Explosion-proof equipment within Class II is categorized into: Class IIA, Class IIB, and Class IIC. The ratings follow a hierarchy: IIC > IIB > IIA.
| Anwendungsbereich | Gas-Klassifizierung | Referenzgas | Mindestenergie des Zündfunken |
|---|---|---|---|
| Unter dem Bergwerk | I | Methan | 0,280 mJ |
| Fabriken außerhalb des Bergwerks | IIA | Propan | 0,180 mJ |
| IIB | Ethylen | 0,060 mJ | |
| IIC | Wasserstoff | 0,019 mJ |
Gas detectors rated for IIC explosion-proof conditions are suitable for all flammable gases; however, IIB detectors fail to detect H2 (hydrogen), C2H2 (acetylene), and CS2 (carbon disulfide), which are characteristic of the IIC class.
