In a true "out of gas" situation, no pressure remains in the system. It is possible for the liquid level gauge to show 0% while some pressure remains in the tank and associated piping. Whether or not any pressure actually remains can easily be determined by the service agent by manually depressing the relief valve. If no pressure remains in the system, them filling the tank and leaving the tank valve open would be reintroducing gas into the system which is NOT PERMITTED. This would be no different than restoring a natural gas service after service has been discontinued.

New systems are required to be subjected to a "pressure test" before gas is introduced. With existing systems, before any gas (LP or natural) is reintroduced a "leak test" must be conducted. NFPA 54 details the procedures for each type of test.

If the situation exists where the individual filling the tank cannot preform the required leak test or the system fails the test then the critical question is what are the appropriate precautions to be taken to prevent someone from opening up the valve at a later time before the system is proven to be leak tight.

The NLPGA does publish industry safety sheet/procedures/guidelines one of which specifically deals with "out of gas" calls. This particular safety sheet calls for the valve to be left in the off position and a written notice (tag) be left indicating that gas must not be turned on until a proper leak test can be conducted. They also have available for purchase tags for just this purpose.

I also know from past case experience that Ranger Insurance (one of major insurance carrier for the gas industry) has a safety policy that requires their insured to put a lock on the valve or the tank cover to prevent gas from being introduced.

Hope this helps

James G. Munger, PhD, FIFireE, CFPS
www.qdotengineering.com
W3NFA