Abstract: A method of compensating for temperature variations in testing part cavities for leaks by placing a fluid pressure source in communication with the cavity and measuring the flow rate to the cavity to determine the rate of any leakage. The method establishes a temperature compensation function by measuring the shift in flow rates resulting from changes in temperature of a sample test part, which temperature compensation function allows correction of the flow rates during subsequent testing according to the sensed temperature of the test part. Flow rates are measured at two differing temperatures to determine the temperature compensation function by linear regression, since the flow rate shift with temperature varies substantially linearly.

Abstract: A storage tank system especially useful for storing liquid gasoline comprises a rigid outer tank fitted with a bladder and an analyzer. The system results in a storage facility which is less likely to lose its stored liquid to the environment due to a slow leak or a sudden large leak such as is possible with an earthquake.

Abstract: A storage tank system especially useful for storing liquid gasoline comprises a rigid inner tank encased by a flexible outer jacket with a leak detecting means associated with the closed space between the inner tank and jacket. The system results in a storage facility which is less likely to lose its stored liquid to the environment due to a slow leak or a sudden large leak such as is possible with an earthquake.

Abstract: An improved method of measuring leak rates by placing a source of fluid pressure in communication with a cavity being tested, and measuring the flow rate to the cavity after a predetermined time to determine the leak rate from the cavity. The improved method achieves a determination of the leak rate in a shorter time than that required to establish steady state flow conditions between the pressure source and the test piece cavity. The improved method measures the flow rate to the test piece cavity at a much earlier time after pressurization of the cavity than normally required to establish such steady state conditions, and applies a previously generated calibration function based on a linear correspondence between the measured flow rates and the steady state flow rates.

Abstract: A seal of composite construction for leak testing two piece "drawn" aluminum and steel cans and three piece welded steel cans. The novel can is formed of elastomeric materials of differing hardness which are molded together to form a single, integrally formed unit. More specifically, a core formed of a soft material is disposed in sandwiched relation to working surfaces formed of a harder material so that the beneficial and detrimental characteristics of such materials are synergistically maximized and minimized, respectively. In operation, the seal is axially displaced into and out of sealing registration with the open, flanged ends of cylinders to be used as portable containers. The hard working surfaces of the seal, or pad, resist abrasion and detect microsplits, thereby overcoming the limitations of conventional soft seals, while the soft core provides the needed resiliency, thereby overcoming the limitations of conventional hard seals.

Abstract: Leakage from a gasoline storage tank or other receptacle is detected by differentiating the output from a liquid-level monitoring transmitter with stepped voltage output and applying the differentiated transmitter signal through an amplifier to a latch controlled relay for activating an alarm. An interlock circuit is provided for deenergizing the detector part of the system whenever the contents of the tank is being altered intentionally.

Abstract: A leak detector includes an air tight chamber having three openings therein. The first opening is connected to a source of compressed air or other gas. The second opening is provided to the fill pipe of a tank to be tested for leaks. The third opening is connected to a slope tube which is calibrated to detect changes in the height of a column of liquid in a slope tube. When pressure is applied to the chamber from the source of compressed air, bubbles are forced into the fill pipe. A corresponding pressure creates and maintains a column of liquid in the slope tube. Changes in the level of the fluid in the tank due to leakage result in a corresponding change in the level of fluid in the slope tube.

Abstract: An indicating shipping accelerometer having a transparent tube within which an inertial mass moves indicators relative to a scale affixed to the transparent tube to give an indication of the maximum shock incurred in either direction of its longitudinal axis. Springs on either side of the inertial mass maintain the inertial mass in its initial position. The unit may be reset for reuse by inserting a wire through the endcaps and repositioning the indicators.

Abstract: A method and apparatus for detecting perforations in an underground fuel storage tank, employs the creation of a partial vacuum in the tank and a pressure difference across the tank wall, to cause air to pass through the perforation, and a hydrophone to sense the acoustic waves produced by the formation of air bubbles in the fuel. The acoustic waves of the bubbles caused by the air passage are sensed by a hydrophone and processed to provide an electrical signal indicative of the presence of the perforation. A water level sensor is also used to detect the level of water beneath hydrocarbon fuel in the tank. The method and apparatus can also be used with above ground fuel storage tanks and other types of above and below ground storage tanks.

