Abstract: A method of making a storage tank comprises forming a cylindrical-shaped inner tank with integral support ribs and forming an outer wall comprised of a series of sections which are at least partially separated from the inner tank's walls between each set of support ribs. Each outer wall section is bonded to side walls of adjoining ribs at a distance of less than about 90% of the height of the support ribs such that the ribs protrude from the outer surface of the storage tank system. The inner and outer walls of the system are both strengthened by the common support ribs. Secondary containment is provided by the outer wall. A monitored storage tank system is provided by the use of a leak detection means to monitor the closed space defined by the rib interiors, the outer wall and the storage tank.

Abstract: The present disclosure is directed to a method and apparatus for monitoring leaks from underground storage tanks and the like. One or more wells of specified depth are formed and each well is lined with plastic pipe which is perforated to admit migratory diffused hydrocarbon molecules from the soil into the pipe. A cap closes the upper end of the pipe and supports a cable which holds an absorbent cartridge. The cartridge has a perforate housing and the housing filled with beads of divinylbenzene which serve as a hydrocarbon, hydrophobic absorbent material. A test procedure is also set forth wherein absorbed hydrocarbons from test cartridges are correlated to background levels and the signature of a stored hydrocarbon product.

Abstract: A double walled storage tank system comprises an inner storage tank, a separating material and a jacket formed of a fibrous reinforced resinous material. The separating material has a series of holes extending therethrough to act as molds to receive resinous material. The jacket has an integral structural strength capable of withstanding external load forces normally encountered by underground storage tanks. Secondary containment with leak detection capability is provided.

Abstract: A method is described for enabling leak detection of an underground storage tank surrounded by a water table. The method begins by sealing a test probe in the tank, the test probe having an elongated substantially hollow core with first and second ends, a housing for receiving the second end of the hollow tube and being vented to the fluid product, a low temperature coefficient medium supported in the substantially hollow core of the elongated tube, and a liquid seal supported in the housing between the medium and the fluid product. The method continues by then establishing and maintaining a pressure equilibrium between the hollow core of the test probe and the head space. An inert gas such as nitrogen is then introduced into the head space to overpressurize the head space by an amount sufficient to reestablish a leak at any break in the storage tank despite presence of the water table surrounding the storage tank. Once the tank contents are stabilized, the precision leak test is performed.

Abstract: A method for making a dual wall tank for storing fluids by producing an inner wall for storing the said fluid, positioning a fabric exteriorally against the inner wall, applying a liquid resin exteriorally to the fabric so as to penetrate partially into the fabric, and curing the liquid resin so as to form simultaneously an outer wall for containing any leakage of the fluid from the inner wall and an interstice consisting of an intermediate layer of fabric permeable to any leakage of the fluid through the first wall; and includes the dual wall container formed thereby.

Abstract: In order to accurately conduct a leakage test in a short time, an initial pressure higher than a test pressure is first supplied into a hollow object to be tested. Then, part of the pressure within the object is relieved to decrease the temperature within the object to the ambient temperature so that the pressure within the object can be stabilized at the test pressure. Then, a variation in the pressure within the object is detected to determine whether there is any leakage in the object. In the case where a negative pressure is utilized, an initial pressure lower than the test pressure is first supplied into the object, and then part of the pressure within the object is relieved by introducing the ambient air into the object, to increase the temperature within the object to the ambient temperature so that the pressure within the object can be stabilized at the test pressure. Then, a variation in the pressure within the object is detected to determine whether there is any leakage in the object.

Abstract: A liquid confinement type of leak detection system for a liquid retaining chamber defined by an inner wall of the system. The leak detection system also includes an outer wall in closely spaced adjacent relation to the inner wall to define a normally liquidtight leak detection chamber therebetween, and a porous material disposed between the inner and outer walls so as to be in contact with the inner and outer walls in a manner forming a structural bond therewith. Further, the leak detection system includes sensors associated with the porous material at selected points in the leak detection chamber.

