Abstract: The present invention provides an electrostatic capacitance type transducer and a method for producing the same, with the ensured sufficient connecting strength and insulation between a movable electrode and a fixed electrode and smooth production. In the electrostatic capacitance type transducer having: a substrate; a movable electrode placed on the opposite side of a space from the substrate and having displacement in relation to the substrate; and a fixed electrode formed on a detecting face of the substrate which is opposite to the movable electrode, an insulation film is formed on the approximately whole surface, including the fixed electrode, of the detecting face of the substrate, in which the substrate and the movable electrode are connected through the insulation film to each other by means of the anode-contact.

Abstract: A sensor apparatus is described that detects and indicates the quantity of cryogenic liquid in a Dewar container independent of the spatial orientation and physical motions acting on the Dewar container. The sensor apparatus comprises a first conductor, preferably positioned adjacent to the container inner shell wall and a second conductor comprising a plurality of axially spaced and concentric conductor bands mounted inside the container in a proximately spaced and a parallel relationship with respect to the first conductor. The second conductor bands divide the first conductor into zones that provide a plurality of distinct and separate capacitors. A computer measures the capacitance of each capacitor and compares the individual capacitance measurements to reference capacitance values corresponding to a known quantity of cryogenic fluid filled in the container at known angles of inclination. The sensor apparatus is also useful as a motion detector.

Abstract: A capacitive fluid pressure transducer is shown formed of a monolithic ceramic body (10) having a cavity located between a diaphragm portion (12) and a base portion (14). Opposed capacitor plates (22, 24) are disposed on opposed surfaces of the diaphragm portion and the base portion. The capacitor plates (22, 24) are formed of palladium oxide/silver having a ratio selected to create a fluid pressure level in the cavity as a result of oxygen evolution incident to the reduction of palladium oxide during the sintering cycle to offset the tendency of the diaphragm to bow inwardly due to shrinkage mismatch of the metal and ceramic materials.

Abstract: A sensor apparatus is described that detects and indicates the quantity of cryogenic liquid in a Dewar container, independent of the spatial orientation and the physical motions acting on the container.

Abstract: The invention concerns rainwater sensors for windshields. In one embodiment, a first, inner, conductive film is applied to the inner surface of the windshield, and a second film, of same size and shape as the first, is applied to the outer surface. However, a narrow strip is removed from the second film, forming a gap which divides the second film into parts 1 and 2. The resulting structure forms two capacitors, namely: (1) inner film plus part 1, and (2) inner film plus part 2. The impedance of one capacitor is monitored. When rain occurs, it falls into the gap between parts 1 and 2, and acts as a resistor, bridging part 1 to part 2. This bridging adds a new impedance in parallel with the first capacitor, thereby changing the effective impedance. This change indicates the presence of rain.

Abstract: A continuous liquid level measuring system having a guarded capacitance probe and related drive circuit for providing accurate level measurements, even when measuring the level of ionic and highly viscous fluids. The capacitance probe has two parallel electrodes, each constructed of a half-tube section, that are separated from each other by an insulated guard wire. The probe is excited by a 1 MHz excitation signal applied across the electrodes. The current through the electrodes is a function of the capacitance between the electrodes, which is affected by the relative permitivity of the surrounding liquid. The effects of highly viscous ionic liquids that adhere to the probe are reduced by exciting the guard wire with a guard signal that is 180.degree. out of phase from the probe's excitation signal. The guard signal changes the electric field existing in the space adjacent the junctions of the two electrodes to reduce any liquid coating effects on the level measurement.

Abstract: A main sensor electrode part 3 and a reference sensor electrode part 4 are deposited in patterns over the surface of a support member 10. A lead-out part 4b of the reference sensor electrode part 4 is extended through an unplated passage 11 of the main sensor electrode part 3 to the upper edge of the support member 10 to form there a terminal part 4a. A portion of the main sensor electrode part 3 is also extended to the upper edge of the support member 10 to form there a terminal part 3a. The support member 10 is deposited all over its surface with an insulating film 12 covering the both sensor electrode parts 3 and 4.

