Abstract: A capacitive liquid level indicator having a capacitive sensor array superposed on each side of a dielectric substrate, wherein the sensor signal detection electronics are located immediately adjacent each capacitive sensor. These provisions result in high sensitivity of detection of submergence in the liquid, as well as essentially eliminating parasitic electric fields. The preferred capacitive sensors are interdigitated capacitors, and the preferred sensor signal detection circuit is an RC bridge and a comparator, wherein the comparator senses a voltage difference in the RC bridge between a sensor resistor and sensor capacitor of a first leg thereof and a reference resistor and reference capacitor of a second leg thereof. It is preferred for the capacitive liquid level indicator to be coated with a low dielectric conformal coating to thereby insulate the electronic components (inclusive of the capacitive sensors) thereof with respect to the liquid into which it is submerged.

Abstract: A liquid transfer device for an analysis unit includes a transfer needle having a tip, and a capacitive liquid level detector for detecting immersion of the tip of the needle into an analysis liquid by detecting a change in capacitance between a signal electrode and a counter electrode. The analysis liquid is contained in a vessel. The capacitive liquid level detector includes a signal electrode, a counter electrode, and a detection circuit connected to the signal electrode and the counter electrode. The detection circuit detects a change in capacitance between the signal electrode and the counter electrode. A temperature dependent detection resistor is disposed adjacent the tip of the liquid transfer needle. The tip of the liquid transfer needle and the temperature dependent detection resistor are movable into and out of the analysis liquid. The detection circuit includes a current supply for supplying current to the detection resistor.

Abstract: A digital liquid level sensing apparatus for detecting variations in the dielectric of a substance being sensed. The apparatus includes a capacitive element array including a plurality of individual (i.e., segmented) input plates positioned along an axis of measurement of a fluid to be detected. The array also includes a common output plate having a length sufficient to span the entire accumulated length of the input plates. A controller sequentially applies DC excitation pulses to the input plates which cause a series of output currents to be coupled onto the output plate. The output currents are input to a current-to-voltage amplifier which generates a series of corresponding analog output voltages. The analog output voltages are then input to a peak voltage detector circuit to generate a series of peak voltage signals representative of the magnitudes of the analog output voltages.

Abstract: A digital liquid level sensing apparatus for detecting variations in the dielectric of a substance being sensed, to thereby provide a signal indicative of the level of the liquid being sensed in relation to a known full level. The apparatus includes a reservoir having an output plate and an input plate assembly associated therewith. The input plate assembly includes a plurality of independently electrically excitable input plates which transmit a signal through the liquid being sensed to the output plate. The signals from the output plate are processed and a determination is made as to the level of liquid in the reservoir relative to a known full level. If the input plate assembly is located against the exterior surface of one wall of the reservoir, then both of the interior and exterior portions of that particular wall should be devoid of any metallic surface. In an alternative embodiment, a discardable interior reservoir is provided which fits nestably within the reservoir of the sensor.

Abstract: Switching member SW20 which receives detection signals for detecting capacitance outputted from a control part 35, controls each of switches so as to measure capacitance between electrodes positioned adjacently (an electrode TE1 and an electrode TE2, and so on) before measuring capacitance of measuring object. Capacitance initially measured between the adjacent electrodes are stored in a storing circuit 30. The initial capacitance are averaged to calculate an averaged initial value. Upon calculating the averaged initial value, correction values which represent difference between the averaged initial value and the initial capacitance are calculated. Actual measured values are corrected using the correction values when level of measuring object is measured. It is therefore possible to measure level of measuring object without influence of floating items or the like with stability, because level measurement is conducted by utilizing capacitance measured between adjacent electrodes.

Abstract: Device for determining quantities of products contained in adjacent ones of plural reservoirs, by using a capacitive arrangement. According to the invention, two electrodes of the capacitive arrangement are disposed between two reservoirs and are in each case either sending electrodes to which a signal is applied, or receiving electrodes which transmit a signal. By virtue of this arrangement, it is possible to reduce parasitic coupling between different capacitors of the capacitive arrangement.

