Abstract: A measurement system includes a vessel for containing a fluid and at least one solid material and a probe assembly for disposing partially into the fluid within the vessel. The probe assembly includes a hollow tube having an open lower longitudinal end and at least one pressure sensor within the hollow tube, the at least one pressure sensor configured to measure pressures of the fluid within the hollow tube at at least two different elevations. A method of measuring a mass of suspended solids within a fluid, the method includes receiving pressure measurements representing two different elevations of the fluid within a hollow tube and substantially free of the suspended solids and based at least partially on the received pressure measurements, determining a mass of the suspended solids.

Abstract: The invention relates to a pressurized gas container, in particular a gas cylinder, having an internal volume for gas storage, a fluid-distributing valve, a pressure sensor and microprocessor-based control means. The microprocessor-based control means are configured to detect filling of the gas container with gas, by comparing said at least one pressure value measured by the pressure sensor with at least one predefined and stored reference pressure threshold value; then to initiate a timer on the basis of a detection of filling of the gas container with gas; and to trigger a warning when the timer exceeds a given period calculated from the initiation of the timer.

Abstract: A hydraulic leak detection system includes a leak detection switch responsive to a level of hydraulic fluid in a tank used by a hydraulic mowing circuit and a lift and lower circuit of a grass mowing machine. The system includes a controller that activates a warning indicator if the leak detection switch indicates the level of hydraulic fluid in the tank is low, but allows the hydraulic mowing circuit and the lift and lower circuit to continue operating until the lift and lower circuit reaches a fully raised position. A solenoid valve may control the level of hydraulic fluid in the tank based on temperature of the hydraulic fluid.

Abstract: A bubbler device and method of its operation are disclosed. The bubbler device includes a bubbler tube that provides bubbles to a molten material in a furnace; a protective layer disposed on the bubbler tube; and a wire that is electrically coupled to the protective layer. The wire extends through the bore, and the protective layer and the wire partially form an electrical circuit for measuring integrity of the bubbler device based on at least one of conductivity or resistance in the electrical circuit. Sometimes, an inner protective material may be disposed on an inside surface of the tube and coupled to the protective layer, and the wire can be coupled to the inner protective material or multiple wires may be used. The use of dissimilar materials in these components may be used to form a thermocouple junction to measure the temperature of the molten material in a furnace.

Abstract: A pressure sensing device for sensing pressure. The pressure sensing device includes a sealed chamber, a second flexible diaphragm, and a protector member. The sealed chamber includes an upper portion comprising a first flexible diaphragm and a lower portion. The protector member includes a bottom surface with a fist concave shape, a top surface with a second concave shape, and a longitudinal hole between a lower cavity and an upper cavity. The lower cavity is between the first flexible diaphragm and a bottom surface of the protector member. The upper cavity is between the second flexible diaphragm and an upper surface of the protector member.

Abstract: A cap with refill capability and the ability to track various aspects of the tote, cap, and equipment has been developed for use on chemical totes. It provides the ability to refill the tote without removing the cap and remove water from the fluid and air in the hose.

Abstract: An assembly includes at least one container, an injection medium supply, at least one flow line extending from the injection medium supply to an interior portion of the at least one container; and a pressure transducer coupled to each of the at least one flow line.

Abstract: An expansion tank for the coolant of a fluid-cooled machine, in particular a machine-operated water-borne vehicle or a truck includes at least one inlet connection arranged in the lower region of the expansion tank, and an outlet connection for connection of the expansion tank to a cooling circuit of an internal combustion engine. A filler nozzle is arranged in the upper region of the expansion tank and has a lower edge spaced from an expansion tank cover to limit the fill level. At least one valve seals the filler nozzle for filling the expansion tank and protects the cooling system from over-pressure. Furthermore, an air volume in the expansion tank, which remains on maximum filling of the expansion tank with coolant, can be adjusted.

Abstract: Subsea equipment-protection apparatus including a fluid monitoring apparatus for detecting a first fluid, a second fluid and a third fluid. The fluid monitoring apparatus including a first float having a density less than that of the first fluid but greater than that of the second fluid; a second float having a density less than that of the second fluid but greater than that of the third fluid; and a sensor configured to detect the first and second floats so that the position of the floats can be determined. The first float floating when a fluid with density greater than the first float is present and sinking when a fluid with density less than the first float is present. The second float floating when a fluid with a density greater than the second float is present and sinking when a fluid with a density less than the second float is present.