Abstract: The innovation pertains to a device for fastening the housing of a data sensing element which encloses electronic circuits and connecting elements. Data sensing elements of this type are fastened in the wall which encloses the medium to be measured by means of a screw insert. Depending on their function, these data sensing elements may assume a position in which the connection of the connecting lines leading to a control room which is situated at a distance from the measuring point is only possible with great difficulties. This is the reason why the housing should be adjustable axially symmetrically relative to the screw insert. According to the solution suggested, the separable connection between the housing and the screw insert is formed by only one easily accessible screw which penetrates through a clamping disk and by projections which penetrate into a groove of the screw insert.

Abstract: Apparatus for measuring the volume of an electrically conductive liquid held in a confined area includes a tank constructed of electrically conductive, fiber-reinforced composite material having an inside surface and an outside surface. An electrically insulative liner is disposed in the tank against the inside surface thereof to receive and hold the liquid. A voltage source supplies an electrical charge to the tank walls, with ground potential being supplied to the liquid, to thereby develop a capacitance between the tank walls and the liquid. The capacitance varies with variation in the volume of liquid and thus by measuring the capacitance, a measure can be made of the volume of liquid in the tank.

Abstract: A level measuring probe in which all potential leakage paths are closed by concentrically shrinking the outmost diametrical surface of the probe by some mechanical means such as a crimper or rotary swager to provide sufficient force to substantially uniformly deform the ground, guard, and active elements and insulators around the circumference of the probe such that multiple seals are created. A circumferential notch is preferably provided in the active probe element at the point of the crimping or swaging to provide "blowout protection" whereby the active probe electrode is held in place when used in a high pressure vessel. A pressure seal between the electrodes and insulation material is also maintained by using an elastomeric insulator which returns to its original shape after heating or a thin electrode which "gives" a little when the insulator expands radially during heating. The arrangement of the invention thus eliminates the need for costly machined parts and bushings to provide pressure seals.

Abstract: A device is disclosed to measure the level of material within containers, in particular containers in which free-flowing materials having different dielectric constants, for example water and oil, are collected. The device includes a sensor, which is arranged electrically nonconductively fashion on an outer side of the container and forms part of an electric capacitor, and an electrically conducting complementary plate, which is arranged on the inside of container opposite the sensor and spaced therefrom, which, forms another part of an electric capacitor.

Abstract: A system for determining changes in sea level based on the measurement of distance between capacitive elements. The system includes an electrically conductive sphere 17, 117 mounted on an electrically non-conductive buoy 13, 113, positioned a predetermined distance above sea level with the sphere and the sea (earth) acting as capacitive elements separated by the predetermined distance. The system also includes an ion source 25 for imparting charge to the sphere 17, a clock 23, an electrometer 21 for detecting (measuring) the voltage on the sphere at selected clock times. In an alternative embodiment, the ion source and electrometer are replaced with a swept frequency voltage generator 121, an inductor 127, and an ammeter 125. The inductor 127 and the sphere 117 form an LC component. In response to voltages of various frequencies applied to the sphere 117 by the generator 121, the ammeter 125 at each clock time, detects (measures) the current at the resonant frequency of the LC component.

Abstract: A liquid level sensing device for determining the level of a liquid in a liquid confining unit, methods of making and operating the device and a laundry machine using the device are provided, the device comprising a pair of electrode plates disposed in spaced apart relation so as to be adapted to be in a certain position relative to the confining unit and having opposed ends, an electrical circuit connected to the electrode plates for creating a voltage signal therefrom that varies in relation to the level of the liquid in the confining unit relative to the electrode plates, a control for determining the actual level of the liquid from the signal, and a third electrode plate disposed in spaced apart relation to the pair of electrode plates and being adapted to cooperate with one of the pair of electrode plates to provide a reference voltage signal to determine the electrolytic base of the liquid.

Abstract: A system for indicating level of material in a vessel comprising a probe which includes a plurality of electrically discrete probe elements of electrically conductive construction position within a material vessel in a spaced array extending height-wise of the vessel. Each probe element has electrical characteristics which vary as a function of proximity of material thereto within the vessel. In one embodiment, the probe elements comprise capacitive elements responsive to varying dielectric characteristics as material approaches each element. In another embodiment, having particularly utility in fuel level sensing applications, the probe elements comprise resistance elements responsive to cooling through immersion in fuel for varying voltage drop thereacross. Electonic circuitry is coupled to the several probe elements for detecting material level as a function of electrical characteristics of the probe elements.