Abstract: An apparatus for detecting small changes in the location of a float, has, in combination, a signal generator for emitting a signal having a characteristic, a detector for detecting a modulated signal by producing a response signal directly related to the characteristic, a support for positioning the signal generator and the detector, and a float weighted to float at a desired depth in a selected liquid. Also included are a reservoir for holding a measuring medium, a plug for preventing condensation of vapors within the float, with the float movably connectable to the support, and the detector and the signal generator fixedly connectable to the support so that the signal when emitted by the signal generator will have the characteristic of the signal modulated by the measuring medium by an amount which varies with changes in location of the float to produce a modulated signal.

Abstract: A leak detector comprising a housing having an axis on first and second compartments spaced along the axis and hermetically separated by a partition, the first compartment being closed to comprise a pressure envelope which is in communication with an evacuated space to be monitored for leakage, an ionization cell in the first compartment providing an electrical current determined by gas in that compartment, hermetically sealed feed-through for enabling an electrical connection with the gauge, to the partition from the second compartment, an apparatus in the second compartment performing a control function in accordance with the current supplied by the cell.

Abstract: A method of inspecting storage tanks for leaks by means of pressure decrease and increase in the tanks, in which a part of a liquid 6 stored in a tank 1 is discharged to put the tank 1 under vacuum and variations in the pressure in the tank 1 with time are checked, the pressure in the tank 1 is thereafter increased to the level of the atmospheric pressure, and then the liquid which was discharged from the tank is poured back thereinto to put the tank under pressure and variations in the pressure in the tank with time are checked. The method is done by an apparatus designed for inspecting storage tanks for leaks by means of pressure decrease and increase in the tanks, having an air pipe (2), a measuring pipe (3), a liquid feed pipe (4), a liquid suction pipe (5) and an air-tight container (7), which are communicated with a tank (1) to be inspected, a pressure regulator pump (8) connected to the air-tight container (7), and a manometer (11) and a recording air gauge (10) connected to the measuring pipe (3).

Abstract: A method and device for leak testing vessels such as fuel cells or tanks which are large enough for a person to move around within holding a small hand held ball or balloon type device which is provided with a large aperture. In leak testing a vessel, the aperture portion of the device is pressed against the inside wall of the vessel with sufficient pressure to form an airtight seal between the inside of the device and the wall. While maintaining the airtight seal, the device is moved over the full inside surface of the cell. If there is a hole in the cell, the device which is very compliant will tend to collapse as it passes over the hole due to a resilient pressure drop created by the hole allowing the air to escape from the device to the atmosphere.

Abstract: A method of testing bottoms of large storage tanks. It involves sealing the outer edges of the bottom plate against gas leakage, followed by feeding a halogen gas to the under side of the bottom plate. Then the top of the bottom plate inside the tank is scanned manually, using a hand-held halogen detector in order to detect any leaks.

Abstract: A system and method for repair of leaking storage tanks containing fluids which contaminate ground water has been devised requiring reduced funding which will make it economically feasible for repair of all old tanks suspected of being potential leakers, thereby protecting the public and environment from future severe hazards.All internal appurtenances are removed from the tank before it is gas freed and fitted with a new combination manway and appurtenances access. All tank openings originally utilized by appurtenances are plugged liquid tight except for the tank vent system. A flexible fluid tight containment means is formed to the tank interior shape and contains an opening edge which is assembled as a fluid tight gasket seal between the flange cover of the new access. All internal appurtenances are relocated to extend through the new access.

Abstract: This invention provides a method for detecting loss by leakage of liquid from a liquid-containing vessel by employing a submersible diaphragm-type pressure transducer having an integral operational amplifier in an appropriate electrical connection with a suitable power supply and digital volt meter. The method comprises steps of placing the transducer into the vessel beneath the surface of the liquid, energizing the operational amplifier to obtain an initial electrical output, recording the initial electrical output with a digital volt meter, adjusting the liquid volume of the vessel by a predetermined amount, (i.e.