Abstract: An air flow rate adjusting apparatus adjusts an output of an air flow meter based on a dimension of a gap between a back surface of a sensor chip and a bottom surface of a recess of a support plate.

Abstract: A liquid level sensor comprising an inner capacitor tube, an outer capacitor tube and a probe foot suitable for placing the liquid level sensor on a bottom surface of a liquid tank, wherein a capacitor region arranged to hold a liquid is defined between the outer capacitor tube and the inner capacitor tube, and wherein an insulating minimum distance is left between the inner capacitor tube base and the probe foot, the insulating minimum distance being sufficient to prevent a droplet of water on the probe foot from making contact with the inner capacitor tube.

Abstract: Acoustic volume indicators for determining liquid or gas volume within a container comprise a contactor to vibrate a container wall, a detector to receive vibration data from the container wall, a processor to convert vibration data to frequency information and compare the frequency information to characteristic container frequency vs. volume data to obtain the measured volume, and an indicator for displaying the measured volume. The processor may comprise a microprocessor disposed within a housing having lights that each represent a particular volume. The microprocessor is calibrated to provide an output signal to a light that indicates the container volume. The processor may comprise a computer and computer program that converts the data to frequency information, analyzes the frequency information to identify a peak frequency, compares the peak frequency to the characteristic frequency vs. volume data to determine the measured volume, and displays the measured volume on a video monitor.

Abstract: A device arranged for measuring a level of a liquid in a container. The device has a sensor, arranged to sense a pressure of a liquid in a tube, a pump arranged to pump the liquid from the container through the tube, and a valve located along the tube between the sensor and the pump and arranged to impede back flow of the liquid into the container when the pump stops pumping the liquid. The device is arranged to measure the level of the liquid into the container on the basis of the hydrostatic pressure measured by the sensor after each stop of the pump. Also disclosed is a method for measuring a level of a liquid in a container by a pressure sensor.

Abstract: A multi-tank indirect liquid level measurement device and method for wastewater tanks in a recreational vehicle may be implemented using a sealable reservoir that holds pressurized air, a manual piston pump that supplies and/or pressurizes the air in the reservoir, a rotary valve that incorporates a selection disk with an axial passage that is rotationally coupled to a connection disk that has a plurality of pipes, each of which connect on their other end to the wastewater tanks to be gaged. A bourdon tube pressure gage displays the pressure difference between the sealable reservoir and atmospheric pressure, which is an indirect reading of the height of the wastewater in the tank being gaged.

Abstract: In one embodiment, a flow-estimation processor receives one or more flow-depth measurements with each flow-depth measurement having been taken at a respective time. The processor calculates a respective estimated flow rate for each of the times based on the corresponding flow-depth measurement and one or more flow-estimation parameters each set to a respective initial value. The processor outputs the estimated flow rates for presentation via a user interface, and receives via the user interface one or more updated values corresponding respectively to a flow-estimation parameter. The processor calculates an updated estimated flow rate for each of the one or more times, such that each respective updated estimated flow rate is calculated based on the received updated values. The processor then outputs the updated estimated flow rates for presentation via the user interface.

Abstract: An outer tank and an inner tank having liquid at different temperatures, and a load are connected to each other via outer and inner tank liquid circulating channels and a valve unit. A first opening-and-closing valve is connected to a first bypass flow-channel connecting an outer tank feed channel and an inner tank feedback channel, a second opening-and-closing valve is connected to a second bypass flow channel connecting an inner tank feed channel and an outer tank feedback channel to detect the liquid level of the liquid in the outer tank and the liquid level of the liquid in the inner tank by a liquid level sensor. The liquid levels are adjusted by selectively opening the first opening-and-closing valve and the second opening-and-closing valve when the liquid levels in both tanks become uneven in the process of cyclically feeding the liquid from the tanks to the load.

Abstract: A system, for use in determining a volume in a reservoir, includes a bulkhead, a plunger assembly, and a base. The plunger assembly is connected to the bulkhead. The plunger assembly includes a first plunger and a second plunger. The first plunger has a corresponding first biasing member. The second plunger has a corresponding second biasing member. The base of the reservoir is connected to the first plunger. Movement of the base causes compression or expansion of the first biasing member, which causes compression or expansion of the second biasing member. The bulkhead, the first plunger, and the base define a first portion of the reservoir. Positions of the first plunger and the base, relative to the bulkhead, are based on the volume in the reservoir.