Abstract: In order to monitor the consumption of a normally electrically conductive product contained in a reservoir made of electrically insulating material, a measurement procedure is defined according to which there is taken off a measurement signal in response to an excitation signal applied to a storage cavity in this reservoir, this signal being such that a characteristic, such as the voltage, of the measurement signal varies substantially with the quantity of product contained in the cavity, and with a utilisation parameter of this product. A procedure for determining this utilisation parameter and a processing procedure giving an item of information on the quantity of product remaining in the reservoir as a function not only of the said characteristic but also of the instantaneous value of the utilisation parameter, are also defined. In the field of printing, this parameter can be the density of printing of the printed pages, or the temperature.

Abstract: A sewer basin has a tube mounted longitudinally in the basin to isolate the level sensing elements from particulate and non-soluble materials present in the basin which could contaminate the elements, which are used for selectively activating a pump in the basin. The liquid level in the tube is kept in equilibrium with the liquid outside of the tube by an aperture below the normal low liquid level. A filter is provided in the tube between the aperture and the level sensing elements. The filter is formed by a stack of filter elements mounted on an axial post extending into the tube from a bottom end cap. The elements are limited in their axial mobility on the axial post.

Abstract: The subject matter of the present invention is a method and a device for capacitive liquid level measurement which are particularly suitable for determining liquid level between adhesive media 10, 11 of different conductivity. The known sensor principle is based on the fact that the environmentally dependent capacitance is measured between neighboring electrodes 13, 4; 4, 5; 5, 6 of a rod-shaped probe 1. According to the invention, the probe 1 has electrodes 4, 5, 6, 13 with covers 7 of different thicknesses d.sub.i. The effective thickness d.sub.s /.epsilon..sub.s of an insulating pollutant film 14 can then be determined by capacitance measurements between at least two pairs of electrodes 4, 5, 6, 13. The influence of a conductive pollutant film 14 on the capacitance signal can be eliminated by selection of at least one suitable measuring frequency.

Abstract: A flow control device for a toilet to prevent flooding upon obstructing of a waste outlet of a toilet bowl. The device includes a sensor assembly mounted on a clip held over a rim of the toilet bowl so as to hold the sensor assembly in a predetermined position within the toilet bowl. The clip may include adjustable elements thereon to enable the height of the sensor assembly to be adjusted, depending on the size and type of toilet in which it is affixed. If water bridges contacts on the sensor assembly, an electrical circuit is completed, and a solenoid is actuated to close a normally opened valve to shut off running water to the water tank of the toilet. The present invention is an easily-added-on, simplified device for use with a toilet bowl to prevent flooding, if the waste outlet of the toilet bowl is blocked for any reason.

Abstract: A system for preventing a toilet bowl from overflowing is disclosed. The system includes a sensor mounted to the toilet bowl at a location above a normal water level for the toilet bowl. The sensor is operative to sense the water level in the toilet bowl, and generates a warning signal if the level is above the normal level. The system further includes a valve connected to the water conduit feeding the toilet bowl, the valve being displaceable to respective open and closed positions. A drive assembly is connected to the valve to drive the valve to the open and closed positions. The system still further includes a processor electrically coupled with the sensor and the drive assembly to enable the drive assembly upon receiving the warning signal from the sensor.

Abstract: Described herein is an alarm system for use with a `bag-in-box` arrangement (10) which is used to collect effluent from a processing apparatus (20). The alarm system comprises a chamber (50) located between the processing apparatus (20) and the `bag-in-box` arrangement (10) which includes a level sensor (52) which indicates that the `bag-in-box` arrangement (10) has been overfilled by a predetermined amount and is ready for changing.

Abstract: A time domain reflectometry linear position sensing system having a transmission line with a helically wound inductor and a ground conductor. The transmission line includes a movable member that electrically connects with the ground member and which extends along the inductor from a first end a distance that depends on the position of an object whose position is being determined. A signal generator applies pulses between the first end and the ground conductor and a receiver receives reflections of those pulses. The delays between the applications of pulses and the receptions of reflections depend upon the position of the object. A position determining circuit determines the position of the object based upon the delays, beneficially by using sing-around. Beneficially, a third member extends a predetermined distance along the inductor from a second end. That third member provides a reference delay that can improve the system accuracy.

