A major design consideration for modifying equipment for
use in hazardous areas is the Equipment Temperature Rating. Electrical
and other equipment must be rated according to the ‘T’ Rating
System which certifies that operating temperatures are
significantly below the ignition point of particular flammable
gases found in hazardous areas. The T ratings for
particular gases and dusts ogether with their maximum operating
temperature are shown below.
GASES AND VAPOURS
GROUP II
Temperature class of equipment
Maximum surface temperature
of equipment ºC
Minimum ignition temperature
of gas or vapour ºC
T1
450
450
T2
300
300
T3
200
200
T4
135
135
T5
100
100
T6
85
85
DUSTS
Temperature class of equipment
Maximum surface temperature
of equipment ºC
Minimum cloud or layer
* ignition temperature of dust ºC
T1
450
525
T2
300
375
T3
200
275
T4
135
210
T5
100
175
T6
85
160
* based on practice A of AS/NZS 6124.2.1 equipment for dust layers up to 5mm thick
