Division into temperature classes
Explosion proof equipment, installed within an Ex area, is divided into 6 temperature classes (T1 to T6). The temperature class is not – as it is often wrongly believed – the operating temperature range of the equipment, but the maximum permissible surface temperature of the equipment, in relation to + 40°C ambient temperature on any surface area, which may not be exceeded at any time. The maximum surface temperature must remain below the ignition temperature of the surrounding medium at all times. The equipment design requirements increase from T1 to T6.