Abstract: The invention provides a level sensing device for sensing the level of an electrically conductive liquid in a vessel or container, the level being determined both by visual observation of the level of the liguid in a sight glass which is in communication with the interior of the vessel, and by detecting the level of the liquid in the sight glass by the use of an electrically conductive layer on at least one of the interior and exterior surfaces of the sight glass. The device provides a warning alarm when the level of the liquid drops below or exceeds a predetermined low or high level in the vessel.

Abstract: A method for measuring liquid content of a porous medium such as soil applies a voltage to a plurality of point contacts placed in the porous medium to be measured for liquid content, as well as to a common electrode also inserted into the porous medium to be measured in spaced relation to the point contacts. Liquid content in the soil is determined as a function of the number of the point contacts having electrical continuity with the common electrode through the porous medium to be measured for liquid content. A predetermined electrical resistance is inserted between each of the point contacts and a source of the voltage applied to the point contacts.

Abstract: In a fluid level measurement system for the measurement of a level of fluid in a vessel the electrical impedance of a first conduction path between a central rod electrode and a surrounding cylindrical electrode and the electrical impedance of the second conduction path between the cylinder and the vessel are established. The first conduction path is restricted to be below the minimum fluid level by an insulating coating on the rod. The second conduction path varies with the fluid level. An output signal is extracted from the electrodes potentiometrically which is indicative of the fluid level. The signal may be linearized by application to a circuit having a matched non-linear transfer function. With this arrangement, a continuous output signal indicative of the fluid level is produced which is not subject to errors due to changes in fluid resistivity.

Abstract: A sensor apparatus for sensing an out-of-syrup condition in association with a machine for dispensing a beverage and in which the beverage is constituted of a syrup concentrate and water. The sensor comprises a housing having a through passage and a transverse hole which receives a cap for supporting a probe that extends partially into the through passage. The probe is preferably disposed vertically and operates on a gravity principle so that when the syrup is depleted, a gap forms and the syrup liquid essentially breaks away from the probe causing a high resistance indication that is detected.

Abstract: Diesel fuel tends to deposit an insulating coating on surfaces it contacts. A probe, preferably in the form of a siphon tube, is coupled to a detection circuit which is responsive to either low resistance or high capacitance between the probe and ground. The probe is initially uncoated to make a resistive coupling to a fuel container when accumulated water touches the probe. When insulating deposits from the diesel fuel or other fuel oil coat the probe, capacitive coupling will occur between the probe and the accumulated water. In either case the presence of water triggers an output signal by the detection circuit.

Abstract: This invention pertains to gauge apparatus for measuring liquid levels comprising an elongated electrical sensor adapted to be arranged in upright position while immersed so constructed as to have an electrical resistance which may be varied. A spherical float is magnetically attracted to the sensor for rolling movement with respect thereto for varying the resistance in response to variation in elevation of float caused by changes in the level of the liquid. The resistance is measured thereby to provide an indication of such level. The magnetic attraction holds the float and sensor in operative engagement at all times including those during which the float changes height in response to changes in the level of the liquid being measured. The presence of different liquid is also detected in a given vessel, such as gasoline and water, and an indication and alarm of vessel overfill during a filling operation is provided.

Abstract: A probeless fluid level detector and controller is disclosed for use in monitoring and controlling the level of a conductive fluid within a container. The detector includes a multiple pin terminal strip intrusively mounted into the container. The strip is sealed to the container by a mixture of epoxy and container filings. The strip is electrically connected to a controller which controls the level of the container.

Abstract: An electrically conductive liquid level sensor utilizing a pair of parallel closely spaced electrically conducting probes that are exposed within a liquid container for immersion in said liquid. The sensor includes an electrical insulator partition extending between the probes so as to interrupt any direct path therebetween while at the same time localizing the conduction path to a narrow band of liquid levels due to the close spacing of the probes.