Abstract: A system and method for selecting one of a plurality of liquid supply receptacles as a source of supply for a liquid dispensing apparatus is disclosed. As liquid is withdrawn from the supply receptacle the dielectric constant of the liquid is sensed in order to detect any undissolved gases (i.e., bubbles) which are present in the liquid. The presence of bubbles within the liquid indicates that a supply receptacle has become empty or indicates a failure of components associated with one of the supply receptacles. Upon the detection of undissolved gases within the liquid withdrawn from a supply receptacle, the present invention causes another liquid supply receptacle to be selected as a source of supply for the liquid dispensing apparatus.

Abstract: In a preferred embodiment, a capacitive sensor element which includes a metal plate which is flat and smooth and hard-coated with a dielectric material, such as an oxide. The dielectric surface slidingly contacts a smooth metal plate, such as hardened steel, with the capacitance of the sensor element varying with the area of contact of the two plates. Aluminum oxide provides an excellent dielecric surface. The sensor may be constructed in a number of configurations and can be ruggedly constructed for harsh environments. In a further embodiment, a metal member having a hard-coated dielectric material on the surface thereof is partially immersed in a conductive liquid to form a capacitive liquid level sensing element.

Abstract: A fluid level gauging probe having a flexible transmitter wherein the flexible transmitter includes a first flexible electrically conductive conduit flexibly and substantially coaxially supported within a second flexible conduit. The second flexible conduit includes an electrically conductive probe conduit portion forming an electrical capacitance member with the first conduit. Non conductive spacers are provided for flexibly and substantially coaxially supporting the first flexible conduit within the second flexible conduit. Non conducting locating pins are radically disposed through longitudinal slots in the first and second flexible conduits for the attaching the flexible transmitter to a probe housing and for maintaining the first and second flexible conduits in a substantially fixed longitudinal relationship when the flexible transmitter is flexed.

Abstract: A device that determines liquid level or volume by means of charging a plurality of capacitors in sequence. Each capacitor is charged for a fixed time interval. The voltage level obtained is a function of the liquid level and is compared with a known voltage to obtain an output signal that can be used to represent liquid depth. The capacitors are formed by two concentric tubes, one inside the other in a spaced relationship. The tubes reduce the effect of sloshing in the tank, resulting in a more stable reading. To measure volume or level in an irregular shaped tank, the capacitors can be arranged in a non-linear manner. The device has no moving parts to wear out and thus results in higher reliability and longer life.

Abstract: A capacitive probe for use in a system for remotely measuring the level of fluids. The probe is continuously charged and discharged. The discharge current from the probe is measured and converted to a corresponding voltage rerepresenting the level of fluild. The voltage is then supplied to an indicating device. One embodiment of the probe includes first and second spaced supports which maintain a plurality of spaced parallel wire electrodes which form two capacitive plates. In a further embodiment of the probe, the wire electrodes are positioned on an integrally formed support.

Abstract: A device measures or controls a change of a level or a variation in a change of a level between several points. The device includes closed vessels (2) placed respectively at each of the points. The vessels are partially filled with a liquid (53) and are connected by liquid pipes emerging in their lower portion so as to form a liquid circuit (31) and by gas pipes emerging in their upper portion so as to form a gas circuit (36). Each vessel is equipped with a capacitive proximity sensor (11) placed above and at a distance from the upper surface (54) of the liquid which it contains and which provides a signal with respect to position in the vertical direction of a zone of the upper surface of the liquid in the vessel. A device comprises the signals provided by the sensors so as to be able to provide data with respect to the vertical position of the vessels and, consequently, with respect to the points relative to one another or relative to a reference vertical position.