Abstract: A housing, simulating the configuration of a container such as a glass bottle, includes an internal chamber for supporting a center post having an axial bore for receiving a biaxial accelerometer electrically connected to circuitry for detecting and recording the magnitude of the impact force applied externally to the housing. In a method for simulating the impact forces applied to glass bottles as they are conveyed in a bottling operation impact forces are applied at any angle to the housing and are transmitted to the accelerometer. The accelerometer is actuated to generate an output signal expressed in terms of the X and Y vectors of the impact force to the electrical circuitry. The output signal is processed to indicate the magnitude of the applied impact force.

Abstract: Apparatus and an associated method for inspecting a container neck for the desired shape includes an upper body portion having an elongated bore therethrough, and a downwardly projecting lower body portion having a passageway generally aligned with the bore. The lower body portion has an outer surface corresponding to the desired shape of the inner portion of the container neck but of a size corresponding to the minimum permissible inside diameter of the container neck. In one embodiment the lower body portion has at least one vent opening to facilitate improved container neck inspection. Sealing material is provided such that when the container neck is of the desired shape the lower body portion will be received within the neck in such a manner that the passageway will be in sealed communication with the container interior.

Abstract: A liquid tank leakage detection system includes a standpipe and associated measuring pipe together with a sealing connection to the filler pipe of a liquid tank system. A liquid level detector used in cooperation with the measuring pipe includes a float coupled to a measuring beam having one end fixed and the other end coupled to the float. Level changes within the liquid system produce position changes of the float which in turn causes bending or flexing of the beam. A bridge detecting circuit including strain gauges coupled to the flexing beam is operative to provide an output signal indicative of the extent of liquid level changes. A thermocouple is positioned within the liquid tank to provide a temperature compensating signal for use by the measurement system.

Abstract: A pressure vessel for fluids containing hydrogen and subjected to a neutron flux. The vessel comprises an inner sealing layer and an outer load bearing layer. The inner sealing layer is composed of a material having a radiation induced diametral deformation rate higher than that of the outer layer to minimize stresses therein. The outer layer is provided with apertures, and the boundary between the inner and outer layers is non-metallurgical such that any fluid which penetrates the sealing layer will readily pass through the outer layer where it can be detected, by suitable detector before it produces embrittlement of the load bearing layer. The preferred application for the invention is in pressure tubes for a nuclear reactor.

Abstract: A liquid level measuring system having a tubular ultrasonic probe with a length in excess of the depth of liquid to be measured; for vertical insertion into a tank. A transducer inside the tube, at a first distance above the bottom end of probe body, responds transmits a sinusoidal acoustical pulse through the probe to the surface of the liquid. An echo returns from the surface of the liquid to the transducer and provides a sinusoidal echo signal. A receiver responds to the echo signal by providing a start signal corresponding to the transmitter signal crossing a predetermined amplitude in a predetermined direction and by providing a stop signal corresponding to a first selected echo signal crossing a second predetermined reference level in a predetermined direction. The speed of sound in the liquid is measured by measuring the echo time to a calibration rod in the tube at a known distance from the transducer.

Abstract: A fuel leak detector for an aircraft system is shown as comprising a plurality of potential fuel leak sources where leaking fules are routed to a collector through a leak detector associated only with only one of the potential leak sources and the fule leak collector. Each detector permits the flow of leaking fuel into the collector, while at the same time maintaining a visual or other type of indication of the location of the fuel leak. Each detector comprises a small, light weight container which traps up to a predetermined amount of any fluid flowing through it. The level of the trapped fluid is indicated by a float. Fluid in excess of the predetermined amount flows through the container trap and into the collector. The contents of the collector are tested for fuel, and if fuel is detected, the maintenance personnel then search the individual traps for a visual indication of the location of the fuel leak.

Abstract: A tank leak detection system in which a liquid level multiplier is connected to a differential pressure transmitter one side of which may be piped back into the tank to compensate for internal changes in tank pressure. A capillary having a small bore connects the transmitter and the multiplier to reduce temperature effects. Changes in tank temperature may be sensed, i.e., by a long bulb thermometer and either fed to a temperature transmitter to convert temperature change into a single to a computer used to calculate true tank level and output a signal proportional thereto or fed to the level transmitter to compensate for temperature changes.