Abstract: An electromagnetically actuatable probe is inserted in a vessel containing a body of liquid and in which high pressure, high temperature, corrosive, or other hostile conditions exist. Pulses are transmitted to the probe within a predetermined range of frequencies which include the normal resonant frequency of the probe. Return signals are generated by the probe between the times the transmitted pulses are sent. These return pulses are processed to produce signals which are a function of the level of the liquid that are then employed to control the discharge of the liquid or used by another utilization circuit.

Abstract: A detector system for sensing the presence, or absence, of electrically-conductive liquid in contact with two probe members. The system includes switchable voltage sources to selectively establish a potential across capacitors connected to the probe members, and detection systems for sensing the magnitudes of charges on the capacitors. The magnitudes of the sampled charge at given intervals is indicative of the presence, or absence, of ionic liquid in contact with the probe members.

Abstract: An ink level detector for use with an ink jet printer includes two electrodes for sensing changes in ink level inside an ink reservoir due to consumption. Fresh ink is supplied to the reservoir from an ink cartridge which is mounted in an upper wall of the reservoir. At least one of the two electrodes is positioned adjacent to a location where the cartridge is mounted to the upper wall of the reservoir.

Abstract: A container (1) formed of two half shells has wall ribs (3, 4) extending parallel to each other from one side down to the lowest point in the container. A conductive foil (5) is fastened by rivets to said wall ribs. The conductive foil serves for measuring the level in the container. It is wetted on both sides by the liquid in the container. As a result, the resistance of the conductive foil (5) changes, as can be determined in an evaluation device. It is important that the conductive foil be held by holding means of the container wall (2) so that it can positively reach the lowermost point of the container and participate in deformations of the container.

Abstract: In a circuit arrangement for the electrothermal measurement of level with a resistance sensor (1) which can be fed by a source of constant current (3), a flow-of-operation control (12) for timed operation of the circuit arrangement in scanning periods is provided. By the flow-of-operation control the resistance sensor is heated periodically, namely only during a heating time (t.sub.0 to t.sub.1) at the start of a scanning period. By the flow-of-operation control the compensation voltage is, in this connection, detected by the resistance sensor and provisionally stored. At the end of the heating time another detection is effected, this time of the measurement voltage. By dividing the measurement voltage by the compensation voltage a value which is analogous to the level of a fluid surrounding the resistance sensor is formed. This value contains practically no disturbing variables.

Abstract: The impedance of a zone above bulk material in a bin is measured as a probe is reciprocated toward and away from the material in this zone. The direction-change location of the probe which corresponds to the measured impedance reaching a set point value, is detected and utilized to provide the control signal for automatically replenishing the material in the bin.

Abstract: Apparatus for monitoring and controlling the level of fluid in a reservoir. The apparatus utilizes a fluid sensing probe to monitor the level of fluid in a reservoir and can generally be installed in an existing fluid reservoir without requiring structural modification of the reservoir. The apparatus, in determining the level of fluid in a reservoir, compensates for swells and other surface undulations which mask the true fluid level in the reservoir.

Abstract: An ink jet recorder comprises a first tank as an ink supply source, a second tank as an ink supply source for the first tank, and three switching means and a pump arranged in an ink supply path. By controlling open/close states of the switching means and operation condition of the pump, print mode, supply mode, pressure mode, circulation mode or store mode can be selectively established.

Abstract: A moisture intrusion detection system is provided, wherein a plurality of independent and insular moisture detecting units are placed in a predetermined spaced apart relationship across the surface of a roof structure, or other system incorporating a water impermeable membrane, beneath the water impermeable membrane thereof. Each of the detecting units includes a moisture detecting and power supply unit and signalling unit. When moisture penetrates the water impermeable membrane of the roof structure, a leak condition exists and a water activated battery is activated. Each detecting unit in contact with water is activated. In combination with the detecting units, position and direction locator apparatus are used in combination with the detecting units to localize the source of the leak and the extent of any water damage caused thereby.