Abstract: A multi-tank indirect liquid level measurement device and method are disclosed. The device and method may be implemented using a sealable reservoir that holds an indicating liquid and pressurized air, a pump that supplies and/or pressurizes the air in the reservoir, a plurality of pipes each of which connect on one end to the tanks to be gaged and on their other ends to a valve for selectively and exclusively connecting to the pressurized air, and a manometer tube that displays the pressure difference between the sealable reservoir and atmospheric pressure as a height reading of the indicating liquid.

Abstract: The present invention provides a method, device and apparatus for determining a quantity of fuel within a fuel tank having a drain valve penetrating a lower boundary of the fuel tank. The method includes inserting a pressure measurement probe having a pressure sensor into the drain valve to permit contact between the pressure sensor and fuel within the tank, and measuring a pressure of the fuel with the pressure sensor. The measured pressure is used to determine the quantity of fuel within the tank, e.g. by consulting look-up tables comprising data indicating the relationship between measured pressure and fuel quantity, or by using one or more conversion equations.

Abstract: A liquid level determination system comprises pressure determination components that include an interference dampener to mitigate interference originating from a bubbler air compressor. The system may include a pressure pipe with a pressure sensing pipe end located adjacent to the pressure determination components and a bubbler pipe end locatable at least partially in a wet well. The wet well may include a pump that has a volute. The pressure pipe may further comprise layered pipe sections, and the position of the bubbler pipe end may be calculated so that it is not lower than a level substantially equivalent to a center line through the volute. The bubbler air compressor may provide air pressure to the pressure pipe.

Abstract: Capillary depth gauge (1) including at least one capillary tube (2) of triangular section arranged against a background (3) opposite an observation surface (5) and visible by transparency from the observation surface when the tubular section is substantially filled with water, at least one reflection surface (4), visible by reflection from said observation surface when the tubular section is substantially filled with air, said tube forming an isosceles triangle whose equal angles (?) have an angular value of between 48 and 60 degrees.

Abstract: A method for determining an amount of liquid removed from a tank per unit time includes discontinuously feeding the liquid to exhaust gas of an internal combustion engine by at least feeding the liquid through an injection line into the exhaust gas, measuring pressures simultaneously at least at two points in the injection line and determining an amount of liquid fed in per unit time from the measured pressures. The amount of liquid removed between a first point in time and a second point in time is further derived by integrating the amounts of liquid removed per unit time over a period of time from the first point in time to the second point in time. The method allows the precise consumption of the liquid to be calculated and the remaining amount of liquid in the tank to be additionally determined. On-board diagnosis is further possible with the method.

Abstract: A liquid level determination system to determine the level of a liquid in a wet we is disclosed. The system may include pressure determination components and a pressure pipe with a pressure sensing pipe end located adjacent to the pressure determination components and a bubbler pipe end locatable at least partially in the wet well. A transducer is used to determine a pressure level within the pressure pipe maintained by a bubbler air compressor. A level detection processor may analyze the pressure level to determine a liquid level in the wet well. An interference dampener is included to mitigate interference originating from the bubbler air compressor. The interference dampener may be provided by transducer plug to restrict air flow. Alternatively, the interference dampener may be provided by a computer operated program to monitor and mitigate the interference.

Abstract: Capillary depth gauge (1) including at least one capillary tube (2) of triangular section arranged against a background (3) opposite an observation surface (5) and visible by transparency from the observation surface when the tubular section is substantially filled with water, at least one reflection surface (4), visible by reflection from said observation surface when the tubular section is substantially filled with air, said tube forming an isosceles triangle whose equal angles (?) have an angular value of between 48 and 60 degrees.

Abstract: A biological specimen collection and transfer system, comprises a biological sample container configured for storing a biological fluid sample, and a fluid level regulator configured to determine a fluid level in the biological sample container and to dispense a fluid into the container if the determined fluid level is less than a desired fluid level. A method of regulating a fluid level of a biological fluid sample in a container during a process of transferring biological matter in the fluid sample to a specimen slide, the method comprises monitoring a pressure of an interior chamber of a specimen filter, the chamber coupled to a vacuum source and having one end submerged in the fluid sample, determining a fluid level of the fluid sample in the container based on a detected change in pressure of the specimen filter chamber, and adding a liquid to the container if the determined fluid level is less than a desired fluid level.

