Abstract: The present invention provides methods and systems for forming deposition films on semiconductor wafers. In particular, the present invention measures the amount of liquid remaining in a bubbler ampule of a semiconductor processing system used for chemical vapor deposition (CVD) on a semiconductor wafer. More particularly, measurements are made when gas has stopped flowing through the ampule, and the liquid is in a static condition. The system of the present invention comprises a container containing a liquid, a gas inlet for introduction of gas into the liquid, a gas outlet, and a pressure transducer fluidly connected to the gas inlet and the gas outlet. The device measures the amount of liquid in a bubbler ampule through measurements of gas pressure differential between gas exiting a nozzle near the bottom of the liquid and gas located above the level of the liquid. The depth of liquid remaining in the ampule may be extrapolated from the measured pressure differential.

Abstract: The level measuring device (12) has a measuring tube (14) that is disposed in the fuel tank (10) and is filled by a partial flow of the fuel delivered to the injection system (44) of the engine (46) of the motor vehicle by a delivery unit (40) disposed in the fuel tank (10). On its one measurement input (26), a differential pressure sensor (24) is acted on by the hydrostatic pressure at the bottom end (30) of the measuring tube (14) and on its other measurement input (28), the sensor is acted on by the hydrostatic pressure at the bottom (16) of the fuel tank (10). When the delivery unit (40) is operating, a fuel column of a known height (lo) is produced in the measuring tube (14), so that the current level (h(t)) of the fuel tank (10) can be determined in an evaluation device (32) based on the output signal (u) of the differential pressure sensor (24).

Abstract: A hydrostatic pressure equalizer device is attached to the lower submerged end of a gas supply line. A hollow housing forms an internal cavity having a closed upper end and a lower end, and an end plate extends over at least part of the lower end to leave a gap for liquid flow into the cavity. The gas supply line extends through the end plate and upwardly into the cavity to terminate at a raised position which will be in an air pocket above the liquid level in the cavity. A pressure monitoring instrument connected to the line detects pressure in the air pocket, which in turn is equal to the hydrostatic pressure in the cavity and the surrounding liquid.

Abstract: Magnetic force from a momentarily excited coil (34) results in oscillatory flexure of a flexible diaphragm (30) loaded on one side by a liquid (10) whose level is to be measured. A strain gauge (46) detects the diaphragm flexure, and analysis circuitry (62) determines the liquid level as a function of the resultant oscillation frequency and the diaphragm's static flexure.

Abstract: The invention is directed to a method for detecting a fill level of a tank system utilizing a pressure source, a bridge divider arrangement and a pressure measuring device. The pressure source is adapted to generate a change of pressure in the tank system. The pressure divider arrangement has a reference measuring unit which can be charged with pressure by the pressure source. The reference measuring unit further includes at least one flow resistor of a predetermined size in at least one reference flow branch. For measuring the tightness, the pressure measuring device simultaneously detects the difference of the pressure in the tank system and of the pressure in the reference measuring unit. In the method, the time-dependent trace of the difference pressure during at least one of a pressure build-up operation and a pressure decay operation is continuously detected. A conclusion is then drawn as to the fill level from the time-dependent trace.

Abstract: An object of the present invention is to prevent erroneous operation of a liquid level sensor due to deposition of ammonium fluoride dissolved in buffered hydrofluoric acid used as a process solution.The present invention provides a liquid level sensor comprising a chemical solution bath for receiving a chemical solution including buffered hydrofluoric acid, a gas feed tube for introducing a gas for detecting the variation in the liquid level of said chemical solution into said chemical solution, and a gas pressure detector for detecting a change in the pressure of said gas and converting it into an electric signal to indicate a change in liquid level, characterized in that the diameter of a gas outlet provided at an end of said gas feed tube is smaller than the inner diameter of said gas feed tube.

Abstract: A transmitter housing for connecting a water level transmitter to a lye runoff bellows in a washing machine, the transmitter housing having an elongated and cylindrical shape and being connected at a basal end face thereof to a corresponding nozzle of a lye runoff bellows of a tub of the washing machine and being connected by the other basal end face thereof to the water level transmitter, includes a transmitter housing body having one of a jet molded and an injection molded generally hollow-cylindrical shape and includes devices for fastening the transmitter housing body to the nozzle of the lye runoff bellows, and devices for connecting the transmitter housing body to a body of the tub.