Abstract: An enviromentally sound, non-contaminating underground liquid large storage tank leak containment, detection and alarm system containing: an impervious, steel reinforced, parallelpiped, non-fibrous concrete tank-containment vault. The vault has a fill pipe, a dispenser pipe, a vent pipe, and a vertical leak detection and pumpout pipe. Readily removable leak detection means are located near the vault floor within the leak detection and pumpout pipe. An electrical alarm is triggered by the leak detection means. The term "parallelpiped" describes the three dimensional vault configuration where the rectangular end walls and side walls, and the lid and floor portions are substantially parallel and each of the interior angles is approximately ninety degrees.

Abstract: An apparatus and a method for collecting in seal containers the gasoline that leaks or spills from service station dispensers or submersible pumps help to reduce the pollution associated with such equipment. The apparatus and the method also provide for returning the collected gasoline to the storage tanks via existing vapor recovery systems.

Abstract: An apparatus for indicating the peak tangential velocity of a swung sporting goods implement such as a tennis racquet, golf club, or baseball bat, comprises a tube having a longitudinal bore. A seismic mass is slideably disposed within the bore of the tube, and a spring operates to pull the seismic mass toward the proximal end of the tube. A reset mass is normally captured at the distal end of the tube but is selectively released to slide within the bore of the tube. A peak velocity indicator is slideably disposed within the bore of the tube between the seismic mass and the reset mass, the peak velocity indicator frictionally engaging the inner walls of the tube such that it is displaceable longitudinally within the bore of the tube by an applied force but maintains its position within the bore of the tube once the applied force is removed.

Abstract: A test probe is described for substantially eliminating measuring inaccuracies in a storage tank leak detection system caused by temperature-induced volumetric changes in the stored fluid product. The apparatus comprises an elongated tube, formed of a low temperature coefficient material, supported in the storage tank and having first and second ends and a substantially hollow core. A housing is attached to the second end of the elongated tube and is vented to the fluid product such that a portion of the fluid product enters the housing. An inner tube is located within the elongated tube and has an opening connected to the housing. The inner tube is preferably supported within an outer tube and the inner and outer tubes are separated by an evacuated space to provide thermal isolation of the inner tube from the elongated tube. A low temperature coefficient medium is then supported in the inner tube.

Abstract: A liquid leak detector for above-ground tanks includes an upright standpipe connected to the tank so that the standpipe can be filled with liquid from the tank to the same level as the liquid in the tank. A pressure transducer is connected between the bottom of the tank and the bottom of the standpipe to measure the difference in pressure of the liquids in the tank and standpipe. Any change in the liquid pressure at the bottom of the tank as a result of leakage from the tank will change the pressure differential on the pressure transducer. This changes the output of the transducer which can be recorded to indicate leakage from the tank.

Abstract: Apparatus for and method of testing whether a tank completely filled with liquid is leaking comprising a liquid containing standpipe in fluid communication with a tank to be tested, and mechanism for maintaining a substantially constant head pressure on the bottom of a tank being tested as the volume of liquid from the tank tends to expand or contract.

Abstract: This invention is directed to detecting and locating leaks in geomembrane liners used to contain liquid or liquid-solid materials, such as in waste landfills and liquid impoundments. An array of electric or magnetic field detectors is placed on one side of the liner. The detector array is on a plane generally parallel to the liner, and the location of each detector is known. A voltage is impressed across the liner. When a leak occurs in the liner, a current flows through the leak, creating an electric field and a magnetic field around the leak. The existence of the electric or magnetic field is detected by the detector array, which indicates a leak. The leak is located with orthogonal measurements from selected detectors, and these measurements are used to geometrically locate the leak.