Abstract: Water measurement auto-networks and methods of operation are disclosed herein. An exemplary method may include determining a water level at a first water measurement station in an auto-network. The method may also include reducing power to at least a transmitter at the first water measurement station to conserve battery power during an inactive state. The method may further include increasing power to the transmitter only at predetermined times to communicate the water measurement data to a second water measurement station in the auto-network.

Abstract: The invention may be used for detecting fluid leaks in a fluid containment element having a primary element enclosed in a secondary element. A fluid container may have a reservoir with an upstanding test cylinder with a selected fluid volume. A device may be disposed in the test cylinder to determine the level of a test fluid. There may be a closure for a top opening and the closure may have a hole. A nonexpandable conduit may connected at a first end to the hole and at a second end to a pressurized gas supply. The fluid container may have an outlet port therein and a first end of an outlet nonexpandable conduit may be connected to the outlet port. A block valve may be disposed in the outlet nonexpandable conduit. The fluid container may be pressurized by the introduction of a gas from the pressurized gas supply.

Abstract: In a water-bearing household appliance with a liquid container filled through a valve in a liquid feed line, and in which a liquid filling level is detected for monitoring at least one safety level of a safety device, the safety device includes an optical light guidance system for reflecting a light beam by which the filling level is detected with the aid of a change in the reflection response on at least one reflecting site and is used to monitor the safety level. As an optical light guidance system, the safety device offers the advantage of dispensing with moving mechanical components—for example, a float, a level switch, an operating lever, an operating rod, etc.—to reduce the risk of mechanical defects that are associated with a substantial outlay on repair time and costs to a minimum or to completely eliminate the risk.

Abstract: Method for controlling the level of a liquid (2) contained in at least one vessel (3), which comprises the following operative steps: inserting a measure tube (1) in the liquid (2); arranging an auxiliary duct (6; 21) inside or outside the vessel (3); measuring the pressure in said measure tube (1); measuring the pressure in said auxiliary duct (6; 21); determining the difference between the pressures in the measure tube (1) and in the auxiliary duct (6; 21); determining the value of the density or the specific weight of the liquid (2) in the vessel (3); dividing said pressure difference by said value of the density or specific weight of the liquid (2). The present invention also relates to an apparatus for carrying out said method.

Abstract: A system for monitoring the conditions within a storage tank includes a sensor communicating data indicative of conditions within the storage tank to a base controller. The data is decoded and arranged into a graphical display of the conditions of the storage tank. The graphical display includes a representation of storage tank conditions including the configuration of the storage tank, current fluid levels and temperature within the storage tank. The graphical display also includes a historical database of conditions within the storage tank that may be displayed graphically to track usage. The base controller is connected to a communications network such that data indicative of conditions with the storage tank can be communicated to remote users through a wireless communication network by way of alphanumeric messages.

Abstract: The invention relates to a method for determining the current filling level of a liquid, preferably a calibrating, quality control, or cleaning fluid, or waste water, in a container, for example of an analyzer, where an immersion pipe is dipped into the liquid in the container to be filled or drained. The immersion pipe is connected to a pumping device via a tube system. The pressure p in the tube system is measured and increased, starting from the ambient pressure p0, until a first discontinuous pressure change occurs at pressure p1 due to the liquid column in the immersion pipe being forced out of the pipe, and/or the pressure p in the tube system is decreased until the liquid column in the immersion pipe reaches a change in cross-section of the immersion pipe, which change is situated above the maximum filling level of the liquid, such that a second discontinuous pressure change occurs at pressure p2 due to the liquid column reaching the change in cross-section.

Abstract: A liquid-level measuring device measures the liquid level in a tank. This invention measures liquid level by measuring the pressure at the bottom of the tank. A pressure sensor is placed in the top sealed end of a pipe extending from above the top of the tank down to and open into the bottom of the tank. When the tank is empty the pressure is zero (relative to atmospheric pressure). As the liquid level of the tank rises from empty to full, the pressure rises according to the weight of the liquid. An electronic pressure sensor is used to measure the pressure. The output of the pressure sensor is amplified and sent to an operator display device.

Abstract: A self-regulating bubble tube assembly is used for determining the hydrostatic pressure exerted by fluids, such as drilling mud. The bubble tube assembly can be used to determine fluid level based upon said hydrostatic pressure and when bubble tubes are used in pairs can be used to determine a pressure differential that will indicate the density of the fluid. The bubble tube assembly comprises a flow of air directed through a diaphragm type pressure regulator. The pressure regulator output is connected to the bubble tube, which is partially submerged in the fluid, through a precision, in-line, flow limiting orifice. A feedback line from the bubble tube runs to one side of the diaphragm of the pressure regulator where the back pressure from the tube will regulate the output pressure from the regulator to maintain a pre-selected constant rate of air flow through the bubble tube.

