Abstract: A system for automatically releasing the pressure built up inside a tank when the liquid level falls below a predetermined level. This system is particularly applicable for use on a hydrocarbon tank truck which receives the vapors from the underground tank being filled, so that the pressure built up during filling can be released into the atmosphere through a filter in order to minimize the hydrocarbons released into the atmosphere when the connections to the underground tank are uncoupled. The system includes a pressure relief line connected to a float valve located inside a tank compartment on one end and to a filter on the other end. The filter can be made out of an adsorbant material which permits it to be cleaned and used over again.

Abstract: In order to prevent malfunctioning of an automatic liquid fuel dispensing nozzle which is being used for vapor recovery while dispensing, the pressure inside the tank (into which liquid fuel is being dispensed) is used as a reference pressure for the actuating diaphragm of the nozzle cut-off arrangement, rather than using atmospheric pressure for this purpose. Displaced vapors from the tank are directed through a vapor recovery boot having a flexible, exterior cylindrical sleeve and an interior of reticulated material which provides passageways for the vapors to travel through.

Abstract: A float valve for use in the vapor return lines of a vapor recovery system for liquid hydrocarbon storage facilities is disclosed. This valve is designed to prevent vapors from flowing against the float and to quickly close when the liquid level reaches the float.

Abstract: For manipulating a length of non-rigid tubing into position around a swing joint (which includes a 90.degree. fitting) in an underground pipe, a rigid guide tube (through which the non-rigid tubing may be passed) is utilized. The lower end of this guide tube is landed in the 90.degree. fitting, and a wedging member or whipstock, manipulatable from the surface, is operated to hold this end of the guide tube solidly in position in the 90.degree. fitting. After the guide tube is thus secured, the non-rigid tubing is passed down through the guide tube and around the 90.degree. fitting into a laterally-extending pipe; then, a foam-forming composition is pumped through the non-rigid tubing into this latter pipe to form a foamed plug therein.

Abstract: In order to prevent malfunctioning of an automatic liquid fuel dispensing nozzle which is being used for vapor recovery while dispensing, the pressure inside the tank (into which liquid fuel is being dispensed) is used as a reference pressure for the actuating diaphragm of the nozzle cut-off arrangement, rather than using atmospheric pressure for this purpose.