Abstract: Apparatus for detection leakage of hydrocarbon-containing liquid, such as gasoline, from a generally cylindrical tank. The apparatus includes an elongate displacer having a vertical axis and extending substantially the full height of the liquid in the tank. The displacer has an upper end and a lower end with the displacer lower end terminating closely adjacent but spaced from the bottom of the tank. The displacer is made of a material having a coefficient of linear expansion of less than 20.times.10.sup.-6 inches per inch per degree centigrade. Furthermore, the displacer is substantially symmetrical about about any plane through its vertical axis and it has an outer surface which is a surface of revolution. The displacer has a varying diameter along its length corresponding to the horizontal surface area of the tank at the same height inside of the tank. The apparatus further includes a sensor for providing an indication of the weight of the displacer disposed in the liquid.

Abstract: A computerized leak tester system for rapidly testing a work piece for fluid leaks comprising a continuously regulated pressure supply, a coupler for connecting the pressure supply to a work piece through a valve such that the work piece is both pressurized and tested for leaks through the valve. A differential pressure transducer is connected across the valve for producing a signal in response to a differential pressure detected across the valve. A signal conversion means is provided for receiving the signal from the differential pressure transducer and for converting it into a computer readable signal. A computer is provided for receiving the computer readable signal which represents differential pressure value and for converting the differential pressure valve into a current flow rate value. Circuitry is provided in the computer for comparing the current flow rate to a predetermined flow rate value representing a maximum allowable leak rate.

Abstract: A double containment and leak detection apparatus including a tank, having a bottom and a surrounding shell, with a containment baffle means above the bottom and a leak detection means in a containment space between the containment baffle means and the tank bottom. The containment baffle means includes a baffle plate sealingly joined to the interior of the shell to form a sealed containment space between the containment baffle and the bottom. The leak detection means is installed in the containment space to detect the presence of stored material held in the tank in the event such material leaks into the containment space. The leak detection means is connected, through a leak-proof access, to means external to the tank for responding to such leaks of stored material so detected inside the containment space.

Abstract: An elongate safety conduit or trench for receiving chemical liquids, having first and second preassembled conduit elements, the first located and retained within the second. A space is between the two at the bottom for collecting liquid that may leak through the first. A seal along the length of the conduit between the two elements inhibits entry of liquid between the two.

Abstract: A reservoir for leak detecting fluid for a tank is disclosed. A reservoir is used with a double wall glass fiber reinforced plastic tank where the tank has an inner wall, an outer wall, and annular space between the inner and outer walls for receiving a leak detecting fluid and an enclosed space within the inner wall for the storage of a liquid. An opening is provided in the outer wall of the tank and the opening is in communication with the annular space between the inner and outer walls. A one-piece reinforced plastic reservoir for leak detecting fluid is positioned on the tank. The reservoir has a sidewall and an end wall extending across one end of the sidewall. The sidewall is secured to the outer wall of the tank with the interior of the reservoir being in alignment with the opening in the outer wall of the tank.

Abstract: The method of preventing leakage from, or leakage into, an underground fuel storage tank comprising the steps of: positioning a flexible liner adjacent the interior surface of the tank so as to create a flow path between the liner and the tank towards a leak monitoring cable; and applying an epoxy material to the interior surface of the liner to maintain the liner in position.

Abstract: A system for containing and detecting the leakage of liquid from a receiver, such as a tank or conduit, includes absorbent material which is capable of absorbing liquid which leaks from the receiver. The absorbent material is enclosed by casing material which is dissolvable by the liquid in the receiver. Upon the occurrence of a leak, the liquid which leaks from the receiver dissolves the casing material to expose the absorbent material so that it can absorb the leaking liquid. A detector provides an output signal in response to leakage of liquid from the receiver. The detector may include a pair of electrodes which are electrically insulated from each other by material which is also dissolved by liquid which leaks from the receiver. When the insulating material between the electrodes is dissolved, current is conducted between the electrodes to provide the output signal.