Abstract: Method for controlling the level of a liquid (2) contained in at least one vessel (3), which comprises the following operative steps: inserting a measure tube (1) in the liquid (2); arranging an auxiliary duct (6; 21) inside or outside the vessel (3); measuring the pressure in said measure tube (1); measuring the pressure in said auxiliary duct (6; 21); determining the difference between the pressures in the measure tube (1) and in the auxiliary duct (6; 21); determining the value of the density or the specific weight of the liquid (2) in the vessel (3); dividing said pressure difference by said value of the density or specific weight of the liquid (2). The present invention also relates to an apparatus for carrying out said method.

Abstract: The present invention is a liquid depth sensing system utilizing the bubble tube or purge operating principle. In this system, a pneumatic tube extends downwardly into the liquid, and air (or other gas) passes through the tube to bubble from the lower end thereof. The air or gas pressure within the tube is equal to the head pressure of the liquid, thus allowing the liquid depth to be determined by measuring the air or gas pressure. The present system may be applied to either open or closed liquid containers (e. g., fuel quantity indication), and may be adapted for use in the bottling industry.

Abstract: A well water level sensing apparatus using a pressurized air column in contact with the water at its distal end to derive a correlated value dependent upon the length of the air column which is converted for retrieving stored water levels from memory and displaying the retrieved water levels on a visual display. The water level sensing apparatus may be manually initiated or programmatically controlled for continual monitoring.

Abstract: An ALC circuit is turned on (S1), a nozzle is shifted to a sampling position (S2), and after the ALC circuit has been turned off (S3), the nozzle is allowed to start discharging air from its tip (S4). While the nozzle is being lowered, the inner pressure of the nozzle is monitored (S5, S6), and upon detection of an increase in the pressure, the discharging process of air and the nozzle lowering process are stopped (S7), while the monitoring of the magnitude of the pressure is continued (S8). When the magnitude of the pressure is being maintained within a permissible range of the change for a predetermined time, it is judged that the tip of the nozzle has come into contact with the true liquid level, and after a suction operation of a sample (S9), the nozzle is raised (S10).

Abstract: A continuous liquid level measurement system is disclosed which is based upon a differential pressure measurement. The pressure of the liquid level to be measured is calibrated with a second pressure measurement of the pressure above the liquid in order to get a more accurate pressure measurement which is related in a predetermined manner to the level of the liquid. For instances in which the liquid to be measured is in a harsh environment, the invention provides for a means for mounting the sensitive pressure measurement devices remotely from the liquid.

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 process for generating at least one warning signal relating to the level in a tank (3) for storing a product (4) comprises the following steps:the storage level of the product in the tank, together with the values of the product quantity consumed during predefined time intervals are determined,these values are placed in memory together with the associated measurement instants,at other successive instantsthe values placed in memory of the product quantity consumed are used to calculate a value of the estimated quantity of product which will be consumed in the future,this estimated value is subtracted from the last measurement value so as to obtain an estimated value of the storage level at a future instant,this estimated value of the storage level is compared with a preset threshold, anda warning signal is generated if the estimated value is less than the preset threshold.

Abstract: The invention covers a procedure for measuring hydrostatic pressure, especially that of ground water, with the particularity that air is bubbled into the ground water, the pressure in the measuring pipe is fed to an absolute pressure cell and atmospheric pressure is then applied to the same measurement cell.

Abstract: A fail-safe fluid transfer control apparatus has full redundancy in the response to various inputs such as overfill probe signals, ground detection signals, and the like. Independent microprocessor controllers independently evaluate the inputs and each output control signals to close a respective relay when the inputs indicate that fluid transfer may commence. The relays are arranged in series such that both must be closed for a fluid transfer to commence. The control signals from each controller include a static signal and an alternating signal, both of which must be properly output to close its respective relay. Each controller monitors the state of each relay, and discontinues its control signals if either relay appears to be malfunctioning. Each controller runs an different, independently written firmware program to process the detected inputs to prevent a common firmware error.