Abstract: The invention provides a system for the detection of leaks in the primary barrier (150), the secondary barrier (130), and the inner hull (110) of the primary and secondary insulation spaces (140 and 120) of a cryogenic cargo tank (10) carrying liquified natural gas in a transport ship (20) wherein an inert gas is maintained at a first predetermined pressure (P.sub.NP) in the primary insulation space (140) which is less than the pressure of the cargo gas (P.sub.CH.sbsb.2) and wherein the inert gas is maintained at a second predetermined pressure (P.sub.NS) in the secondary insulation space (120) so that the second predetermined pressure (P.sub.S) is less than the first predetermined pressure (P.sub.NP) and is also less than atmospheric pressure (P.sub.O). A gas sensor (930) is placed in the primary insulation space (140) to detect any leaks in the primary barrier (150) and a sensor (940) is placed in the secondary insulation space (120) to detect the presence of any oxygen due to a leak in the hull (110).

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: The monitor employs a sensing piston whose position is balanced by offsetting the pressure to be monitored on one side of the piston by a reference pressure of approximately equal magnitude on the other side of the piston. A balance valve on the sensing piston controls the rate of flow of the reference gas from a first chamber bounded on one side by the sensing piston, into a second chamber bounded on one side by a signal piston having a striker whose surface is positioned proximate to the outlet of a gas jet tube. The gas jet tube is connected to a sensing gas pressure source and pressure detector and will produce a pneumatic signal when the striker surface of the signal piston blocks the outlet of the jet tube.

Abstract: A portable air-operated apparatus for cleaning, flushing, and filling a liquid cooling system of an internal combustion engine. The apparatus has an air-operated reciprocating piston pump assembly operable to agitate or sequentially move liquid in opposite directions and pump liquid into the cooling system. The pump assembly delivers the liquid to a manifold connected to an input hose coupled to the liquid cooling system. A control valve connected to the manifold is operable to direct an external source of liquid under pressure to the manifold or connect a reservoir carried by the apparatus to the manifold. The manifold has a check valve for controlling one-way forward flow of liquid from the pump to the input hose. A by-pass hose connects the control valve and manifold to by-pass the check valve to allow reverse flow of liquid in the input hose back to the pump assembly so that the pump assembly will effect a sequential forward and reverse flow of liquid in the cooling system.

Abstract: The invention relates to tanks for the storage of liquid and has particular application to the land storage of liquefied gas at low temperature at or above atmospheric pressure. Thus, the invention provides a storage tank of the kind in which the walls are formed by a multiplicity of connected, parallel, part-cylindrical lobes presenting outwardly convex arcuate surfaces, which is characterized in that the side and end walls thereof are provided by a single tier of connected lobes, in that said lobes extend in one common direction over the tank, in that the end walls of the tank comprise part-spherical knuckles closing off the ends of the part-cylindrical lobes, and in that a separating plate is provided at each lobe connection to strengthen the tank against internal pressure and to divide it into separate storage compartments.

Abstract: A leak testing device capable of detecting and measuring gas and water leakage in valves and other parts of pressurized pneumatic and hydraulic systems is disclosed. Gas from a pressurized source is injected into the apparatus of the device and is adjusted to the desired pressure. The flow of pressurized gas is routed into either the gas test section or the water test section of the device. The test media is then routed through the proper range flow meter of the device and then through tubing into the apparatus or system to be tested for leakage. The amount of leakage will be equal to and can be measured by the reading on the flow meter instrumentation.

Abstract: A device is disclosed for providing a non-resettable visual indication of a shock above a predetermined value which is sustained by an object carrying the device, comprising a dome-like housing, at least part of which is transparent; a flange means secured to and extending radially outward from the dome-like housing; a plate-like biasing means secured to the dome-like housing, the plate-like biasing means and the interior surface of the top portion of the dome-like housing being spaced apart and defining a chamber therein; and an indicating body within the chamber positioned between the biasing means and the interior surface of the top portion of the housing. Prior to being subjected to a force above the predetermined value, the indicating body is maintained in a first position and when subjected to a force above the predetermined value is irreversibly released to a second position.

Abstract: Improved method and apparatus for indicating losses of stored liquid materials or penetration of liquid in liquid storage tanks, in connection with a liquid meter. The level change is automatically measured by means of a level meter as a function of time intervals, and a level change not caused by removal or filling under normal operation conditions is indicated as a loss of stored material (such as e.g. due to theft or leaks) or as a penetration of liquid (such as e.g. ground water).