Abstract: A system for detecting leaks in a tank, or the like, comprising an excavation basin including a periphery and defining a generally saucer-like formation with a basin surface with slopes from the periphery. A tank supported by the excavation basin. The tank as a permeation barrier extending from the periphery of the basin excavation and is supported by and conforms to the basin surface of the saucer-like formation. A corrosion curtain is integrally bound to the permeation barrier and defines an upright wall of the tank. Particulate matter is supported by the permeation barrier, and a liquid-impervious liner continuously extends from the top of and down the corrosion curtain upright side wall and across the top of the particulate matter that is being supported by the permeation barrier. An improved liquid leakage receiver is positioned in the particulate matter.

Abstract: A protective lining arrangement, which is intended for use in industrial halls, especially in large-area storage halls, and, on the one hand, is to be capable of being loaded to a high degree by vehicles, machines and stored goods while, on the other hand, is to provide excellent protection against undesirable seepage of hazardous liquid substances into the ground, consists of a plurality of protective lining components which are connected to one another by welded joints. Each of such protective lining components includes an upper plate, a lower plate, and a distancing layer of expanded metal which is interposed between the upper and lower plates and keeps them apart by a predetermined distance, while simultaneously providing between the two plates a gap space having a width corresponding to the predetermined distance. The gap spaces of the protective lining components can be evacuated and are connected via a measuring conduit to a leakage monitoring device.

Abstract: A device for testing a package having, a device for passing a fluid inside the package, and a device for selectively controlling the rate of pressure increase inside the package by the passing device.

Abstract: An improved apparatus for substantially eliminating measuring inaccuracies in a storage tank leak detection system caused by temperature-induced volumetric changes in the stored fluid product is described. The apparatus comprises an alongated tube supported in the storage tank and having first and second ends and a substantially hollow core. The apparatus also includes a housing supported in the storage tank for receiving the second end of the elongated tube. The housing is vented to the fluid product such that a portion of the fluid product enters the housing. According to the invention, a medium is supported in the substantially hollow core of the elongated tube, the medium having a temperature coefficient substantially lower than the temperature coefficient of the fluid product.

Abstract: A method of making a jacketed storage tank comprises applying a layer of wax over a rigid inner storage tank, applying fibrous reinforcing material and resinous material onto the wax, and then curing. The wax is subsequently melted and removed to create a continuous space. The resultant jacket is structurally independent from the storage tank, yet is in such close proximity thereto that the resultant jacketed storage tank has an integral structural strength capable of withstanding external load forces normally encountered by underground storage tanks. Secondary containment is provided by the jacket.

Abstract: A storage tank system especially useful for storing liquid gasoline comprises a rigid inner tank, access lines extending through the tank, a sleeve attached to the rigid inner tank and encompassing the access lines, and a jacket encasing the tank and at least part of the sleeve. A leak detector is associated with the closed space between the inner tank and jacket to detect leaks. The system results in a storage facility which is not likely to lose its stored liquid to the environment due to slow leak or a sudden large leak by providing total containment capability.

Abstract: A jig for leak check capable of safely carrying out leak check of a hollow checked object using pressurized gas without damaging it irrespective of its wall thickness. The jig includes a jig body constituted by two joinable members so as to define an inner space therein. In the jig body is provided a closed chamber in which a checked object is hermetically received for leak check. The closed chamber may be formed by the inner space of the jib member itself. Alternatively, it may be formed by cooperation between a depression of a flexible and stretchable air bag arranged in the inner space of the jig body and a part of an inner surface of the jig body. The closed chamber is provided on at least a part of its surface with a leak lead-out element which may comprise a plurality of fine grooves formed in a mesh-like pattern on the surface of the closed chamber or a lining made of an air-permeable material and applied on the inner surface of the closed chamber.

Abstract: The present invention provides apparatus and an associated method for testing containers for volume and leaks by employing a pump which provides rapid pressurized pulses simultaneously to a container being tested and a standard volume which may be a container. Acoustic impedance materials are interposed between the pump and the two containers to isolate the containers from each other. A differential pressure monitor is interposed between the two containers to provide output to electronic processing apparatus which may serve to either determine (a) solely if a leak exists or (b) in the alternative if no leak exists to determine whether the desired volume is present within the container.