Abstract: An installation and method for determining the level and density of a liquid in a tank. A reference probe leads into the tank, above the liquid. A single bubble probe is connected by a valve to the reference probe. The bubble probe extends into the tank and has a widened section disposed in the liquid. Compressed air is injected into the reference probe and the bubble probe. In an initial state, the valve is opened and there is no pressure difference between the reference probe and the bubble probe. The valve is then closed and the pressure difference between the reference probe and the bubble probe is measured. The level and density of the liquid is determined from measured values of the pressure difference.

Abstract: A method and apparatus for continuously monitoring fluid level in an oil well, by measuring changes in the weight of the oil well tubing which result from changes in the buoyancy of the tubing caused by the rise and fall of fluid level within the oil well. In the apparatus of the invention, a transducer is either affixed to the downhole tubing of the oil well, or alternatively, is affixed to the drive head support structure of a well having a progressive cavity well pump. The transducer continuously senses changes in the weight of the tubing as the buoyancy of the tubing changes in proportion to the rise and fall of fluid level within the well. The transducer is preferably connected to a control unit which, in turn, is connected to the pump motor and which functions to automatically control the pump motor as a function of fluid level within the well.

Abstract: A process for determining the quantity of a liquid situated in a largely closed system of a motor vehicle is provided. The filling level of the liquid in the system fluctuates as a function of the driving condition. In the case of a known process of this type for determining the engine oil quantity, the oil quantity determination takes place by filling level measurements while the vehicle is standing and the engine is switched off. The present process determines driving-condition-indicating quantities in the driving operation, determines therefrom the momentary driving condition, and, at least during selected driving conditions in the driving operation, continuously sense the filling level, as well as determines therefrom the momentary filling quantity via a given dependence of the liquid quantity on the driving condition and on the filling level. This permits, for example, a monitoring of the engine oil quantity in the continuous driving operation.

Abstract: A fail-safe fluid transfer control apparatus has full redundancy in the response to various inputs such as overfill probe signals, ground detection signals, and the like. Independent microprocessor controllers independently evaluate the inputs and each output control signals to close a respective relay when the inputs indicate that fluid transfer may commence. The relays are arranged in series such that both must be closed for a fluid transfer to commence. The control signals from each controller include a static signal and an alternating signal, both of which must be properly output to close its respective relay. Each controller monitors the state of each relay, and discontinues its control signals if either relay appears to be malfunctioning. Each controller runs an different, independently written firmware program to process the detected inputs to prevent a common firmware error.

Abstract: A deep fat fryer system includes a vat for holding a quantity of cooking medium. A tube or conduit is disposed between a position in the vat corresponding to a lower desired level of cooking medium in the vat and a blower for creating a vacuum in the tube. A pressure sensitive switch is disposed for sensing differences in pressure between the inside of the conduit and the outside of the conduit. The pressure sensitive switch provides an electrically detectable indication of when the difference in pressure between the inside of the conduit and the outside of the conduit is in excess of a predetermined difference in pressure indicative of cooking medium covering the end of the tube disposed in the vat.

Abstract: An automatic system is disclosed which monitors and replenishes hazardous liquids in their holding tanks, as such liquids are typically used in manufacturing processes. The inventive system and method obviate the need for manual surveillance and handling of the hazardous liquids during the detection and replenishment maintenance tasks. In prior practice, maintenance personnel were subjected to dangers from the hazardous liquids and their noxious gases, while the work area (e.g., clean room) in the vicinity of the liquid tanks was also subjected to contamination.

Abstract: A proximity detection system includes a dual mode oscillator for generating a pair of ON and OFF control signals. A sensing circuit including a capacitance device detects the presence of a conductive object, such as a liquid, to cause the oscillator to switch its modes of oscillation.

Abstract: A fluid sampling apparatus is disclosed for withdrawing samples of groundwater or other fluids from a well or other monitoring site. The apparatus preferably includes pump means, conduit means and a wellhead assembly that are substantially permanently installed at such well or monitoring site and are thereby dedicated thereto in order to avoid or minimize cross-contamination of samples from site to site. The apparatus preferably also includes a removable and portable controller means adapted for easy and convenient transportation and connection to such dedicated fluid sampling components at various wells or monitoring sites.The questions raised in reexamination request No. 90/001,494, filed Apr. 18, 1988, have been considered and the results thereof are reflected in this reissue patent which constitutes the reexamination certificate required by 35 U.S.C. 307 as provided in 37 CRF 1.570(e).