provided herein are couplings useful in the transfer of liquid fuels from a remote storage reservoir to an on - board fuel tank of a motorized vehicle . there is provided a first coupling which is adapted to be in fluid communication with the interior of a vehicle &# 39 ; s fuel tank , and a second coupling which is intended to be in fluid communication with the contents of a remote fuel storage reservoir . the invention also includes a process for charging a fuel reservoir on board of a motorized vehicle from a remote reservoir , wherein the vapor in the fuel reservoir is displaced by an equal volume of fuel delivered from said remote reservoir , and wherein the vapor in said fuel reservoir is simultaneously caused to be transferred to said remote reservoir , thus permitting no escape of the vapor from said fuel reservoir to the surrounding atmosphere . through use of the present invention , spills of fuel are essentially eliminated , and the escape of vapors from the vehicle &# 39 ; s fuel tank are prevented , thus preventing atmospheric hydrocarbon pollution .