Abstract: A liquid level monitor using a pressure actuated sensor to replace the open bubble tube. Air flows down the supply tube as in the bubbler, but rather than being released into the water, the air enters a chamber that has one movable wall, such as a diaphragm, that is acted on from the inside by pressurized air and from the outside by the hydrostatic head of the water. When the water pressure exceeds the chamber air pressure, the movable wall is pressed against an air outlet and does not allow air in the chamber to escape through the air outlet. One embodiment uses a diaphragm disposed over the air outlet; however, the concept may be extended to several other movable members, such as a piston with low actuation force. When the air chamber pressure exceeds the water pressure, the movable member moves away from the air outlet, releasing air and causing the chamber pressure to drop down to the water pressure.

Abstract: An apparatus for the measurement of liquid quantity, comprising a frame (12) with a chamber space (13) inside it, an inlet duct (8) in the top part of the frame to pass a liquid into the chamber space (13), an outlet duct (11) in the bottom part of the frame to pass the liquid out of the chamber space (13) and elements (1, 2) placed in the chamber space (13) to form a weir container, said elements comprising a wall (2) and at least one orifice (1) formed in the wall, through which orifice (1) the liquid is passed out into the outlet duct (11), and means (3) for measuring the level of the liquid in the chamber space (13). The apparatus comprises means (10) for directing the liquid entering the chamber via the inlet duct (8) into at least two sub-flows (14, 15) and for directing these sub-flows from different directions to a point near the orifice (1) in the wall so that when the sub-flows (14, 15) meet again, they substantially damp the flow.

Abstract: The blood volume in a soft-shell venous reservoir is measured by immersing the reservoir in a fluid and measuring the displacement of that fluid, either by measuring a liquid level in an overflow tube or by measuring the temperature-compensated gas pressure if the displaced fluid is a gas in a sealed container. Equipment operable from outside the container to measure the reservoir or to expel air therefrom is also disclosed.

Abstract: A remote seal differential pressure transmitter, when installed with its remote seal separated by a vertical distance, has an accurate output signal which is compensated for all temperature effects, including compensation of the sensors' temperature characteristics and compensation of the remote seals' temperature characteristics. Compensation for the remote seals' temperature characteristics must include compensation for the expansion and contraction of the translation fluid used in the remote seals and compensation for changes in density of the translation fluid. The changes in density and the installed height of remote seals specifically create a height/temperature error which must be compensated for when the temperature changes.

Abstract: The apparatus measures the liquid volume of a liquid or liquids held in one or more containers. This apparatus has no moving parts and includes an open-ended dynamic pressure tube standing in each container with its open tube end at the lowest point of the container on the bottom surface of it and a pressure measurement converter closing the other tube end so as to form an air column between the pressure measurement converter and a liquid level in it. The apparatus also includes an electronic analyzing device (3,4) including an electronic circuit (3) connected electrically to the pressure measurement converter and producing an electronic signal characteristic of a liquid volume in the container and a digital meter for displaying a volume reading.

Abstract: For the apparatus and method to measure the water depth and level using a gas bubble type level meter, the measurement pipe for water column pressure is composed of plastic pipes of inside diameter of 2-4 mm; two measurement pipes for water column pressure are bounded that the elevation difference between the ends of two measurement pipes for water column pressure is .DELTA.

Abstract: A condensation vessel for the measurement of steam pressure includes a steam zone, a steam line which opens in the steam zone at an entrance, a condensate zone which is directly adjacent the steam zone and geodetically below the entrance, and a discharge device which is connected to the steam zone and which serves for a discharge of steam and noncondensable gases from the condensation vessel. A method for operating the condensation vessel includes condensing steam which contains an increased fraction of a noncondensable gas, in particular radiolysis gas, out of the steam zone. The gas is led out of the condensation vessel in dissolved form through the discharge device, with the result that the risk of faulty measurement is largely ruled out, since virtually no gas is dissolved in the condensate within the condensate zone. The condensation vessel can be installed in a simple way, even in the course of retrofitting, for measuring the filling level of a reactor pressure vessel.

