There are situations that occur when customers and servicemen have difficulty lighting pilots on appliances after a natural gas or propane system has been shut off or following an out-of-gas call in a propane system. The inability to light the pilot light is believed to be the result of air getting into the gas system. In some circumstances, customers or servicemen will purge the gas line in order to get the ‘‘air’’ out of the lines. Sometimes this results in flammable gas entering the structure leading to an explosion, flash fire or fire, and subsequently property damage, serious injuries, and sometimes death.