Abstract: A capacitive level detection system provides a highly accurate determination of liquid level within a container. The primary sensor is an elongate capacitive probe positioned vertically within the container so that a lower portion of the probe is in liquid and an upper portion of the probe extends above the surface of the liquid. A capacitive liquid reference sensor is proximate the lower end of the probe, and a capacitive gas reference sensor is proximate the upper end of the probe. A controller is provided for driving each of the sensors with an electrical signal and reading a resultant value corresponding to the capacitance of each of the sensors. The controller is configured to enable the system to be calibrated prior to installation by placing each of the sensors in a calibration or identical medium, reading sensor values corresponding to capacitances for each of the sensors, and calculating and storing calibration values based on the sensor values.

Abstract: A method for determining an optimized solution of positions for N liquid surface sensors used to gauge quantity of liquid in the container, comprising the steps of:a) defining geometric limits of the container in terms of coordinates of a three axis (x,y,z) reference coordinate system assigned to the container;b) defining a chromosome structure for an individual, wherein said chromosome structure identifies a solution in terms of position data of the N sensors;c) determining a population of individuals wherein each individual in said population is a possible solution within said geometric limits; each individual having a respective chromosome; andd) executing a genetic algorithm on said population to identify a solution that meets a performance criteria as measured by a predetermined cost function.

Abstract: The invention relates to an apparatus for determining the condition of a fluid in a space, comprising: a measuring electrode extending inside the space; a second electrode placed in the space; and a measuring circuit for measuring the impedance between the measuring electrode and the second electrode and calculating the condition from the impedance, wherein the measuring electrode extends at least partially uncovered in the space.According to a preferred embodiment the apparatus is therefore provided with a measuring circuit which is adapted to measure the ohmic impedance between the measuring electrode and the auxiliary electrode. As stated, this provides the option of measuring the impedance of the substance present in the vessel so that with determined material properties it is possible to arrive at a better and more accurate measurement result.It is pointed out herein that the present electrode also enables determining of the capacity between electrode and second electrode.

Abstract: An apparatus (50, 100, 150) for sensing a surface level (20) of fluid (12) includes a generally cylindrical central conductor (16, 102, 152) for connection to a pulse signal source (26) with a reduced diameter end (28, 104, 154) and an opposite end (24, 124, 168); a generally tubular outer conductor (14) concentric with the central conductor for connection to the pulse signal source and having one open end (32) adjacent the central conductor reduced diameter end and an opposite open end (18) adjacent the central conductor opposite end, the central conductor and the outer conductor forming a transmission line for pulse signals generated by the pulse signal source and a cavity (C) between an interior wall surface of the outer conductor and an exterior surface of the central conductor; a non-metallic seal (54) mounted at the outer conductor open end for sealing the cavity, the central conductor reduced diameter end extending through a central aperture (52) formed in the seal; a circuit board (58) for mounting th

Abstract: A system for preventing a toilet bowl from overflowing is disclosed. The system includes a sensor mounted to the toilet bowl at a location above a normal water level for the toilet bowl. The sensor is operative to sense the water level in the toilet bowl, and generates a warning signal if the level is above the normal level. The system further includes a valve connected to the water conduit feeding the toilet bowl, the valve being displaceable to respective open and closed positions. A drive assembly is connected to the valve to drive the valve to the open and closed positions. The system still further includes a processor electrically coupled with the sensor and the drive assembly to enable the drive assembly upon receiving the warning signal from the sensor.

Abstract: A high-sensitivity capacitive oil deterioration and level sensor includes a conductive housing member with an inner surface defining a ground electrode and conductive inner member with an outer surface defining a measuring electrode. The housing member is adapted to provide a fluidic connection between an oil container and a gap between the ground electrode and the measuring electrode. The sensor also includes electronics adapted to employ this capacitor geometry to generate signals indicative of a degree of deterioration and a level of the oil within the gap.

Abstract: A machine tool has a rotatably mounted part and a rotary leadthrough connected thereto, through which a fluid can be delivered to the rotatably mounted part. The rotary leadthrough further comprises an outlet from which leaking fluid emerges in the event of a leak in the rotary leadthrough. The outlet is connected to a fluid sensor which detects the emerging fluid and reports the leak.