Abstract: Apparatus and method for determining when the depth of molten (18) poured into a vessel (12) has reached a selected level. A conduit (22) connected to a source of pressurized gas and having an orifice (43) at its distal end (38) restricts the flow of gas out of the conduit which is positioned at a selected level in the vessel. A drop in pressure in the conduit (22) resulting from escape of compressed gas when the distal end (38) is melted by the rising molten metal is detected and signalled to a visible, audible indicator or directly to an electronic controller to discontinue pouring of metal (18) into the vessel (12).

Abstract: An improved liquid pressure measuring system comprising a container containing a liquid at a level to be sensed, a pressure sensing chamber located within said container and having an open bottom, a pressure sensing device connected to sense the pressure in said chamber, and means for generating gas within said chamber to balance the hydrostatic pressure of said liquid.

Abstract: An improved flowmeter sensor for measuring the level of liquid flowing in a conduit, pipe or open channel, characterized by an initially air-filled pressure transmitting passage which affords communication between a pressure port contained in the bottom of the sensor body, and a pressure transducer contained in the sensor body. The passage includes a vertical portion communicating at its lower end with the pressure port, and a horizontal portion connected with the transducer, whereby hydraulic pressure forces liquid into the passage to compress the air therein and thereby exert on the pressure transducer a pressure corresponding to the level of liquid in the conduit. The cross-sectional area and high surface energy of the material used to form the passage prevent liquid in the passage from migrating to the pressure transducer.

Abstract: A liquid level monitoring system, which monitors the level of liquid in a storage tank, includes a differential pressure sensor that uses a magnetic fluid, or ferrofluid, sensing element. The pressure sensor is U-shaped with a first one leg connected, via a first pressure chamber, to a bubbler tube that extends downwardly into the storage tank. The second leg of the U-shaped sensor connects to a second pressure chamber, which applies to the second leg a selected, fixed pressure. The pressure applied to the first leg of the sensor is proportional to the hydrostatic back pressure in the bubbler tube, which varies directly with the level of liquid in the storage tank. Wound around the legs of the pressure sensor are inductance coils. The inductances of these coils change as the ferrofluid sensing element moves within the sensor. Accordingly, the inductances change as the level of liquid in the storage tank varies.

Abstract: A differential pressure detection equipment typically represented by a water level measuring apparatus provided for a nuclear power plant includes a condenser having a steam flow-in port connected to a steam phase side pressure detector through a connection pipe, a reference water column side instrument pipe connected to a bottom portion of the condenser, a variable water column side instrument pipe connected to a liquid phase side pressure detector and a pressure difference detector connected to both the instrument pipes for detecting a pressure difference between a reference water head pressure of the reference water column side instrument pipe and a variable water head pressure of the variable water column side instrument pipe. The connection pipe has an upward inclination .theta. from the steam phase side pressure detector to the condenser so as to satisfy an equation of 0<tan .theta.<D/L, in which D is an inner diameter of the connection pipe and L is an axial length of the connection pipe.

Abstract: A liquid level sensing and monitoring system for a medical fluid infusion system has an IV spike with a pressure sensor which contacts fluid in an infusion container such as an IV bag or bottle. When an adequate amount of fluid is in the container, the resulting pressure on the sensor is at a relatively high level; however, when the fluid reservoir is nearly depleted, the pressure on the sensor falls to a low level, thereby activating the sensor and associated control circuitry which operates an alarm or warning indicator. In lieu of the pressure sensor, the device may use a resistive or capacitive sensor. When the liquid level falls below the electrical sensor, its state changes, and the alarm circuitry is activated.

Abstract: Pressure sensors positioned at strategic points on a floating vessel below the surface of the water provide depth information to a shore based control computer via wireless telemetry. The pressure sensors provide continuous information regarding the draft and inclination of the vessel as it is being loaded. The depth information produced by the pressure signals is telemetered to the control computer via transmitting units positioned on the floating vessel and a shore based receiver. The control computer compares the information from the pressure sensors to desired loading characteristics for the vessel and controls the loading process by sending control signals to a loader controller to adjust the point of loading. The point of loading is maintained so as to keep the vessel within desired trim and draft limits. Loading ceases when a desired amount of material has been delivered into the barge or when the barge is at the desired draft in a level state.

