Designation Examples:
Use in gaseous atmospheres:
II 1 G EEx ia IICT4
Use in dusty atmospheres:
II 2 DT90°C IP64
Use for mining applications:
I M2 EEx ia I
Temperature classes :
In the event of malfunction, the maximum
temperature of a surface that may be exposed to
gas (in normal use with "n" type of protection).

(Should not be used for dust ex-designations.)
T1=450°C ~ T2=300°C ~ T3=200°C
T4=135°C ~ T5=100°C ~ T6=85°C
Explosion group :
Data only for devices used in areas
renderedpotentially explosive by gas)
I = Methane (missing)
IIA = Such as Propane
IIB = Such as Ethylene
IIC = Most dangerous group (e.g. Hydrogen)
Device group :
II=All other explosive areas
Category :
1 = Can be used in Zones 0 or 20
2 = Can be used in Zones 1 or 21
3 = Can be used in Zones 2 ore 22
M1 = Missing (In case of firedamp continuation of
operation is possible)
M2 = Missing (Must be switched off in case of
Atmosphere :
G=Gas ~ D=Dust ~ (Missing - no details)
IP Code
(Data only for devices used in areas
rendered potentially explosive by dust).
Figure 1 Contact and foreign body
5 = Protection against dust deposits
6 = Protection against dust penetration
Figure 2 Water protection.

Protection against:
0 = (no protection)
1 = Vertically falling drip water
2 = Drip water on operating devices inclined to
3 = Spray water
4 = Spray water
5 = Jet water
6 = Strong jet water
7 = Temporary immersion
8 = Constinous immersion
Procedure for determining the housing's leak
tightness (A or B)
Max. Surface temperature.
(Data for devices used in areas render potentially explosive by dust - rarely used in gas ex marking). Maximum temperature of a suface do a machine error (normal operation in case of category 3 devices) that can be reached by the ex atmosphere.

Evaluation by the user:
a)Limit temperature 1=2/3 of min temperature of dust present
b)Limit temperature 2= min glow nature of dust present (applies for layer ticknesses of up to 5 mm). The smaller value for the limit temperature must be above the indicated max.surface temperature of the device.
Types of protection
o = oil immersion
p = high-pressure encapsulation
q = sand encapsulation
d = pressure-resistant encapsulation
e = increased safety
ia = increased safety
(permitted for Zone 0*)
ib = increased safety
(sufficient for Zone 1 (+2)
ma = cast encapsulation (for Zone 0*)
mb = sufficient for Zone 1 (+2)
s = special protection
n = normal operation in normal
condition (only for Zone 2)
nA = non-sparking
nC = enclosed break
nR = vapour-proof housing
nL = energy limited
nZ = high-pressure
op = optical radiation (is,pr,sh)
tD = protected by housing (dust)
pD = high-pressure encapsulation (dust)
iD = increased safety (dust)
mD = cast encapsulation (dust)
*) depending on the device category