Abstract: A portable level sensing device includes an audible alarm and a visual alarm (preferably LEDs) for signalling when a predetermined level has been sensed by a capacitance proximity switch. The device is designed for use in tank cars, ships, barges, and tank trucks, and includes a graduated rod and a threaded coupling to allow one to quickly and easily set the capacitance proximity switch at the proper level in a tank. The device includes an weather-tight housing and is intrinsically safe for use in hazardous area classifications Class I, Division 1, Groups A, B, C, & D. The device can be coupled in a pressuretight manner to the tank to prevent the escape of fumes during use.

Abstract: The present invention relates to apparatus for measuring the level and/or the volume of liquid contained in the tank. The apparatus being of the type comprising a capacitive probe including at least two generally vertical parallel separate main plates for immersing in the liquid, and capacitance-measuring means having a detection input and a ground, the detection input being connected to a first one of the main plates and the ground being connected to the second main plate, wherein the first plate is surrounded by a guard ring.

Abstract: A liquid level sensing device for determining the level of a liquid in a liquid confining unit, methods of making and operating the device and a laundry machine using the device are provided, the device comprising a pair of electrode plates disposed in spaced apart relation so as to be adapted to be in a certain position relative to the confining unit and having opposed ends, an electrical circuit connected to the electrode plates for creating a voltage signal therefrom that varies in relation to the level of the liquid in the confining unit relative to the electrode plates, a control for determining the actual level of the liquid from the signal, and a third electrode plate disposed in spaced apart relation to the pair of electrode plates and being adapted to cooperate with one of the pair of electrode plates to provide a reference voltage signal to determine the electrolytic base of the liquid.

Abstract: A system for indicating the level of material in a vessel as a function of material capacitance comprising a resonant circuit including a capacitance probe adapted to be disposed in a vessel so as to be responsive to variations in capacitance as a function of material level. An oscillator has an output coupled to the resonant circuit and to a phase detector for detecting variations in phase angle as a funciton of probe capacitance. Level detection circuitry is responsive to an output of the phase detector and to a reference signal indicative of a level of material for indicating material level as a function of a difference between capacitance at the probe and the reference signal. In the preferred embodiments of the invention disclosed, an automatic calibration circuit adjusts the resonance characteristics of the parallel resonant circuit in a predetermined or preprogrammed manner during a calibration operation to a point indicative of the predetermined reference material level.

Abstract: An improved capacitance bridge type liquid level control system for use in refrigeration applications is disclosed which provides improved apparatus for sealing the probe in its mounting and for insulating same against the condenser reservoir stand pipe in which it is mounted. Improved sealing between the probe and probe body is accomplished through an annular PTFE seal which when compressed pushes inwardly to seal a tubular PTFE insulation against annular ridges in the side of the probe rod proper. The improved probe rod shape also maintains a proper stabilized axial alignment between the probe rod and the probe body.

Abstract: A non-intrusive fluid level detector including a single point capacitive sensor mounted on the outside surface of a receptacle such that capacitive principles can be utilized to sense the level of a liquid contained within the receptacle. The sensor assembly is disposed in a substantially fixed position on the exterior wall of the receptacle wherein the dielectric effect of the liquid changes the effective capacitance of the sensing capacitor as the liquid rises and falls within the receptacle. This change in effective capacitance is detected by electronic circuitry included in the detector device. In one embodiment, the fluid level detector is directly mounted to a completely non-conductive receptacle. In another embodiment, the fluid level detector is mounted to a non-conductive window which is an integral part of a receptacle fabricated out of a conductive material.

Abstract: A capacitive level gauge for placement in a container (12) determines the level of substance (14) in the container (12). The gauge (10) includes a measurement capacitor (C1) for measuring level and a reference capacitor (C2) for determining dielectric constant of the substance (14). A controller (34) is responsive to the capacitors (C1, C2) for producing a level signal which simultaneously indicated the level and dielectric constant of the material. The level signal includes a frequency which is representative of dielectric constant and a pulse width representative of level. The gauge (10) supports a first pair of parallel conductive members (26, 28) to establish the measurement capacitor (C1) and a second pair of parallel conductive members (28, 32) spaced along the gauge and below the measurement capacitor (C1) to establish the reference capacitor (C2).

