Videotec EXPT - Manual (Page 20)

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12.3 GOST-R Mark
1 Ex d eeC T6 Gb
Ex tb eeeC T85˚C Db IP66
Fig. 12
Protection level Explosion-proof
housing for
potentially explosive
environments Gas group Gas temperature
classification Protection level of the
equipment for gas
Dust ignition
protection for zone
types 21-22 Dust group Maximum surface
temperature for dusts Protection level of the
equipment for dust IP protection degree
Tab. 03
12.4 Gas group classification
The table below shows the classification of some gases and vapours, according to the explosion-proof
protection group and the temperature class. For a complete list see IEC/EN 60079-12 and IEC/EN 60079-20.
T1 T2 T3 T4 T5 T6
IIA Acetone N-Butane Petrol Acetaldehyde Ethyl nitrate
Ethanol N-Butyl Diesel fuel Ether
Ethyl acetate Avgas
Ammonia Heating oil
Pure benzene N-Hexane
Acetic acid
Carbon monoxide
Methanol
Propane
Toluene
IIB Ethylene
IIC Hydrogen Acetylene Carbon
disulphide
Tab. 04 The above temperature classes automatically cover the lower classes (T6 is better than T1).
Class IIB also covers class IIA. Class IIC also covers classes IIB and IIA.
TEMPERATURE CLASS T1 T2 T3 T4 T5 T6
Maximum allowed surface temperature (°C) for the
housing* in the corresponding class 450 300 200 135 100 85
Tab. 05 * Normally refers to the maximum ambient temperature of the installation. The lower the ignition temperature of the related
explosive atmosphere, the higher should be the maximum allowed surface temperature of the housing.
The maximum surface temperature is determined for a 5mm-thick layer of powder and the installation
regulations require a margin of 75K between the surface temperature and the ignition temperature of the
powder under consideration.