Abstract: A secondary seal assembly is used with a process instrument including a probe assembly and an electric housing assembly. The probe assembly includes an adaptor receivable in an opening of a process vessel, a probe extending through the adaptor into the process vessel, and a primary seal between the probe and the adaptor. A probe terminal provides an electrical connection between the probe and the electric housing assembly. The secondary seal comprises an elongate extension housing adapted to be mechanically connected at one end to the adaptor and at another end to the electric housing assembly. A shaft insert is received in the extension housing having a terminal at each of opposite ends, a first terminal for providing an electrical connection to the electric housing assembly and a second terminal for providing an electrical connection to the probe terminal. A seal between the shaft insert and the extension housing provides a secondary seal to the process vessel.

Abstract: A sensor assembly for measuring characteristics of motor oil in a vehicle includes a housing adapted to be mechanically coupled to a vehicle for receiving motor oil of the vehicle and at least one capacitive sensor including sensing electrodes positioned relative to the housing to measure characteristics of motor oil between the sensing electrodes. The sensing electrodes are coated with a soot build-up inhibiting coating which, in a preferred embodiment, is a silicone coating. The at least one capacitive sensor include an oil level sensor and an oil deterioration sensor in a preferred embodiment.

Abstract: A sensor assembly includes a tilt sensor, an oil level sensor, an oil temperature sensor and an oil deterioration sensor, as well as associated output signal conditioning electronics integrated within a common assembly. The sensor assembly is configured to receive a volume of motor oil proportional to a total volume of oil in an engine. The oil level sensor, oil temperature sensor and oil deterioration sensors include electrodes which are completely or partially immersed in the volume of motor oil depending upon the total volume of oil in the engine. The tilt sensor includes only two electrodes both of which are at least partially immersed within a controlled volume of dielectric fluid which is physically and electrically isolated from the volume of motor oil. One of the electrodes of the tilt sensor is completely immersed in the controlled volume of dielectric fluid independent of an angle of the tilt sensor relative to a vector representing forces such as gravity applied to the tilt sensor.

Abstract: A sensor detects when a probe contacts liquid in a container due to a change in frequency of a probe oscillator. The sensor can have its output compared to a reference level to determine the presence or absence of liquid wherein the reference level is changed to follow the output of the detector. In one embodiment, it can be determined that liquid has been contacted when a count has been reached several times in a row (the count being a function of the probe output and changeable). In another embodiment of the invention, it can be determined that liquid has been contacted when a count has been reached within a certain threshold several times in a row, while still having the reference count change to follow the probe output (regardless of the threshold). A digital counter can be provided to determine the frequency of the probe oscillator. A reference counter can also be provided to tune the count (frequency) from the probe oscillator counter to thereby compensate for drift.

Abstract: A fluid sensor (100) senses a level of fluid (20) in a receptacle (10). The fluid sensor comprises a detector assembly (200) for detecting fluid and comprises sensor circuitry. The detector assembly comprises a detector body (201) comprising an electrically insulative material and defining first and second surfaces (210, 220) in a predetermined spaced relation. The detector body defines a space (250) between the first and second surfaces and defines a port (255, 257) for allowing fluid to pass in the space between the first and second surfaces. The detector assembly also comprises first and second conductive layers (212, 222) deposited over at least a portion of the first and second surfaces of the detector body, respectively. The sensor circuitry is conductively coupled to at least one of the first and second conductive layers for generating an electrical signal based on whether fluid is present in the space between the first and second surfaces.

Abstract: A proximity sensing apparatus comprising a capacitor and means for detecting the change in capacitance of the capacitor. The capacitor comprises two capacitive elements that are insulated from each other and are relatively movable. With at least one of the capacitive elements formed from an electrically conducting liquid. The capacitance detecting means operate as a switch in response to the change in capacitance producing a binary output. This output being combined with a series of other outputs from a series of such proximity sensors to form an apparatus to determine position of an object, particularly a liquid level.