Abstract: A capacitor for a fluid level sensor that has first and second elongated expandable capacitor plates mounted in spaced relationship with respect to each other in a container to form a capacitor for measuring data representing the liquid in the container, the capacitor plates being continuously expandable from a first length to a second length with a given change in the shape of the container. Thus, the capacitor compensates for the change in container shape.

Abstract: A storage installation which is capable of storing a variety of free-flowing materials, both conductive and non-conductive, includes a level sensing device which may be disposed either exteriorly or interiorly thereof. The device has either one or a plurality of level sensor and sensor circuit pairs which are preferably disposed vertically within a non-electrically conducting tube which may be hermetically sealed from contact with the stored material. The level sensors comprise respective sensing capacitors, each having effectively a single plate construction. Grounded electrical contacts, if relatively adjacent, may comprise the other side of the effective sensing capacitor. Electrostatic force lines flow outward from the sensing capacitor(s), and are differentially interfered with by the presence or absence of materials or objects to be sensed. Such interference affects the dielectric constant of the respective sensing capacitor, which can in turn be detected to drive a level indicator display.

Abstract: A washer fluid monitor comprising a pair of electrically conducting probes projecting downward into a washer fluid reservoir and incorporated into part of the positive feedback loop of a Wien bridge oscillator. One of the probes is grounded; and the Wien bridge oscillator is modified with an additional capacitor isolating the other probe from the DC supply and intermediate voltages so that it is essentially grounded at the oscillator frequency to greatly reduce or eliminate ionic currents in the washer fluid and resulting probe degradation without the need for an isolating transformer.

Abstract: A capacitive level gauge for placement in a container (12) determines the level of substance (14) in the container (12). The gauge (10) includes a measurement capacitor (C1) for measuring level and a reference capacitor (C2) for determining dielectric constant of the substance (14). A controller (34) is responsive to the capacitors (C1, C2) for producing a level signal which simultaneously indicated the level and dielectric constant of the material. The level signal includes a frequency which is representative of dielectric constant and a pulse width representative of level. The gauge (10) supports a first pair of parallel conductive members (26, 28) to establish the measurement capacitor (C1) and a second pair of parallel conductive members (28, 32) spaced along the gauge and below the measurement capacitor (C1) to establish the reference capacitor (C2).

Abstract: An electrostatic capacitance type detecting device which includes a first electrode placed in the proximity of an object to be measured, a second electrode placed in the proximity of the first electrode, a film like dielectric member interposed between the first and the second electrodes, a first resistor one end of which is connected to one end of the first electrode, a second resistor one end of which is connected to one end of the second electrode, an a. c. signal generator connected to the other ends of the first and the second resistors and to the ground and a phase difference detecting means connected to the first and the second electrodes.

Abstract: A device for measuring the quantity of light in a tank is disclosed, including three level sensors housed within a tank in a predetermined relative position. Alternative processors are disclosed for processing information supplied by the level sensor, wherein the information depends on the liquid level sensed by each of the sensors. An indicator, controlled by the processor, indicates the quantity of liquid contained in the tank.

Abstract: A capacitive sensor is constructed to eliminate electrical conduction through a liquid being measured. The electrical conduction in the liquid occurs between the plates of the reference and measuring capacitors. The capacitive plates which are spaced from the common capacitive plate to form the reference and measuring capacitors are of unitary construction and formed from anodized aluminum. The anodization forms an insulated surface which prevents conduction between the electrodes through the liquid. A ratio taken between the measuring capacitor and reference capacitor is therefore indicative of the level of the liquid within the gap of the measuring capacitor and is independent of the conductance of the liquid and its dielectric constant. Such a probe is particularly useful in applications where the liquid undergoes indeterminable changes in conductivity such as a lubricant which becomes contaminated by metallic particulates.

Abstract: A capacitance liquid level or volume sensing and touch control system for use with a conductive liquid having some isolation from and a capacitance to ground in accordance with its volume, is characterized by a circuit for cyclically charging the liquid a predetermined amount and then discharging it for a fixed time through an impedance. The extent of discharge of the liquid at the end of the fixed time is sensed, and is used to generate a signal representative of the volume of the liquid and its level. The system also has a capacitance touch control circuit, which generates an output signal when a sensor probe is touched or closely approached by a user. The signals from the capacitance liquid level sensing circuit and the touch control circuit are applied to a discriminator circuit which, when a signal representative of a sensed minimum volume of liquid is present, enables outputs from the touch control circuit to operate peripheral equipment, such as a pump for recirculating the liquid.

