Abstract: An improved fluid line leak detector of the type including a casing attached to the fluid line having a passageway therethrough forming an integral part of the fluid line, including a valve located within the passageway of the casing for dividing the fluid line into upstream and downstream portions and movable between an open position in which fluid can freely flow from the upstream portion to the downstream portion, and including an auxiliary flow passageway extending between the upstream and downstream portions of the fluid line for providing a passageway from the upstream portion to the downstream portion when the valve is in the closed position.

Abstract: An underground liquid storage tank assembly including an inner vessel, preferably of steel or other strong, economical material; a seamless outer containment shell, preferably of strong corrosion resistant material such as fiberglass reinforced plastic; and an intermediate spacer member between the inner vessel and outer containment shell to hold the two members rigidly together and for allowing the free passage inside the outer containment shell of any liquid that might leak from the inner vessel. Structure is preferably provided inside the outer containment shell to allow the presence of leakage from the inner vessel to be detected.

Abstract: An underground liquid storage tank that limits the filling of the tank to prevent it from being completely filled and to prevent spills from occurring when the tank is filled. The tank includes, in general, a hollow body having a plurality of standard openings through the top thereof for a fill pipe, a vent line, vapor recovery piping, pump system, gauges, etc. A cylindrical skirt is located within the interior of the body conterminous with each of the standard openings to cause an air "pocket" to be left in the top of the hollow body when the tank is filled.

Abstract: Two pressure sensitive switches are hydraulically mounted in an intermittent pressure pipe line, and electrically connected in a battery power line, for, respectively, defining a pressure drop below a range of "off" presssure in the intermittent pressure pipe line, and interconnecting timing, alarm and latching circuits in and with the battery power circuit. The pressure sensitive switch at the upper limit of the pressure drop connects the power circuit to the timing circuit to energize it to cycle for a timing period, and, with the timing circuit, connects to the latching circuit for making it conducting during the timing period of the timing circuit.

Abstract: An underground storage tank is filled with liquid (e.g., gasoline) until the level of the liquid in the tank rises into the fill-pipe leading from the surface of the ground to interior of the tank. The change in elevation of the liquid in the fill-pipe is monitored over a period of time. The temperature of the liquid within the tank is monitored over the same period of time. Evaporation from the surface of the liquid in the fill-pipe is monitored over the same period of time. A change in elevation of the liquid in the fill-pipe below the level caused by expansion or contraction due to temperature change, and by evaporation loss, indicates a leak in the tank.

Abstract: Leaks are detected in liquid storage reservoirs by detecting any change in the level of liquid in the reservoir while monitoring the temperature of the liquid. The improvement of the present invention involves positioning a series of thermistors at strategic locations in the liquid and using an extremely sensitive, digital readout omhmeter to individually detect the resistance characteristics of each thermistor.

Abstract: An underground storage tank is filled with liquid (e.g., gasoline) until the level of the liquid in the tank rises into the fill-pipe leading from the surface of the ground to interior of the tank. A buoyant member is floated on the surface of the liquid in the fill-pipe. The height of the buoyant members and the temperature of the liquid within the tank are monitored over a period of time. Any fall of the buoyant member that is not proportional to any change of temperature of the liquid within the tank indicates a leak in the tank.

Abstract: In a leak detector of the by-pass check-valve type, as described in my U.S. Pat. No. 3,817,087, having a check-valve blocking lever that is pivotal by a leak flow through the by-pass, the leak flow being directed against the blocking lever through a nozzle mounted in slidable cooperation with a sleeve for concentrating the force of the leak flow and for following the blocking lever as it is pivoted thereby, thus maintaining the maximum force thereagainst, and thereby indicating a leak by restricting the opening of the check-valve and normal flow therethrough.