Implementation date: July 2004
Review date: July 2006
Recently a natural gas supply hose connecting a gas wall outlet to a Clean Work Bench (Safety Cabinet) for use with a Bunsen burner disconnected during the night. The gas had not been turned off at the wall outlet and the subsequent pressure build up in the tubing was sufficient to dislodge it from the connectors.
An average person can easily detect the smell of natural gas (mainly methane) at a concentration as low as 0.3% by volume in air which is roughly 17 times less that the level required for ignition (5.3 - 15.0% (v/v) with air). For this reason gas leaks are usually detected by people prior to reaching concentrations required for ignition. Appliances connected to natural gas should be connected appropriately such that a leak will not occur in the event that the gas supply to the appliance is not shut off correctly and no means of detection is in place.