Abstract: A storage installation which is capable of storing a variety of free-flowing materials, both conductive and non-conductive, includes a level sensing device disposed preferably vertically therein. The device has a plurality of level sensor and sensor circuit pairs disposed vertically within a non-electrically conducting tube which is hermetically sealed from contact with the stored material. The level sensors comprise plural sensing capacitors, each having cylindrical upper plates and grounded lower plates. Electrostatic force lines from the sensing capacitors penetrate walls of the sealed tube, and are differentially interfered with by the presence or absence of material to be sensed. Such interference affects the dielectric constant of the respective sensing capacitor, which can in turn be detected by a relatively small corresponding circuit housed directly in the tube. DC signals from the respective circuits are brought out of the tube to drive a level indicator display.

Abstract: Robotic liquid separation operates independently of liquid volume, viscosity, or optical characteristics, by sensing changes in the dielectric constant of the liquid as it is being drawn through a cannula. The cannula has electrodes which form a sensing capacitor for detecting the changes in the liquid dielectric constant as the liquid is drawn therethrough.

Abstract: A capacitance probe and method of probe manufacture for material level sensing systems and like applications. The probe includes a probe rod, a tubular guard coaxially surrounding the rod intermediate the rod ends, and insulation material formed as an integral piece in an injection molding operation surrounding the rod between the rod and guard and also surrounding and radially overlapping axially spaced ends of the tubular guard. One end of the rod and a portion of the guard intermediate its ends are exposed through the insulation material. The molded assembly is captured within a nipple or the like for mounting to a material vessel such that the exposed surfaces of the rod and guard are disposed internally of the vessel for capacitance coupling to material therewithin.

Abstract: An improved capacitance bridge type liquid level control system for use in refrigeration applications is disclosed which provides improved apparatus for sealing the probe in its mounting and for insulating same against the condenser reservoir stand pipe in which it is mounted. Improved sealing between the probe and probe body is accomplished through an annular PTFE seal which when compressed pushes inwardly to seal a tubular PTFE insulation against annular ridges in the side of the probe rod proper. The improved probe rod shape also maintains a proper stabilized axial alignment between the probe rod and the probe body.

Abstract: An overfill sensing system uses a capacitive sensor (12) on the interior of a tank for sensing the presence of a liquid to cease the filling process. The capacitive sensor (12) includes a sensing capacitor (16) and a reference capacitor (18) on separate arms of a bridge circuit (22). An oscillator (28) supplies an AC signal to the bridge circuit (22) divided by a variable resistor (30 ) to balance the bridge (22). A comparator (24) receives the output on each arm of the bridge (22) to sense a differential therebetween. When a liquid reaches the sensing capacitor (16), the capacitance changes from a predetermined capacitance, thereby changing the differential. A control circuit (14) is responsive to the differential at the output of the comparator (24) for visually indicating the status of the filling process and ceasing the filling process from the filling facility when a liquid has been detected.

Abstract: A probe comprises a plurality of longitudinally extended conductors forming a probe electrode, a laterally displaced ground electrode and two laterally displaced active guard electrodes interposed between the probe electrode and the ground electrode. The conductors are surrounded by solid insulation and the probe guard electrodes are driven at substantially the same potential as the probe electrode. The probe is utilized to measure the condition of materials in which the probe is immersed.

Abstract: Sensor for an apparatus for measuring the level and/or the quantity of a liquid medium in a vessel, for example a pressure vessel, provided with a carrier which may be mounted in the wall of the vessel, a first pipe fastened to the carrier and a second pipe positioned concentrically and insulated within the first pipe, which second pipe may be connected through a bushing member positioned in the carrier, wherein a conductor is wound at least locally on the first pipe, which conductor is insulated with respect to the first pipe and may be connected through a bushing member positioned in the carrier.

