Explosion Protection Methods

Electrical equipment for hazardous area operation is designed to prevent or contain ignition of a flammable atmosphere through established and approved methods in accordance with International Standard IEC 60079. The primary methods of protection for equipment, their coding and the standards against which they are approved are included in the table below.

Methods of Protection, Coding & Standards

Protection Method Standard Mode of Protection

Protection by Flameproof Enclosure – Ex d

IEC 60079
Part 1
Housing of equipment that can cause ignition within a robust enclosure that can withstand the force of an internal explosion and prevent transmission of the ignition to the external atmosphere
Protection by Pressurised Enclosure – Ex p IEC 60079
Part 2
Housing of equipment that can cause ignition within an enclosure that prevents the ingress of an explosive atmosphere by maintaining a positive pressure differential between the internal area and the external environment. Systems may be sealed, commonly using an inert gas or have a constant positive flow, typically using air drawn from a non-hazardous area
Protection by Increased Safety – Ex e IEC 60079
Part 7
The equipment shall be manufactured in such a way as to contain no parts that may become an ignition source, either due to arcing/sparking or surface temperature.
Protection by Intrinsic Safety – Ex i IEC 60079
Part 11

IEC 60079
Part 25
Systems and equipment shall be designed such that the energy present in the system shall not reach the ignition energy necessary to ignite the flammable atmosphere
Protection by Type ‘n’ IEC 60079
Part 15
Different types of protection applied to ensure that, in normal operation and under specified fault conditions, the equipment is not capable of igniting an explosive atmosphere. Protection types are nA – Non Sparking nC – Protected Sparking nR – Restricted Breathing
Protection by Encapsulation – Ex m IEC 60079
Part 18
Prevents the source of ignition from coming into contact with the flammable atmosphere by encapsulating the source of ignition in a solid resin.
Dust ignition protection by enclosure – Ex t IEC 60079
Part 31
Housing of equipment that can cause ignition inside an enclosure that limits or prevents the ingress of the combustible dust.