Abstract: A pump control system which can distinguish between water and oil so that a pump can be controlled to pump water and deactivated before oil is pumped. Sensing is accomplished by a pair of capacitive sensors, one located above the other in a vessel in which water accumulates. A dual mode frequency oscillator is associated with each sensor. Each sensor reacts to the dielectric constant of the liquid at the sensor by changing its capacitance, to thus detect the presence of a conductive substance, such as a liquid, to cause the sensor's oscillator to switch its mode of oscillation. The dual mode oscillator of each sensor selectively generates a control signal having two different duty cycles. As the dielectric constant of the liquid medium is sensed, a logic circuit interposed between the sensors allows the output of each sensor to be turned off when only the lower sensor is in water. The circuit turns on the pump only when both sensors are in water and the pump remains on until both sensors are out of water.

Abstract: A level detector circuit for detecting a level of immersion of an elongated probe within a liquid. The level detection circuit includes a first set of transistors. One of these transistors charges an elongated probe and a second charges a capacitor. A reference current source provides a reference current based on the charging current provided to the elongated probe by the first transistor and an additional transistor which also charges the probe at a rate such that the voltage on the capacitor and the probe are maintained the same. A monitoring circuit develops an analog level signal based on the current provided by the reference current source. This analog level signal is converted by the combination of an analog to digital circuit and a microprocessor for providing a pulse frequency modulated communications signal corresponding to the analog level signal which in turn is related to the length of the probe immersed within the liquid.

Abstract: A level detector or proximity detector for materials capable of sensing through plastic container walls or encapsulating materials is of the sensor. Thus, it can be used in corrosive environments, as well as in a wide variety of applications. An antenna has a characteristic impedance which depends on the materials in proximity to the antenna. An RF oscillator, which includes the antenna and is based on a single transistor in a Colpitt's configuration, produces an oscillating signal. A detector is coupled to the oscillator which signals changes in the oscillating signal caused by changes in the materials in proximity to the antenna. The oscillator is turned on and off at a pulse repetition frequency with a low duty cycle to conserve power. The antenna consists of a straight monopole about one-quarter wavelength long at the nominal frequency of the oscillator.

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 probe for use in time domain reflectometry includes a body having a conductive portion and an insulated portion. A conductive loop is provided having a first end and a second end. The first end is secured in the insulated portion of the body. The second end is secured in the conductive portion of the body, thereby shorting and grounding the conductive loop. An RF connector is provided for coupling the first end of the conductive loop to time domain reflectometry instrumentation.

Abstract: The invention relates to a system for mixing a liquid with another liquid or a solid material by blowing a gas onto the surface of the liquid. The invention further relates to a system for implementing said method. Gas is blown onto the surface of the liquid from a distance which can be adjusted by determining the level of the liquid. A system of the invention, hence, comprises a device for blowing a gas onto the surface of a liquid and a device for detecting the level of a liquid.

Abstract: Capacitive water height gauge and method in which a pair of electrically conductive plates are positioned side-by-side to form a capacitor having a capacitance which is dependent upon the dielectric properties of materials in a region above the plates. The plates are positioned beneath the body of water so that the capacitance is dependent upon the amount of water in the region above the plates, and that capacitance is monitored to determine the height of the water above the plates.

Abstract: In one embodiment of the present invention, a method for measuring fluid level use a sensor comprising a first plate having continuous electrically conductive material and a second plate having electrically conductive material disposed in segments, the electrically conductive material of the first plate in opposition to the electrically conductive material of the second plate. The method comprises immersing the sensor in the fluid with at least one segment completely immersed in the fluid and at least one said segment completely out of the fluid. The method also includes sequentially energizing the segments. Further, the method includes detecting times of voltage transitions of a first signal at the first plate, relative to the sequential energizing of the segments, as an indication of fluid level.

Abstract: A sensor apparatus is described that detects and indicates the volume 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 endless 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 volume of cryogenic fluid filled in the container at known angles of inclination.

