Patent ID: 7401625

Claim:
A fuel supply system for supplying liquefied gas as fuel to a combustion engine, the system comprising: a container of liquefied gas, said liquefied gas being present in said container in a vapor phase and a liquid phase; a fuel supply line for supplying the liquefied gas from the container to the engine; the supply line having an inlet end at a predetermined level in the container; whereby liquefied gas in the liquid phase will be supplied through the supply line to operate the engine when the level of the liquid phase of the liquefied gas is above the inlet end of the supply line and wherein liquefied gas in the vapor phase will be supplied through the supply line to the engine to operate the engine for a remaining limited time period when the liquid phase of the liquefied gas level in the container falls below the inlet end of the supply line; and a phase change detector positioned in the fuel supply line externally of said liquefied gas container; said phase change detector detecting the occurrence of a change from the liquid phase of the liquefied gas to the vapor phase of the liquefied gas in the supply line when the liquid phase in the container falls below the supply line inlet, a warning signal activated by said system in response to the detection of said change from the liquid phase to the vapor phase of the liquefied gas in said supply line, said warning signal being indicative of a low level of liquefied gas in the liquid phase in said container to warn an operator that the engine will shortly run out of fuel.