Abstract: This invention relates to an improved apparatus for effecting the high speed testing of hollow articles or containers for leakage. The apparatus includes a normally closed charge valve and a normally open test valve connected in series between a regulated source of pressurized air and the container. A fluidic start signal sets a first fluidic flip flop device to actuate the charge valve to supply pressurized air to the container and energize a first fluid time delay unit which determines the time that the container is to be filled with air. When the first time delay unit times out, it actuates the test valve to connect the container through a flow meter to a test source of pressurized air to measure the flow rate through the container in the event that any leakage is occuring. The output from the first time delay unit also starts a second fluid time delay unit which determines the test period.

Abstract: A transducer has a chamber containing a substance having a monitorable physical and/or chemical property, for example electrical conductivity, which property changes in correspondence with a change in an external influence, for example, temperature. In one embodiment, the chamber is of elongate form and changes in said monitorable property in any part of the substance along the length of the chamber are monitored by a detection means. In a further embodiment the substance is arranged to undergo an abrupt change in the said property thereof, for example, due to a phase change in the said substance, in response to a predetermined change in the external influence, and detection means is provided to detect such abrupt change.

Abstract: The disclosure relates to an improved integrating acceleration switch of the type having a mass suspended within a fluid filled chamber, with the motion of the mass initially opposed by a spring and subsequently not so opposed.

Abstract: A smoke generator is adapted to be used with other apparatus for testing the peripheral seal integrity of a package. The smoke generator heats a fuel within a chamber and then aspirates smoke into a conduit through which fluid is flowing. The apparatus includes additional conduits operatively arranged to selectively flush the chamber of ash and other accumulated particulate material.

Abstract: A method of high sensitivity for measuring leakage of liquid from a storage tank which comprises introducing a sensor into the liquid in the tank, the sensor being coupled to means for sensing displacement of mass, measuring the displacement over a known period of time and calculating the leakage rate. The sensor is designed to compensate for evaporative losses and temperature changes.

Abstract: A method and system for dispersing oil in the event of an oil leak into a body of water from an oil tanker or an oil drilling platform. There is provided structure for detecting the existence of a leak from a container of oil generally surrounded by a body of water into which the oil is leaking; structure for storing an oil dispersant at the site of the leak; and structure responsive to the occurrence of the leak, for automatically causing the dispersant to be released from the containment structure into the leaking oil. In an oil tanker, the system and method may be implemented by providing structure for detecting a leak in the oil tank wall, suspending a container of dispersant inside the oil tank, and providing structure for rupturing the dispersant container in response to the detection of a leak so that dispersant is caused to mix with the oil in the tank before the oil leaks therefrom.

Abstract: An evacuated article-containing package assembly with a vacuum integrity indicator comprises an air-impervious package having an access opening and having at least a flexible portion. An article is included inside the package. A member is included inside the package which is compressible under the influence of pressure less than atmospheric pressure. A closure seal is on the package for sealing the access opening, with the sealed package being air-evacuated. The compressible member is adapted to expand against the flexible portion of the package to outwardly expand the flexible portion if the pressure inside the package equalizes with the pressure outside the package. When this occurs, the expanded flexible portion serves as a visual indicator that there is no vacuum condition inside the package.

Abstract: A self-purging fluid pressure adapter is disclosed which is connected between a fluid test pressure source, a fluid pressure gauge, and a fluid container undergoing a pressure test. The adapter rapidly purges fluid pressure from the pressure gauge when the container is disconnected from the adapter so as to quickly prepare the gauge for testing a next container on a conveyor belt. Two embodiments of the adapter are disclosed, the first operating on the jet pump principle and the second operating on the Venturi tube principle. In both embodiments the adapter includes a fluid pressure inlet chamber connected to the fluid test pressure source and a fluid pressure outlet chamber which is selectively connected to either the container under test or to an ambient fluid pressure.

