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Classification of gasses,
mists and vapors into
explosion groups
Temperature classes for
device group II
The classification (see table 8) is based on the maximum gap width determined in
experiments or on the minimum ignition current ratio for the explosive atmosphere
in which a device may be installed (see IEC 60079-20-1).
Explosion group IIA contains less dangerous substances, explosion group IIC the
most dangerous substances. Products intended for a particular explosion group may
always also be used in less dangerous zones.
Table 8: Examples for the classification of gasses, mists and vapors into explosion groups
Explosion group
Examples for gasses, mists and vapors
IIA
Acetone, ammonia, gasoline, benzene, carbon dioxide,
ethanol, methane, hydrogen sulfide, propane
IIB
Ethylene, city gas, acetaldehyde
IIC
Hydrogen, carbon disulfide, acetylene
Please note that in atmospheres which are potentially explosive due to explosive
gasses, mists or vapors (zone 0, 1, 2 for which device group II, categories 1G, 2G
and 3G are intended), the maximum surface temperature of the valve must in
addition be below the ignition temperature of the surrounding explosive gas, mist
or vapor.
Based on their maximum surface temperature, these hydraulic products are
classified according to EN 13463-1 and EN 60079-0 into temperature classes T1
to T6. With hydraulic products in device group II and in categories 1G, 2G and 3G,
the temperature class is part of the explosion protection mark, see "Data sheet
24751-XE". It provides information on the suitability of the hydraulic product for the
use in a particular atmosphere which is potentially explosive due to explosive gasses,
mists or vapors.
Table 9: Temperature classes for device group II
Temperature class
T1
T2
T3
T4
T5
T6
Maximum surface temperature
450 °C
300 °C
200 °C
135 °C
100 °C
85 °C
RE 24751-XE-B/04.16, H-4WEH...XE..., Bosch Rexroth AG
Product information
21/52
Dangerousness
medium
high
very high
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