User`s manual

18
Example of case classification in presence of gas:
Ex d IIB T4
European Standard Safety Protection Temperature Class
Method of Protection with Explosion proof Case Gas Group
Table with different types of gas in connection with different temperature classes
Enclosur
e
Group
Referenc
e
Temperature Class
T1 T2 T3 T4 T5 T6
I
Methane
(Firedamp)
IIA
Ammonia
Toluene
Coke-oven
Gas
Carbon
Monoxide
Acetone
Benzene
Naphthalene
Propylene
Propane
Ethyl chloride
Butane
Styrene
Ethane
Iso-octane
Xylene
Methyl ethyl
propyl butyl
oxyl amyl
acetate
Pentane
Heptane
Hexane
Ciclohexane
Kerosene
N-Decane
Butyric
aldehyde
Benzaldehyde
Octane
Acetic-
aldehyde
Methyl-
ether
Ethyl
nitrate
IIB
Town
Gas
Ethylene
Ethylene
Oxide
Sulphurized
-
Hydrogen
Methyl ethyl
ether
Ethyl
ether
IIC
Hydrogen
Water gas
CLASSIFICATION OF ELECTRICAL APPARATUS FOR USE IN THE PRESENCE OF COMBUSTIBLE DUST.
Electrical apparatus in presence of combustible dust are protected according to different methods of protection.
The most common in ITALKRANE applications are tD A21 and tD A22 protections, in which the protection against combustible dust is
obtained by means of an explosion-proof enclosure with mechanical protection in compliance
with EN 61241-1 rule, and “mD” protections where the triggering source is resin encapsulated.
- TEMPERATURE CLASSES FOR COMBUSTIBLE DUST
Electrical apparatus in the presence of combustible dust are classified according to the maximum surface temperature. Such
temperature must be inferior to either the ignition temperature of the dust cloud in the explosive atmosphere or the temperature of a
dust layer that may collect on the enclosures
Maximum Surface Temperature of
Enclosure at 40°
[°C]
Maximum Ignition Temperature
of the Dust Cloud at 40°
Considering the Safety Factor
[°C]
Maximum Ignition Temperature
of a 5 mm Dust layer at 40°
Considering the Safety Factor
[°C]
450 675 525
300 450 375
200 300 275
135 202.5 210
100 150 175
85 127.5 160
Example of classification of enclosures in presence of combustible dust:
Ex tD A21 T135°C IP 55 Mechanical Protection
European Standard Safety Protection Temperature Class
Method of protection with explosion-proof case Dust-proof protection with mechanical protection