Abstract: A system for actuating a warning device when the level of a liquid in a receptacle is below a preselected level. This system includes a probe formed from a length of positive temperature coefficient wire whereby the resistance through the wire increases with increased temperature. This wire is mounted within the receptacle in a manner that allows the wire to be submerged in the liquid under normal conditions. A detection can be made when such wire is partially or completely out of the liquid. There is a first switching means in the system to apply a voltage across the wire and a detector means for actuating the warning device in response to an electrical characteristic of the wire as determined at a preselected control point in the circuit including the probe. In accordance with the preferred embodiment, the detector means includes a capacitor and a second switching means to ground the capacitor for a preselected time and then use the charged capacitor to follow the voltage of the probe.

Abstract: Disclosed is a monitoring system and method for detecting the presence or absence of material at a location. The apparatus may generally be constructed to include a sensing unit, including an antenna probe for positioning at the location wherein material is to be detected, and a control unit for responding to signals from the sensing unit indicating the presence of material at the antenna probe. The control unit may include an indicator to inform an operator of the presence or absence of material at the antenna probe, and also an output which enables peripheral equipment to operate only under selected conditions at the antenna probe. The sensing signal from the sensing unit is dc, with fluctuations indicating the presence of material at the antenna probe.

Abstract: The output of a capacitance fuel sensor is supplied to two switches that are controlled by a switching control unit. The two switches are opened and closed in synchronism and antiphase with one another, and in quadrature with the drive voltage applied to the sensor. The output of one switch is supplied to the input of a first integrating current-to-voltage amplifier which in turn supplies a signal representative of fuel quantity to a fuel indicator. The output of the other switch is supplied to another integrating current-to-voltage amplifier which in turn supplies a signal representative of the quantity of contaminants to a contaminant indicator.

Abstract: A liquid leak detecting sensor in cable form is provided wherein an element of the cable is a material which is easily deformable and which, on deformation, maintains the cable in the deformed configuration.

Abstract: A thermoelectric level detector employs an impedance element, at least a portion of which is meandering in configuration in which the resistive path repeatedly traverses the axis thereof, to detect the level of liquid in a tank. The impedance of the element depends on temperature and provides a measure of the liquid level. The pitch of the meander is relatively small in the reserve region of the tank to provide fine resolution in this region.

Abstract: In a device for the electric measurement of the level of a liquid in a container, particularly in the gasoline tank of a vehicle, a support developed as protective tube of a conductor foil is fastened for swinging against the force of a spring (14 and 21) to the top of the container. In order to be able to arrange the support even in containers in which the point of attachment of the support is lower than the highest level to be detected, the support is subdivided into three approximately rigid sections, (2, 3, 5) each two sections (3, 5) being articulated in the manner of a toggle joint to each other and being under spring action. In this way the outermost section (3) is swung, substantially independently of the inside height of the container, on the one end towards the bottom (4) and on the other end towards the top (1) of the container.

Abstract: An energy transfer network is used to ensure reliable operation of a low water sensing system for a boiler. The energy transfer network provides a sufficient time interval to make sure that wave action and boiling within the boiler do not simulate the loss of water. The energy transfer network is structured to be discharged in the event water actually drops below an appropriate level. The energy transfer network provides for the continuous presence of water so that boiling action does not simulate an artificially high (presence of) water level.

Abstract: The invention relates to (1) an arrangement and (2) method for the measurement of the level of an electrically conductive liquid. In a preferred form of the invention the liquid is milk provided within a suitable container. The arrangement includes at least two spaced apart electrodes and an elongate coil which are at least partially immersed in the electrically conductive liquid. Means are provided for passing an alternating current through and between the first and second electrodes, by way of the electrically conductive liquid. This forms or creates an electro-magnetic field about the first electrode which is then picked up by and current induced in the coil. Means are provided to convert and read the electro-magnetic field into a substantially linear function (current) of the level of the electrically conductive liquid. The method includes at least partially immersing at least two electrodes and one elongate coil in an electrically conductive liquid.