Abstract: In order to improve existent methods for measuring the sealing of tanks (1), the temperature (.theta..sub.1) of the tank is measured when taking up a magnitude relative to the pressure (p) representative of a leak. A predetermined magnitude relative to a limit pressure (p.sub.G) to decide whether a tank fulfils the required sealing conditions at a temperature (.theta..sub.2) is calculated for a measurement temperature (.theta..sub.1); the actual pressure value and the limit or ultimate pressure value at this measurement temperature (.theta..sub.1) are then compared. Thereby, pressure variations due to temperature variations are taken into account.

Abstract: Method and apparatus are described for detecting the leakage of fluid under storage tanks. A number of parallel perforated test conduits are placed under the tank which is to be tested for leaks. A vacuum is placed on the test conduits to remove gas and liquid, if any, from the soil beneath the tank. If no gas or liquid is found it indicates that there is no leak. If gas or liquid is found, small test areas are isolated under the tank. The isolated areas may be placed under vacuum or pressure so gas and/or liquid can flow therethrough under pressure so that analysis of the flow in or flow out of the test conduit can be made to determine if that isolated area has leakage. The isolated areas can be changed until the isolated area with the leak is found.

Abstract: A liquid leak detector for above-ground tanks includes an upright standpipe connected to the tank so that the standpipe can be filled with liquid from the tank to the same level as the liquid in the tank. A pressure transducer is connected between the bottom of the tank and the bottom of the standpipe to measure the difference in pressure of the liquids in the tanks and standpipe. Any change in the liquid pressure at the bottom of the tank as a result of leakage from the tank will change the pressure differential on the pressure transducer. This changes the output of the transducer which can be recorded to indicate leakage from the tank.

Abstract: An evacuation unit for testing the fluid tightness of a closed fluid system, filling the system with system fluid, and/or purging the system fluid of entrained gas. The evacuation unit includes a source of system fluid, an air operated venturi vacuum pump, a hose for releasable and sealable connection to an access port of the closed fluid system, and a three way valve for selected positioning between a first position communicating the vacuum pump with the flexible hose system to produce a vacuum in the system, a second position isolating the flexible hose and system to test for fluid tightness, and a third position communicating the system fluid source with the flexible hose and system for filling the system through the access port with system fluid. Multiple reservoirs may be employed for filling the system with multiple fluids through the use of a reservoir sequence valve. The sequence valve permits filling the system by drawing liquid from multiple sources in a predetermined sequence.

Abstract: A system for detecting leaks in hazardous liquid tanks, particularly underground gasoline tanks at service stations. The tank is filled incompletely to leave a space in the tank which is then filled with a gas under pressure. A reference tank is disposed within this space and continuous streams of gas are forced into the liquid in the reference tank and the liquid in the tank being measured. Resistance to gas introduction in the reference tank is compared with the resistance to gas introduction in the gasoline tank and monitored during a test period to note any differential variation which would indicate a leak in the tank.

Abstract: Changes in the tide effects at a given location are measured by monitoring the respective levels of a measuring liquid in two containers which are in fluid communication with one another. The liquid levels are measured by suitable transducers including floats, and result in electronic signals indicative of the respective positions of the floats. A difference between the two signals is either computed or obtained from a differential amplifier into which the signals indicative of the respective float positions are inputted. A change in the difference between the float positions measures a change in the tidal effects at the location. The change in tidal effects is advantageously measured in conjunction with measuring leakage of liquid from liquid storage tanks, such as fuel storage tanks of filling stations, where tide effects occur and must be taken into account.

Abstract: A method of making a storage tank comprises forming a cylindrical-shaped inner tank with support ribs and forming an outer wall comprised of a series of sections which are at least partially separated from the inner tank's walls between each set of support ribs. Each outer wall section is bonded to the side walls at a distance of less than about 90% of the height of the support ribs such that the ribs protrude from the outer surface of the storage tank system. The inner and outer walls of the system are both strengthened by the common support ribs. Secondary containment is provided by the outer wall. A monitored storage tank system is provided by the use of the leak detection means to monitor the closed space defined by the rib interiors, the outer wall and the storage tank.

