The topic of Explosive Atmospheres is concerned with the management, design, installation, operation and maintenance of systems that reduce the risk of electrical ignition sources arising from:
- fixed electrical installations;
- moveable electrical equipment;
- lightning in relation to structures with a risk of explosion;
- electrostatic hazards;
- radio frequency radiation;
- isolating joints, for example in cathodic protection systems;
and the mitigation of releases using:
- flammable and toxic gas detection;
- fire detection.
The key benchmark technical standards relating to these sub-topics are listed in the EC&I Operational Delivery Guide.
The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) require employers to put control measures in place to either remove fire and explosion risks or, where this is not possible, control them. Where explosion risks cannot be removed, electrical sources of ignition should be managed by:
Design of equipment and structures, for example by:
- the selection of explosion protected (Ex) equipment and/or systems (see pages on ATEX and explosive atmospheres);
- avoiding hazards due to static electricity by bonding all conductors together and to earth;
- installing lightning protection systems appropriate to the construction and contents of structures;
- detuning structures capable of acting as RF antennae in explosive atmospheres within the vulnerable zones of transmitters;
- application of a protective coating to cathodic protection isolating joints to prevent accidental contact.
Maintenance and inspection of equipment and structures, for example by:
- initial inspection before plant or equipment is brought into service;
- ongoing periodic inspection of explosion protected (Ex) equipment and/or systems (see pages on ATEX and explosive atmospheres)
- monitoring of static earthing;
- maintenance and inspection of lightning protection systems;
- periodic inspection of above ground isolating joints, for example in cathodic protection systems.