Abstract: An ink cartridge 10 includes an ink level sensor 38 having a probe supporting structure, such as platform 174, which projects into a collapsible ink container 16 from an ink container support 18. First and second electrical probes 40, 41 are embedded within the structure, with tip portions 188, 190 of the probes 40, 41 being exposed to provide an electrically conductive path through the ink between the probes. Flat closure surface 176, 178 are provided between the exposed portions of the probes against which the container 16 collapses. When the ink container 16 collapses against these surfaces 176, 178, the resistance between the probes increases, is insensitive to ink conductivity, and indicates that volume of ink within the cartridge is low. The platform 174 is supported by tapered necks 180, 182 projecting into the ink container from the ink container support 18.

Abstract: A device to control a temperature variable-resistive type oil fluid level sensor in vehicles. The device employs constant current excitation under control of a relay to maximize the sensor's response and employs a shut-off feature to protect the sensor from overheating.

Abstract: An in-ground control system to override an automatic sprinkling system during periods of excess rain or moisture, having a housing with a peripheral water collection trough connected to a collection chamber. Sensors are positioned in the chamber and upon a predetermined rise in the water level in the chamber will either operate a control to suspend operation of the watering system or to operate a pump to carry away excess water.

Abstract: A digital sample and hold circuit for memorizing the initial voltage across an electrical resistance probe which is partly immersed in the liquid in a tank.

Abstract: An acoustic system is provided for measuring the fluid level in oil, gas or water wells under pressure conditions that does not require an electrical link to the surface for level detection. A battery powered sound transmitter is integrated with a liquid sensor in the form of a conductivity probe, enclosed in a sealed housing which is lowered into a well by means of a wire line reel assembly. The sound transmitter generates an intense identifiable acoustic emission when the sensor contacts liquid in the well. The acoustic emissions propagate up the well which functions as a waveguide and are detected by an acoustic transducer. The output signal from the transducer is filtered to provide noise rejection outside of the acoustic signal spectrum. The filtered signal is used to indicate to an operator the liquid level in the well has been reached and the depth is read from a footage counter coupled with the wire line reel assembly at the instant the sound signal is received.

Abstract: A frequency transmission system comprises a pulse train generator and a signal converter. The pulse train generator generates a pulse signal of a sufficiently short duration in response to oscillation frequency signals, and the signal converter circuit converts the pulse signal into a current signal and blunts the waveform of the converted signal by a capacitor to transmit through power supply lines.

Abstract: A display apparatus which will numerically indicate the quantity of fluids removed from any tank or tanks by accepting the output from a unit inserted in each tank which varies in resistance from minimum to maximum as the tank moves from a full to an empty condition respectively. The apparatus applies a constant current to the variable resistance and develops a current which changes from minimum to maximum as the tank is emptied. An amplifier accepts the variable current along with a comparison current and converts the differential current to an output current. The current is subsequently applied to an adjusting companion fixed voltage. The display reads the different voltage, and displays the difference, which represents the level or final quantity remaining in the tank. The circuit can also indicate the level of each of several tanks with adjustment in the calibration of the system for each tank.

Abstract: A high pressure electrical conductivity probe generally used as a liquid level indicator having a high pressure mechanical seal between an insulator and a metal mounting body and an electrode connector. The high pressure mechanical seal is effected using a cylindrical insulator with planar end faces which are located in and sheathed in cylindrical recesses in the metal mounting body and the electrode connector. Preferred sealing means include flexible expanded graphite gaskets or a mechanical interference fit.

Abstract: An amount of a reagent remaining in a reagent bottle is detected by measuring a distance along which a delivery nozzle is moved downward from a reference level until the tip of nozzle is immersed into the reagent. The distance is measured by counting clock pulses supplied from an oscillating unit which produces the clock pulses during a time interval from the initial downward movement of the nozzle to an instant when the nozzle tip is immersed into the liquid. A count value is compared with a predetermined maximum count value by a comparing unit to derive a difference therebetween. The difference thus derived indicates a residual amount of the liquid. The number of times by which the liquid may be delivered is obtained by dividing the detected residual amount by a unit amount which is delivered by a single delivery operation.