Abstract: A crown release pressure tester for testing the pressure that is required for a crown carried on a container to fail or if the crown is leaking. The device includes an elongated housing which has a bore extending therethrough. The top portion of the container which has the crown that is to be tested threaded thereon is severed from the container and secured to the top of the housing in axial alignment with the bore. A piston threadably carried in the bore is rotated to increase the pressure imparted through liquid and compressed air until the crown releases from the top of the container. The pressure that the crown releases is recorded on a pressure gauge.

Abstract: A device is provided for testing the integrity of each container in a conveyed sequence of containers by individually applying pressure internally of each, sensing that pressure and generating a signal having a magnitude corresponding to the value of that pressure, comparing that signal magnitude to a selected threshold signal value, providing an output control signal indicative of the achievement of that signal magnitude and setting an enablement device in one of two states corresponding to the presence and absence, respectively, of that output control signal. One of those states corresponds to an unacceptable container condition and the other to an acceptable container condition. If the unacceptable container condition or reject state exists, a reject cycle is enabled over at least an enabling duration sufficient to clear the container or broken portion thereof from the position it occupies in the sequence.

Abstract: A tester for testing the physical characteristics of bottles such as the degree of stretch of a plastic bottle and the pressure required for rupturing a glass bottle. The apparatus includes an elongated cylinder having a bore extending therethrough. A piston is threadably carried within the bore so that when the lower end of the cylinder is secured to the top portion of a bottle, the piston is in axial alignment with the bottle. Upon feeding the piston into the bottle filled with an incompressible fluid, pressure is exerted on the interior of the bottle stretching or exploding the bottle depending on the test being performed.

Abstract: A sensor for measuring leakage from a liquid containing tank comprises a main body portion suspended from a balance arm or other mass displacement detector and has a liquid holding portion in the main body. The cross-sectional area of the liquid holding portion is essentially equal to the cross-sectional area of the main body portion in contact with the liquid in the tank. This arrangement enables evaporation losses to be compensated.

Abstract: A device for detecting a hard landing of an aircraft. The aircraft is equipped with a detector for determining the vertical acceleration produced by the impact of the airplane with the ground. The device is equipped with a threshold trigger for indicating when acceleration exceeds a predetermined level corresponding to a hard landing.

Abstract: A method and apparatus for testing for leaks in a test item which has a temperature different from ambient temperature in which the test item is sealed at atmospheric pressure and the pressure of the sealed air in the test item is measured. The rate of change of the pressure of the sealing air due to the non-ambient temperature of the test item is calculated for providing a temperature correction signal proportional to the temperature of the test item and the temperature correction signal is stored. The test item is then subjected to a leak test pressure, any change in the pressure of the pressurized test item is measured and the stored correction signal is applied to the pressure measurement for determining the extent of any leak in the test item while compensating for the temperature of the test item.

Abstract: A baseball bat has its handle, shaped to be grasped by the hand of a user, extending on into an enlarged hitting portion that continues away from the handle. Included in that hitting portion is a velocity meter situated in a cavity that extends longitudinally inward toward the handle from the outer end. A plunger is slidably received within that cavity and is resiliently held in place. Also included is an indicator which informs as to the amount of movement of the plunger outwardly from within the cavity as a result of the swinging of the bat by the user.

Abstract: A fluorescent leak detection composition is provided comprising water, a nonionic surfactant having an HLB value of about 12 to about 14 in an amount effective to produce stable bubbling of the composition for a time sufficient to enable detection of a leak in a container when the composition is applied to the surface thereof, about 0.025 to about 1.0 weight percent sodium fluorescein and a semisynthetic cellulose thickening agent in an amount effective to provide the composition with a viscosity of about 75 to about 125 cps at 20.degree. C. Preferably, an antifreeze agent is added in an amount effective to retard freezing of the composition for at least 5 minutes when the composition is applied to a cold surface, such as refrigeration pipes.

Abstract: Upon impact, a ball is released and radially displaced into an annular space of decreasing thickness. Simultaneously, the ball releases a fluid to an absorbent material. The direction and distance of displacement indicate the direction and magnitude of the impact, and the subsequent migration of the fluid in the absorbent material indicates the elapsed time since the impact.