Abstract: A calibration apparatus and associated method for the measurement of valuable fluids in storage or at the point of transfer. More particularly, a calibration apparatus and method for use with capacitive liquid level measurement systems.

Abstract: A characterized inner electrode for a capacitive fuel-gauging probe comprises several discrete tubular sections of different diameters which are joined together end-to-end by metal coupling pieces. One or more of the tubular sections has two regions of different diameters that are continuous with one another, the smaller diameter region being formed by swaging down from the larger diameter region. The coupling piece has two shoulders to which the ends of the tubular sections are electron-beam welded. The coupling piece also has respective annular recesses into which a low viscosity adhesive is introduced via overlying apertures in the tubular sections after welding, so as to form an adhesive joint between the coupling piece and the tubular sections. The ends of the coupling piece are a close fit within the tubular sections and extend into them by a distance at least twice the diameter of the coupling piece.

Abstract: A control device for a corrosion testing apparatus includes an airtight air saturation tower which is adapted to contain a liquid. A heater is provided in the tower to heat the liquid. A sensor is provided adjacent a wall of the tower, to sense an abnormal condition in the tower. The sensor can be adapted to measure the presence of liquid in the tower adjacent the sensor or the temperature of a wall of the tower. A control device is provided for shutting off the heater when the sensor detects an abnormal condition in the tower.

Abstract: A gauge for measuring the height of a liquid in a vessel comprises a measuring electrode (M) and a compensation electrode (R) in the vessel, and a circuit which measures the capacitance C.sub.M of the measuring electrode and the capacitance C.sub.R of the compensation electrode, each with respect to a wall of the vessel as counter-electrode, using the liquid in the vessel as dielectric. The quotient C.sub.M /C.sub.R varies with the height of the liquid in the vessel. The measuring electrode and the compensation electrode are parallel and of the same length, but differ in surface area and shape to such extent that such quotient varies as a linear function of the height of the liquid in the vessel.

Abstract: A device for determining the position of an interface between different fluids in a tank or container is provided. This device has a plurality of cells, placed one below another and mounted on a structure which is placed in the tank or container, each cell consisting of three electrically conductive elements, isolated from each other, the first element of each cell being adapted to be connected to an AC signal source, the third element of each cell being adapted to be connected to zero potential, and the second element of each cell being adapted to be connected to a receiver for detecting the transmitted AC signal.

Abstract: A fuel volume measuring system for an automotive vehicle in which fuel volume detection signals are simply averaged during a relatively-short averaging time period at regular measuring cycles when the vehicle is being refueled, and further weight-averaged or moving-averaged at regular measuring cycles when the vehicle is running. Therefore, fuel volume can be indicated quickly at a high response speed when the vehicle is being refueled and additionally fuel volume fluctuations can be minimized when the vehicle is running. Further, the system according to the present invention discloses the method of detecting the state where the vehicle is being refueled on the basis of the fact that the difference between at-least one of the current data signal indicative of fuel volume and at-least one of the preceding data signal indicative of fuel volume exceeds a predetermined value.

Abstract: A sensing apparatus including: a first electrode member; a second electrode member arranged at opposing positions a predetermined distance away and electrically isolated from the first electrode member; and an electric circuit connected to the first and second electrode members. The first and the second electrode members are operatively connected by an impedance formed between the first and the second electrode members in response to existence of a substance to be sensed between the first and the second electrode members. The electric circuit outputs a signal in response to the impedance. The sensing apparatus is applicable for detecting, for example, the level of a liquid in a vessel.

Abstract: A capacitive level gauge for placement in a container (12) determines the level of substance (14) in the container (12). The gauge (10) includes a measurement capacitor (C1) for measuring level and a reference capacitor (C2) for determining dielectric constant of the substance (14). A controller (34) is responsive to the capacitors (C1, C2) for producing a level signal which simultaneously indicated the level and dielectric constant of the material. The level signal includes a frequency which is representative of dielectric constant and a pulse width representative of level. The gauge (10) supports a first pair of parallel conductive members (26, 28) to establish the measurement capacitor (C1) and a second pair of parallel conductive members (28, 32) spaced along the gauge and below the measurement capacitor (C1) to establish the reference capacitor (C2).