Abstract: A system for determining the level of coolant in a depressurized nuclear reactor comprises a first set of pressure transducers located in the coolant piping and a second set of pressure tranducers located at the top or near the top of the pressurizer. Electrical signals from these independent transducers are fed by cable to a controller with a microprocessor in the reactor control room where the coolant level is calculated and displayed. Compensations for signal error, coolant temperature and coolant chemistry are provided.

Abstract: A method for filling a tank with a predetermined weight of liquid is described. This method is useful wherever floats or other volumetric dependent modes of measurement do not yield the desired information. Firstly, calculate the pressure differential required to overcome internal tank pressure and force a non-turbulent stream of bubbles from a bottom of a tank when the tank is filled with a known predetermined weight of liquid, thereby setting a standard for comparison purposes. Secondly, monitor the pressure differential required to overcome internal tank pressure and force a non-turbulent stream of bubbles from a bottom of the tank as a flow of liquid is entering the tank.

Abstract: A liquid level instrumentation measurement system for measuring the level of liquid under high pressure in a pressure vessel containing liquid and vapor with non-condensable gases. The system includes a reference leg outside the pressure vessel, a condensing chamber at the upper end of the reference leg defining a vapor space in which vapor condenses to keep the reference leg filled with liquid, a variable leg connected near the bottom of the pressure vessel, and a differential pressure detector connected to both the variable leg and the reference leg for generating a signal proportional to the level of liquid in the pressure vessel. A vent outlet is disposed in the condensing chamber to which a vent leg is connected. The vent leg may be disposed between the vent outlet in the condensing chamber and the variable leg or between the vent outlet and the head vent line which connects the pressure vessel to a main vapor line.

Abstract: Precise information about the position of a liquid-liquid interface (28, 32) is often important for the control and automation of molten metal refining processes. For example, in an electrolytic process for removing magnesium from molten aluminum, knowledge of the vertical position of an interface (32) between the electrolyte and the magnesium and an interface (28) between the electrolyte and the aluminum facilitates the automatic removal of the purified metals. Differences in surface tension in the fluid layers of a molten electrolytic salt (30) and a molten metal (29) produce different pressures as bubbles (57) evolved from vertically displaced tips (52) of tubes (34, 36) press against the liquid layers on either side of their interfaces (28, 32).

Abstract: A method of measuring and indicating a level of natural gas fuel in a storage tank of a motor vehicle, comprising the steps of determining a temperature of the natural gas, determining a pressure of the natural gas, retrieving from a look-up table, responsive to the determined temperature and pressure, a signal representative of a percentage that the tank is full of the natural gas, determining a gauge command responsive to the signal, and driving the gauge according to the determined command.

Abstract: A device for detecting the fluid level in the tank of a motor vehicle has a tank leaktightness testing device, a gas evolution testing device for testing whether the fuel in the tank vaporizes, a pumping-out/sequence control deice for subjecting the tank to a change procedure, a gradient detection device for detecting the value of a pressure change gradient parameter from at least one pressure change and one time period associated therewith, and a fluid level output device which receives the signals from the tank leaktightness testing device, the gas evolution testing device and the gradient detection device in order to output the instantaneous value of the fluid level with the aid of a known interrelation between pressure change gradient parameter and fluid level whenever the tank is sufficiently leaktight and the vaporization of the fuel is sufficiently low.

Abstract: A system for continuously monitoring fills of liquid such as fuel oil in a tank, and the condition of the liquid. A dual in-line air bell structure senses fluid pressure at upper and lower locations inside the tank, the locations being spaced a known distance apart from one another in a normal direction relative to the tank. Processing circuitry responsive to the fluid pressures obtained via the air bell structure, determines quantities of liquid contained in the tank at certain times and produces corresponding outputs such as gallons of liquid delivered to the tank at each of a number of delivery times, and total gallons of liquid in the tank as the liquid is consumed. The air bell structure is formed with upper and lower air bell sections joined end-to-end along a common axis. Each of the air bell sections includes at least one aperture in its wall to define a cross-section through the air bell section.

