Equipment can be made safe to use in hazardous areas by a number of different methods, generally referred to as Types of Protection.
The different methods approach the problem in quite different ways:
 

Intrinsic Safety (EExi): The available electrical energy is kept at too low a level to ignite an explosive atmosphere even under fault conditions.

Flameproof (EExd): The enclosure is designed and installed such that if a flammable mixture enters the enclosure and is ignited, the enclosure will withstand the internal explosion without transmitting the ignition to an explosive atmosphere outside the enclosure.

Pressurisation (EExp): The enclosure is maintained at a pressure above the surrounding atmosphere using a protective gas thereby excluding the explosive atmosphere.

Increased Safety (EExe): Additional measures are taken to reduce the risk of excessive temperatures or other sources of ignition on apparatus which does not produce arcs or sparks in normal service.

Encapsulation (EExm): Contact with the explosive atmosphere is prevented by encapsulating the equipment in a solid epoxy resin.

Oil Immersion (EExo): Contact with the explosive atmosphere is prevented by immersing the equipment in an oil bath.

Powder Filling (EExq): Contact with the explosive atmosphere is prevented by encasing the equipment in an inert powder.

Non-Incendive (EExn): Enclosure are designed to minimise the risk of mechanical damage and ingress of outside atmosphere.