Glossary
What is 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).
Equipment certified for a more severe group covers the lighter ones: IIC covers IIB and IIA, IIB covers IIA. Group I is for mining and group III for dust (IIIA, IIIB, IIIC).
The group matters most for flameproof Ex d protection, because the flame paths in the enclosure are designed for it.
Related terms
- 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.
- Flameproof protection (Ex d)
- A protection concept that lets an explosion happen inside the enclosure, which withstands it and cools the escaping flame through its gaps so the surrounding atmosphere does not ignite.