Abstract: A vapor recovery system is disclosed that utilizes a crystal oscillator for sensing the presence of hydrocarbon in the vapor emissions emanating from a fuel tank during refueling. The crystal oscillator is coated with a layer of material having a sensitivity for hydrocarbon. In response to any interaction between the coating layer and hydrocarbon, the crystal oscillator experiences a shift in its oscillation frequency relative to the fundamental resonance frequency. The frequency shift is representative of the hydrocarbon concentration in the vapor emissions. A control signal based on the frequency shift is generated and then used to adjust the operating speed of the vapor pump.

Abstract: A method and apparatus is disclosed for sensing hydrocarbon in the vapor path of fuel dispensers using a fiber-optic sensor. The sensor includes an absorber-expander sensing structure mechanically coupled to the fiber body and responsive to the presence of effluent fuel components for absorbing the hydrocarbon therein and expanding in response thereto. The expansion activity has the effect of generating a microbend deformation in the fiber, producing detectable changes in the optical throughput representing the concentration of hydrocarbon that is sensed by the absorber-expander element. The fiber-optic sensor is particularly useful in a vapor recovery system by providing an optical signal that is representative of the ambient hydrocarbon concentration.

Abstract: A vapor recovery system is disclosed that provides direct measurements of the oxygen concentration within fugitive vapor emissions displaced from a fuel tank during refueling activity. The hydrocarbon concentration is derived from the oxygen concentration and used to adjust the operating speed of a vapor pump so as to minimize the presence of oxygen in the vapor recovery line.

Abstract: The infrared dual beam hydrogen fluoride (HF) gas detector comprises a light source for generating a light beam, a reference filter which passes light at a wavelength in the infrared range, such wavelength light being highly not absorbed by HF gas, an HF sensing filter which passes light at a wavelength in the infrared range, such wavelength light being highly absorbed by HF gas, structure for directing the light beam through a space containing vapor under investigation and alternately through each filter, a first sensor for sensing the light transmitted through the reference filter and for generating a first signal, a second sensor for sensing the light transmitted through the HF sensing filter and for generating a second signal, first circuitry for demodulating and amplifying the first signal generated by light transmitted through the reference filter, second circuitry for demodulating and amplifying the second signal generated by light transmitted through the HF sensing filter, and a comparator for compari

Abstract: An interface determining device includes a casing positioned in an above ground storage tank and apparatus is provided for establishing a clean interface in the casing between the liquid product in the tank and water in the tank. Also, a leak detector including a sensor assembly comprising an array of conductivity sensors for sensing conductivity mounted in a casing is positioned at the bottom of an above ground storage tank. Apparatus is provided for establishing a clean interface between the liquid product and water within the casing. The casing in the interface detecting device or the leak detector casing is completely enclosed except for an opening in the top of the casing for the entry or escape of liquid product into or out of the casing. The apparatus for establishing a clean interface includes a normally closed water inlet/outlet system at the bottom of the casing and a mechanism for opening and closing the water inlet/outlet system.

Abstract: The method for detecing leaks in an above ground storage tank by sensing changes in conductivity along a line intersecting an interface between the liquid product in the tank and water in the tank with a leak detector includes the step of collecting magnetic metal contaminants to prevent magnetizable particles from fouling the sensing of changes of conductivity.

Abstract: A magnetic contaminant collector for collecting magnetizable particles is provided for use in an above ground storage tank and is situated in the tank at the interface between the liquid product in the tank and the water in the tank. A leak detector including a sensor assembly comprising an array of conductivity sensors for sensing conductivity is also situated in the tank. The magnetic contaminant collector is located so as to prevent magnetizable particles from fouling the conductivity sensors of the leak detector.

Abstract: The method for detecting leaks in an above ground storage tank includes the step of first determining the level of water in the tank by establishing, in a container lowered into and resting on the bottom of the tank, a clean interface between water and a liquid hydrocarbon product in the tank which has entered into the container. Preferably the method includes an initial step of inserting a predetermined amount of water into the container before lowering the container into the tank. The method also includes sensing changes in conductivity along a line intersecting an interface between the liquid hydrocarbon product in the tank and water in the tank with a leak detector in a casing and establishing a clean interface in the leak detector to prevent debris at the interface in the tank from fouling the sensing of changes of conductivity.

Abstract: The leak detector is utilized for determining the presence of a leak in an above ground tank of liquid having a lower specific gravity and a lower electrical or thermal conductivity than water. The leak detector includes a device for determining the level of water in the tank and a mechanism for sensing changes in the level of water in the tank over time. A leak detecting system utilizing the leak detector will also include an apparatus for determining the amount and rate of leakage relative to the capacity of the tank and the change of the level of the water in the tank over a selected time period.

Abstract: In using the method for testing for leaks, in an above ground tank of liquid having a lower specific gravity and a lower electrical or thermal conductivity than water, first an amount of water sufficient to cover the bottom of the tank is introduced into the tank after which the level of the water in the tank is determined and changes in the level of the water in the tank over time are sensed. Additionally, the amount and rate of leakage relative to the capacity of the tank and the change in the level of the water of the tank over a selected time period are determined from the given parameters and the change in water level.