This procedure must be followed when entering confined spaces such as manholes, vaults, boilers, ductwork, vessels, etc. Its intent is to protect entering personnel against such hazards as oxygen deficiency, combustible gas and vapors, toxic gases and vapors, mechanical hazards, entrapment, etc. Confined spaces may be closed on all sides, top and bottom, with entry provided through restricted openings, or may be open completely on one side, top or bottom.
Entry is defined as breaking the plane of the confined space with any part of the body.
At this point a check list must be completed. Note that some instruments test for multiple gases simultaneously. If the presence of a toxic gas or vapor is suspected in a confined space, other than carbon monoxide or hydrogen sulfide, contact Environmental Health and Safety for advice on air sampling. Hot air and steam shall be ventilated from steam vaults before testing the atmosphere. This testing can be accomplished by using the gas meter and the hand-held probe and sampling line attached to the pump.