Abstract: A microprocessor based system for detecting leaks from underground gasoline storage tanks and the product lines through which the gasoline is pumped to above ground dispensers. Hydrocarbon sensitive probes spaced around the tank in monitoring wells detect gasoline leakage from the tank. Each probe can be independently programmed as to the threshold hydrocarbon concentration considered to be indicative of a leak. Pressure transducers sense the product line pressure and distinguish thermally induced contraction from true leaks by comparing the time required for a preselected pressure drop to occur during successive cycles. A time comparison is also used to detect the presence of excessive air in the product line. An alarm condition sensed by either type of sensor generates audible and visible alarm signals and automatically dials a programmed telephone number. The alarm times and dates are stored in memory and may be called up on the display screen.

Abstract: An apparatus for detecting volumetric leaks includes an arrangement for measuring linear displacement of a surface, including the surface of a liquid. The arrangement includes a beam generator for directing a collimated or coherent beam of energy onto a surface, a non-planar mirror to receive the beam as it reflects from the surface, and a receptor for receiving the beam as it is reflected from the mirror. Changes in position of a footprint of the beam on the receptor correlate to changes in displacement of the surface and accordingly, volumetric changes of a contained liquid. The non-planar mirror amplifies or exaggerates the changes in the position of the footprint relative to linear displacement of the surface so as to enable detection of small displacements of the surface.

Abstract: A wand having a length of flexible hose extending therefrom is inserted within an underground fluid filled storage tank. Through actuation of a propulsion system, the wand is directed to a suspected vapor pocket within the tank and temporarily retained in place by floatation. An evacuating pump draws in the vapor through inlets at the extremity of the wand and through the trailing hose to reduce or eliminate the vapor pocket within the tank. Upon elimination of the vapor pocket to a practical extent, the hose and attached wand are withdrawn from the tank.

Abstract: A method of making a jacketed storage tank comprises applying an open-cell synthetic foam over a rigid inner storage tank, applying a layer of fibrous reinforcing material on the separating agent, and applying a resinous material. The synthetic foam is at least partly sealed to prevent excessive resinous material penetration so as to maintain the continuous open-cell nature of the foam. The resultant jacket is structurally independent from the storage tank, yet is in such close proximity thereto that the resultant jacketed storage tank has an integral structural strength capable of withstanding external load forces normally encountered by underground storage tanks. Secondary containment with leak detection capability is provided.

Abstract: A leak detection system for detecting the leakage of fluids from storage tanks uses a reference container, such as a standpipe, having its bottom adjacent the level of the bottom of the tank, which is initialized to the same hydrostatic head pressure as the tank, and then closed off. The differential pressure between the hydrostatic head pressures of the standpipe and the tank is monitored over time in an externally mounted differential pressure gauge in order to detect the leakage of fluid from the storage tank. Shut off of valves are provided in a tank pressure pipe and a reference pressure pipe to isolate both sides of the differential pressure gauge. The very high sensitivity of available differential pressure gauges allows the detection of very small leaks and very low leakage rates. A leak detection system of unitary construction may be provided in which the standpipe is provided with an equalizing valve so that the system may be installed through a single hole in the top of a liquid storage tank.

Abstract: A method and apparatus are disclosed for detecting leaks in a liquid-containing tank. The method and apparatus employ an internal reference cell immersed in the liquid in the tank which contains a volume of the liquid isolated from flow communication with the liquid in the tank while having a surface which is exposed to the ambient conditions above the surface of the liquid in the tank. The level of the fluid in the tank and in the reference cell are monitored over a period of time. Level changes in the tank which do not correspond to level changes due to the temperature and evaporative effects observed in the reference cell are indicative of a leak in the tank.

Abstract: A method and apparatus for detecting leaks in a test chamber utilizing pressurization of the chamber with a gas, compares the rate of change of the gas pressure in the test chamber with the rate of change of the temperature of that chamber with the difference in such rates of change being read as a function of test chamber leakage.