some Common Flammable Materials
Gas/VapourFlashpointGas GroupIgnition Temp.Temp. Class
Acetone19ºCIIA535ºCT1
Butane-60ºCIIA365ºCT2
Heptane-4ºCIIA215ºCT3
Ethyl Methyl Ether37ºCIIB190ºCT4
Note: There is no connection between ignition energy and ignition temperature

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