What Are ATEX Temperature Classes T1-T6?
T1-T6 temperature classes define the maximum surface temperature permitted for equipment used in hazardous gas and vapor atmospheres. The objective is to keep equipment surfaces below temperatures that could ignite the surrounding atmosphere.
What does the temperature class show?
The Ex temperature class relates to the maximum permitted surface temperature of the equipment under defined operating and fault conditions. It must be compatible with the ignition temperature of the gas or vapor that may be present.
Maximum surface temperatures for T1-T6
The common limits are T1: 450°C, T2: 300°C, T3: 200°C, T4: 135°C, T5: 100°C and T6: 85°C. As the class number increases, the permitted maximum surface temperature decreases.
Match the class to the ignition temperature of the gas
Looking only at the T class is not sufficient unless the ignition temperature of the gas or vapor in the process is known. Material information, process conditions and equipment marking must be evaluated together.
Why does ambient temperature also matter?
Certificates may define a permitted ambient-temperature range. If the actual site temperature falls outside that range, the T class alone does not guarantee suitability. This is especially important in hot process areas and outdoor installations.
T class is not the only selection criterion
Final selection also checks Zone, gas group, protection type, IP rating and installation conditions.