Glossary
What is Temperature class (T1 to T6)?
The highest temperature a device’s surface can reach; it must stay below the auto-ignition temperature of the gas on site.
T1 up to 450 °C, T2 300 °C, T3 200 °C, T4 135 °C, T5 100 °C and T6 85 °C.
Example: diethyl ether auto-ignites at about 160 °C, so it needs at least T4. Hydrogen ignites at about 560 °C, so T1 is enough thermally, but it needs gas group IIC.
Related terms
- Gas groups (IIA, IIB, IIC)
- Gases classified by how easily they ignite and pass a flame: IIA least severe (propane), IIB (ethylene), IIC most severe (hydrogen, acetylene).
- IECEx
- The international certification scheme for equipment in explosive atmospheres, run by the IEC and based on the IEC 60079 series of standards.