Abstract: A method and an arrangement for identifying liquid levels, in which method a capacitor is arranged into liquid in a container, between plates of which capacitor, liquid will enter in such a manner that the liquid-filled portion of the space between the plates changes with liquid levels and determines the capacitance of the capacitor. In the invention, a signal obtained from the capacitor is employed, the signal being dependent on the liquid level in the container. A coil is connected to the capacitor forming an electrical circuit with the capacitor, whereby the liquid level, while determining the capacitance of the capacitor, at the same time determines the resonance frequency of the electrical circuit. The resonance frequency is measured from outside the container inductively without a lead-through to the container.

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: Time Domain Reflectometry ("TDR") methods and apparatus for measuring propagation velocities of RF pulses to determine material liquid contents, moisture profiles, material levels and dielectric constants including: i) TDR probes and/or probe adaptors, including series averaging probes and multi-segment probes, all employing remotely operable, normally open, variable impedance devices such as diodes; ii) bias insertion and switching networks for rendering selected normally open variable impedance devices conductive one at a time to establish precise unambiguous timing markers T.sub.1 . . . T.sub.

Abstract: A liquid level sensor based on a closed field circuit comprises a ring oscillator using a symmetrical array of plate units that creates a displacement current. The displacement current varies as a function of the proximity of a liquid to the plate units. The ring oscillator circuit produces an output signal with a frequency inversely proportional to the presence of a liquid. A continuous liquid level sensing device and a two point sensing device are both proposed sensing arrangements. A second set of plates may be located inside of the probe housing relative to the sensing plate units. The second set of plates prevent any interference between the sensing plate units.

Abstract: Free space within a chamber is filled with a flowable material via an opening in a surface of the chamber. A delivery force is used to deliver the flowable material into the chamber via the opening. An outwardly directed force, independent of the delivery force, is applied to draw the flowable material away from the opening. The extent to which the free space within the chamber has been filled is sensed. And the delivering of the flowable material is controlled in response to the sensing. A wall of the chamber defines a longer dimension and a shorter dimension and the opening is in a portion of the wall that defines the longer dimension. The flowable material is delivered into the chamber via the opening in a manner such that, as the flowable material fills the chamber, a surface of the flowable material moves toward the opening along the longer dimension of the chamber.

Abstract: A capacitive measuring device with a measuring electrode (3) arranged some distance from a counter-electrode (8), a dielectric material for analysis is arranged between the electrodes (3, 8), and a measuring current (IC) is supplied to the measuring electrode (3) and the capacitance-dependent capacitor voltage (UC) is measured and evaluated.

Abstract: The valve includes a valve body (10) with a closure member (12) and a fitting region (16) enabling the valve to be fixed, in a removable manner, to the neck of a gas container. The level gauge (20 ) is a capacitive gauge consisting of an elongate rod (24) and a cylindrical tube (22) coaxially surrounding the said rod (24), the tube (22) and the rod (24) both being supported by the valve body (10) and extending over the entire height of the container. The level measurement is based on the capacitance between the rod (24) and the tube (22) and is indicated by a display device.

Abstract: An insulated probe assembly is disclosed for use with a process instrument adapted to detect a condition of a material in a process vessel. The probe assembly includes an adaptor receivable in an opening of the process vessel. The adaptor includes a through opening having an enlarged counterbore at an outer end defining an inner shoulder. A probe extends through the adaptor into the process vessel. The probe narrows from an outer process end to an inner end at a sloped shoulder positioned in the counterbore of the adaptor. An insulator sleeve surrounds the probe and has an inner end extending into the adaptor counterbore and engaging the shoulder, and an opposite outer end extending beyond an outer end of the probe. A plug is provided for sealing the probe in the insulator sleeve at the sleeve outer end. A tubular insulating probe cover surrounds the sloped shoulder of the probe and is at least partially received in the adaptor end of the insulator sleeve and extends beyond the shoulder.

Abstract: A connector for a fuel gauge in a fuel cell which has an inner tube (12) and a spaced-apart concentric outer tube (14). A housing assembly (16) is mountable to outer tube (14) and includes a contact (19) electrically connected to the outer tube. A sleeve assembly (25) is slidably mounted in a bore (24) in the housing assembly and extends through an opening (29) through the outer tube, and a first end (32) of a contact assembly (26) within sleeve assembly (25) extends through an opening (35) in the inner tube and self-secures thereto. The contact assembly of the sleeve assembly makes electrical contact with the inner tube (12) at opening (35) and is connected at second end (33) by an electrical lead to the fuel gauge. An electrical lead also connects contact (19) connected to outer tube (14), to the fuel gauge so that an electrical potential between the inner tube and the outer tube may be measured.

