Glossary · Ex d
What is 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.
Defined in IEC 60079-1 with levels da, db and dc by EPL; db, suitable for Zone 1, is the most common. Used for motors, control panels and transmitters.
A scratch on a flame-path surface, a missing bolt or an uncertified cable gland defeats the protection entirely, which is why Ex d maintenance needs special care.
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).
- Intrinsic safety (Ex i)
- A protection concept that limits the electrical energy in a circuit so it cannot produce an igniting spark or heat, even under fault conditions.
- Equipment Protection Level (EPL)
- The equipment protection level states how safe a device is as an ignition source, and maps directly to the zones where it may be used.