Abstract: An apparatus for determining the pressure distribution along a limited distance comprises a plurality of pressure sensors arranged at predetermined distances to each other and connected to an evaluation circuit, the pressure sensors being arranged, in particular embedded, in/at a preferably round rope-type body of elastomeric material, the body being surrounded by a non-elastic, however in radial direction deformable cover in fixed connection thereto. The apparatus may be advantageously used as a filling level indicator in a bin or for various other purposes.

Abstract: A system and method for providing for a remote readout of liquid levels in an oil tank, which system includes an oil tank having an air vent and containing liquid amounts whose levels are to be determined; a single bubble tube inserted in the oil tank, with one end adjacent the bottom surface of the oil tank; an integral source of compressed air for supply to the single bubble tube; a pressure sensor and a timer actuated on demand or periodically at a fixed time, to actuate the integral air compressor for a short defined time period, and immediately thereafter to actuate the pressure sensor, to sense the amount or level of the oil in the oil tank; manual or telephone actuation of the timer, when determination of the amount or level of the oil in the oil tank is desired; and a computer-memory and display means at a remote location, to receive and display to the user the information on the amount or level of oil in the oil tank.

Abstract: The water level of an above-ground swimming pool is maintained at a predetermined level by a small tank attached to the edge of the pool. The conduit is comprised of a Y-connection fitting having a stem and two arm portions. An eye is attached to the fitting by an eye housing and eye cap. A nut is provided for securing the fitting to a pool sidewall. The fitting contains radial apertures and longitudinal passageways which permit water to flow into, and out of, the pool simultaneously.

Abstract: An automated liquid holding tank and method for automatically filling a liquid holding tank. The tank comprises a holding tank with dispensers for filling the tank with liquids and a pressure sensor attached to the tank for measuring the liquid level within the tank. The pressure sensor also provides a tank liquid level indicator output signal which is sent to a controller that compares the output signal with a pre-set value. When the output signal matches the pre-set value the controller closes the dispensers. The pressure sensor includes a gas bubble within a connecting tube to communicate the tank liquid pressure to the pressure sensor.

Abstract: A system (10) and methods of use for determining the level of a body of liquid (16), e.g., a chemical, in a storage tank, irrespective of the specific gravity of that liquid. The system (10) comprises a pressure transducer (22) and an elongated tubular, flexible sheath (24). An operating liquid (26) of lower specific gravity than the body of liquid (16) is disposed within the sheath (24). The transducer (22) is also disposed within the sheath adjacent the bottom end. The sheath (24) is immersed in the body of liquid (16) so that its top end (28) is above the liquid's surface. The pressure applied to the sheath (24) by the liquid (16) causes the sheath to collapse to a minimal internal cross sectional area, whereupon the operating liquid migrates up the sheath to form a very thin column (44). The operating liquid forming a pool (46) is located at the top of the very thin column (44). Thus, the sheath expands outward adjacent the surface (16A) of the body of liquid to retain that pool.

Abstract: There is provided a closed loop system for measuring an amount of liquid under pressure in a container. The system comprises a container holding a liquid under pressure, a novel differential valve with check valves which are connected to the container and to a differential gauge, and a means for activating the valve.

Abstract: There is provided a closed loop system for measuring an amount of liquid under pressure in a container. The system comprises a container holding a liquid under pressure, a novel differential valve with check valves which are connected to the container and to a differential gauge, and a means for activating the valve.

Abstract: There is provided a closed loop system for measuring an amount of liquid under pressure in a container. The system comprises a container holder a liquid under pressure, a novel differential valve with check valves which are connected to the container and to a differential gauge, and a means for activating the valve.

Abstract: A system for measuring level of liquid material in a containment vessel that includes a hollow conduit composed of a first conduit section having an upper end coupled to a pressure sensor and a lower end disposed within the vessel. A second conduit section is coupled to the lower end of the first conduit section and extends downwardly therefrom at least to a minimum material measurement level within the vessel. The second conduit section has a vertical height coordinated with the maximum desired material measurement level within the vessel such that pressure of air captured within the first conduit section at such maximum material level prevents entry of the liquid material into the first conduit section. The cross sectional area of air flow within the second conduit section is at least ten times, and preferably at least sixteen times, greater than the cross sectional area to air flow within the first conduit section.