Abstract: A capacitor is created in an ink tank supplying ink to an ink jet printhead by placing parallel capacitive plates on sides of the tank with the ink therebetween acting as the capacitor dielectric. An electrical AC potential is applied across the capacitor. Changes in current flow through the plates are detected in a phase sensitive bridge circuit and digital signals are generated and sent to a processor for conversion into low ink level signals. The output signal is also used to identify a particular type of ink by either comparing points on a characteristic curve of the ink volume verses capacitance or, in a second embodiment, by periodically sweeping an applied oscillator voltage over a selected frequency range and comparing measured electrical resonance parameters for the ink tank capacitor with stored information about resonance parameters for different types of ink.

Abstract: In the presence of a defect in the insulation cover of known probes, liquid medium can leak from the container into the interior space of the housing of the probe, and from there into the surrounding environment, and endanger or even injure persons present there. The probe housing has an interior space with two chambers. The first chamber, which is close to the container, is capable of withstanding the pressure prevailing in the container. A passage opening present between the first chamber and the second chamber for the sensor electrode, or for its electrical conductor, is closed by a movable closing part or a stationary closing element. In the event of leakage through the insulation cover, the pressure would be transmitted from the container into the first chamber, but could not propagate from there into the second chamber and on from there.

Abstract: A capacitive fluid level sensing pipette probe adapted to be used in an automated random access immunoassay analyzer is provided. The pipette probe comprises an elongated shaft having a conductive tip. An integrated circuit chip containing capacitive sensing circuitry is positioned on the pipette probe itself, or in very close proximity. With this arrangement, the sensing circuitry moves with the pipette probe as it is raised and lowered into and out of a vessel containing a liquid. Thus, errors associated with capacitance caused by flexing connector cables is eliminated. Flex tape wiring may be used to carry data from the capacitive sensing circuitry on the pipette probe to the processing board of the automated immunoassay analyzer.

Abstract: A sensor system is operable for detecting the presence of water in an oil emulsion inside the lower gear unit of a marine engine, and for providing an alarm signal when the presence of water is detected within the gear unit. The sensor system includes a ring oscillator circuit and a symmetrical array of passive input probes which are disposed in the oil/water emulsion inside the oil chamber. Each of the passive input probes is electrically connected to the ring oscillator circuit wherein the probes function as fixed capacitors for measuring the electrical characteristics of the emulsion. When a voltage is applied to the oscillator circuit, the oscillator circuit generates an oscillating signal that circulates at a frequency which varies according to the dielectric-properties of the liquid emulsion. When water is introduced into the chamber, the water is emulsified with the oil thereby changing the electrical characteristics of the oil.

Abstract: A liquid supply module includes one or more sets of bulk liquid containers each supplying a respective reservoir via a liquid supply line. The bulk liquid containers and reservoirs are vented above the highest liquid level in the system. A pump periodically removes a known volume of liquid from a reservoir which is replenished from a bulk liquid container. A sensor detects a liquid/air transition in the liquid supply line to the reservoir indicative of the exhaustion of liquid resupply from the bulk liquid container. Art air vent solenoid valve in communication with the reservoir is closed when an empty bulk liquid container is replaced. Normal pump operation siphons liquid out of the bulk container after container replacement. A control system tracks pump iterations and calculates a number of executable iterations remaining before the reservoir runs dry.

Abstract: A solenoid valve for a water purification system. The solenoid valve contains a fluid valve which can move between an opened position and a closed position, and a coil which moves the valve to the open position when a first voltage is supplied to the coil and maintains the valve in the open position as a second voltage is supplied to the coil. The coil is coupled to a control circuit which initially supplies the first voltage to the coil when the valve is to be opened, and then reduces the first voltage to the second voltage after the valve is in the open position.