Abstract: A seismic instrument or accelerograph for recording the spectra of strong earthquake shocks or the like, having a series of mechanically-resonant recording units which trace or "scratch" linear records with styli on metallic record plates. No electrical or other power source is needed to make the records, so that the instrument may stand by for many years without attention. The case has, typically, about sixteen separate compartments with a recording unit installed in each. Each unit has a different natural (resonant) frequency, in the range between about 1 to 32 Hz. The record plates are all alike, except for keying or locating grooves, and all the recording units are made to have about the same sensitivity in terms of stylus deflection per unit acceleration. A problem addressed here is that in any simple linear mass-spring system, the static sag (deflection of the mass at 1 g) is inherently related to the natural frequency by an inverse square law.

Abstract: Apparatus is provided for testing the strength of a seal provided between an underlying substrate material and an overlying sheet material of a container. The package is inflated through an inflation needle inserted into the container. The pressure in the container is sensed through a sensing needle inserted therein. The apparatus may be used to test the tensile strength of the seal, and the location of any leaks therein.

Abstract: Apparatus for sensing and recording changes in the velocity of a vehicle involved in a crash comprises a sensing mass biased to an initial position in which it remains until it is acted upon by an acceleration pulse of such magnitude as to overcome the biasing force, whereupon the mass moves from its initial position a distance proportional to the magnitude and duration of such pulse. If the magnitude and duration of the pulse are less than preselected values, decay of the pulse enables the biasing force to return the mass to its initial position. If the magnitude and duration of the pulse are greater than such preselected values, however, retaining means act on the mass to retain the latter in its position of maximum movement from its initial position, thereby providing an indication of the velocity change. Preferably, indicia is associated with a sensing means to facilitate determination of the velocity change.

Abstract: The instant invention relates to a device for testing the end buckling strength of a can body wherein a uniquely disposed compressible ring- or doughnut-like member of appropriate elastic material is adapted to be compressed against the inside surface of a metal or container for the purpose of sealing the interior of the metal can from the atmosphere. The sealed interior of the can is then subjected to appropriate fluid or air pressure to determine the buckling characteristics of the can's closed end structure, after which the can body can be released from the testing device in an improved fashion.

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: A closed receptacle has a wall defining an internal space in which the sampling cell is fixed in a stable position, and an external wall into which opens, through an aperture, a connecting conduit connected to the internal space. The receptacle has a removable seal which seals the periphery of the aperture. The apparatus includes a removable means for testing the receptacle, which defines together with the external wall of the receptacle, a sealed zone surrounding the connecting conduit and which communicates with pressure measuring means. The removable testing means includes a key for loosening and tightening the removable seal to permit testing the receptacle for sample leakage without loss of the contents of the receptacle.

Abstract: In order to evacuate a receptacle using a pumping arrangement composed of a backing pump connected to the receptacle and a fine or high vacuum pump connected to the receptacle via a cold trap, the receptacle is initially evacuated only by operation of the backing pump, the time taken to achieve a predetermined initial pressure reduction in the receptacle only by the action of the backing pump is measured, then, on the basis of the magnitude of such pressure reduction and the measured time period, the subsequent time period which would be required, if the effect of condensable gases in the receptacle were ignored, to reach a predetermined second pressure, lower than the first pressure, in the operating range of the fine or high vacuum pump is calculated, and the receptacle is then evacuated by operation of the fine or high vacuum pump at the expiration of the subsequent time period.

Abstract: A system is disclosed for detecting the leakage of fluid from a container by measuring the decay of an initial pressure input. The system employs an axially displaceable piston having a first surface exposed to fluid pressure within the container, and a second surface opposed to the first surface, having a first portion exposed to a reference gas pressure, and a second portion not so exposed. A gas jet has an inlet connected to a pressure sensing source and a sensing gas pressure detector with an outlet proximate to the second portion of the second surface of the piston. Changes in the relative magnitude of the fluid pressure within the container with respect to the reference gas pressure will cause the piston to alternately block and unblock the outlet of the gas jet, producing a low pressure gas signal. This device is termed the "monitor".

Abstract: A method of high sensitivity for measuring leakage of liquid from a storage tank which comprises introducing a sensor into the liquid in the tank, the sensor being coupled to means for sensing displacement of mass, measuring the displacement over a known period of time and calculating the leakage rate. The sensor is designed to compensate for evaporative losses and temperature changes.