Abstract: A fiber-optic liquid level sensor measures the height of a column of liquid through the hydrostatic pressure it produces. The sensor employs a fiber-optic displacement sensor to detect the pressure-induced displacement of the center of a corrugated diaphragm.

Abstract: A self-contained, submerged aparatus for monitoring the height of a liquid in a wetwell includes a tube defining an upright conduit, a first chamber at the bottom of the conduit and communicating with it, a second chamber adjacent the first chamber and separated from it by a first impervious non-rigid membrane, the second chamber being defined in part by a second impervious non-rigid membrane in contact with the liquid in the wetwell. The second chamber contains a first liquid to which the membranes are inert, and the first chamber contains a second liquid to which the first membrane is inert. Pressure from the liquid in the wetwell exerted against the first membrane is transmitted to the second membrane and causes the second liquid to rise in the tube. The top of the tube is vented to the atmosphere, and a plurality of electrical terminals disposed at spaced locations lengthwise of the tube are provided for producing a signal which is a function of the height of the second liquid in the conduit.

Abstract: Each unit of an array of submerged oceanographic devices is provided with a depth gauge of the air bubbler type. A typical depth gauge consists of a tube or air line that has one end fluidly coupled to a manifold; the other end of the air line is open. The open end of the air line is secured adjacent a corresponding submerged device. A small flow of air is established from the manifold, through the air line, to bubble out the open end into the water. A pressure transducer is fluidly coupled to the air line and senses the backpressure due to the hydrostatic water head existing above the submerged device. Means are provided for inhibiting pneumatic cross feed in the manifold between the respective air lines.

Abstract: Method and system for measuring vertical density profile of fluid by pressurizing an array of pipes, determining level and pressure signals on each pipe and deriving profile therefrom.

Abstract: An apparatus for measuring a level of a cryogenic fluid in a cryostat includes a semiconductor pressure sensor mounted at the end of an elongated vertically disposed tube. The semiconductor pressure sensor is located at the bottom of the tube and is sealed in the bottom of the tube by a polymeric insulating material. The upper end of the tube is provided with a vent hole which communicates vapor pressure within the cryostat to the interior of the tube. The pressure sensor outputs an electrical signal in accordance with the differential pressure exerted on a semiconductor element of the pressure sensor from opposite sides by the vapor pressure within the tube and the fluid pressure outside the tube.

Abstract: A device for multimeasurement of vertical position variation of one or a number of predetermined points of an industrial or scientific construction of installation comprises means for measuring pressure which appears at the locations of these points and the variation of which is directly related to a variation in level of said points.

Abstract: A method and apparatus for monitoring liquid levels using pressure responsive instruments is described, in which an arrangement for compensating for the effects of errors including gas weights errors is provided. The required compensation factor for a particular installation is first calculated theoretically, and then used in order to raise the output signal of the instrument electronically by the calculated factor. In one arrangement, the output signal is amplified by the desired factor. Alternatively, the excitation voltage of the instrument itself, or of a potentiometer used to interface the instrument to electronic data acquisition devices, is varied in order to raise its output voltage by the desired compensation factor.

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 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: A fuel delivery system for automotive engine and like applications comprises a canister for positioning within a fuel tank so as to be surrounded by fuel in the tank. An electric-motor fuel pump has an inlet and an outlet for feeding fuel under pressure from the tank to the engine. Excess fuel is returned from the engine to the canister. A fuel level sensor includes a pressure sensor positioned at a lower portion of the canister and responsive to head pressure within the canister and within the surrounding tank for providing an electrical signal as a function of a difference between such pressures. An indicator is responsive to such electrical signal for displaying tank fuel level to an operator.

Abstract: A gauge is disclosed which is particularly suitable for use on stand-alone liquid storage tanks typically found outdoors or on worksites. Fluid from the lower portion of the tank is allowed to flow into a chamber bounded on one side by a resilient deformable diaphragm. The pressure exerted by the fluid deforms the diaphragm displacing it outward, which displacement is mechanically transmitted to cause pivotal displacement of an indicator needle. The amount of displacement of the needle depends upon the magnitude of the fluid pressure, which itself is proportional to the depth of the liquid in the tank, thus providing a reading of that depth.

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.