OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 5 Confined Spaces

Section 53 Ventilation and purging

Ventilating means the use of mechanical ventilation to force fresh air into the confined space while workers are working. Purging means the introduction of substances such as an inert gas, steam or water into a confined space to displace or flush out contaminants prior to workers entering the space.

If atmospheric testing identifies that a hazardous atmosphere is present or is likely to be present in a confined space, the space must be ventilated, purged or both before a worker enters the confined space. If ventilating or purging is impractical or does not eliminate the atmospheric hazards, workers are then required to wear appropriate personal protective equipment. Personal protective equipment is not an acceptable method of worker protection from flammable or explosive atmospheres.

If mechanical ventilation is required to maintain a safe work atmosphere within a confined space, the employer must ensure that the ventilation system incorporates a method of alerting workers if the system fails. Workers must be trained in the evacuation procedures to be used if the ventilation system fails.