Selection of explosion protected
equipment for hazardous locations
January 29th, 2016, Published in Articles: EngineerIT, Articles: Vector
by Pieter Coetzee, Explotac
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While national regulations exist in some countries, there is an urgent need for an international approach to curb
explosion-related industrial accidents wherever workers and communities are exposed explosion risk
All workers in hazardous locations must be declared competent to express their opinions in compliance with the Electrical
Machinery Regulation (EMR). Human error or incompetency has been found to be at least one part of the domino effect in
major disasters.
All hazardous locations must comply with the Occupational
Health and Safety (OHS) Act, as well as with the relevant
codes of practice and standards. Section 9 of the Electrical
Machinery Regulation (EMR) requires that all hazardous
areas be classified and equipment used in such areas be
certified. All explosion protective equipment (EPE) must be
certified by a locally-approved test laboratory (ATL), as
required by regulation ARP 0108. Workers in hazardous
locations must receive proper Ex training and be declared
competent.
A fire or explosion can only occur if three things are present:
fuel, oxygen and an ignition spark. The required ratio of fuel
and oxygen varies with each fuel (gas or vapour).
Suppressing or separating one or more of these three
components can avoid a fire or explosion.
Step 1
Fig. 1: Fire triangle.
Establish if it is a hazardous area due to the presence of
explosive gas or dust and divide the area into zones of riskof-release of gas, vapour or dust. The process of determining the type and size of these hazardous zones is called area
classification. The guidance on assessing the extent of the hazard is given in the current edition of IEC/SANS 60079-10-1
for gas zones. The applicable standard for dust zones is IEC/SANS 60079-10-2 and the dust zones consist of zones 20; 21
and 22. Area classification takes into account gas groups and temperature classes.