Abstract: A precision liquid level sensor utilizes a balanced R. F. bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge.

Abstract: An apparatus and method for measuring the height of a liquid above a reference level in which short pulses of subnanosecond duration are coupled to a dual-mode transmission line immersed in a liquid to propagate thereon in a plurality of modes. A surface wave propagating on the outer conductor is reflected from the surface of the liquid, and coaxial-mode propagating within the transmission line is reflected from the reference level. These reflected pulses propagate back along the transmission line, coupled to a receiver for detection, the detected pulses processed to determine the liquid height above a reference level.

Abstract: A vertical ice cube mold chilled by a refrigeration system has a water stream pumped into its open vertical face to build up ice cubes in the mold. A probe hangs over the open mold face at an adjustable spacing. When the mold fills with ice and the water stream contacts the probe, an electrical circuit is completed to cause a control to stop the water pump and heat the mold, thus harvesting the ice cubes. A timer restarts the icemaking cycle in case ice is not delivered for some reason. Casual water contact with the probe is prevented from tripping the control through the use of a simple integrator device.

Abstract: A radiator cap having an outer shell and a pressure vacuum valve assembly for closing the filler neck of a radiator includes a probe for detecting the coolant level in the radiator. The probe projects from the cap into the radiator interior and is electrically isolated from the radiator. An electrical connection is provided through the shell to connect the probe to a power source and indicator.

Abstract: A probe and sump drain assembly (128) includes a fitting (136) secured to the wall of a sump (98) to which a probe housing 146 is threadedly engaged. The fitting is provided with a stepped bore having larger (142) and smaller (140) diameter portions. Seals (154, 156) carried on the housing (146) control fluid communication through passages (160, 162) communicated with the larger portion (142). A ring terminal assembly (170) provides an electrical connection with the fitting (136) and with a transversely projecting portion (166) of the probe (144) regardless of the angular orientation of the portion (166) of the probe (144).

Abstract: In a device for electrically monitoring the level of a liquid present in a container, a plurality of temperature-dependent resistance probes (n-1, n, n+1) are arranged at different heights in the container, they being adapted to be connected one after the other to a source of constant current (5) under the control of a program control device. For the evaluation of the voltage at one resistance probe (for example n+1) connected at the time to the source of constant current (5), a differentiator (6) is provided as well as a comparator (7), which is arranged behind the former and is and acted on by a threshold voltage and is connected to circuitry for forming a display signal. The circuitry comprises counter (4, 19) which counts the number of resistance probes (n-1, n, n+1) whose voltage differential is above the threshold voltage after connection to the source of constant current (5).

Abstract: A low liquid level sensor in a hot water heating system permitting testing operability thereof in situ without draining down the system. The sensor is located in a cavity that has an opening in the bottom thereof in fluid communication with the liquid in the vessel during normal operation of the system. The end of the opening is at a lower elevation than the sensor and liquid from the vessel is in the cavity during normal operation of the system. When the liquid drops to a predetermined low level the sensor activates the safety cut-off. Valved passed means are provided exteriorly of the vessel so that a gas can be injected into the cavity to pressurize the same and drive the liquid in the cavity through the opening into the vessel simulating a low water level condition. At the simulated low water level condition operability of the sensor can be determined. Means are provided to release the gas from the cavity.

Abstract: The invention provides an installation for testing a well by pumping by means of a submerged pump and a process for use thereof. The assembly 6 formed of an hydraulic pump and motor is carried by one end of a reinforced flexible tube 1 wound through a pulley 7 on a drum 3 actuated by the surface motor 8. . In the sheath of tube 1 are housed electric conductors 2 for supplying the motor of assembly 6. Sensors detecting the level of fluid in the well allow the submergence depth of the pump to be detected, the signals coming from this detection being able to be used to control motor 8 at the submergence depth ensuring a given flow rate. The invention applies to determination of the flow rate, pressure and temperature characteristics of a well.

Abstract: A liquid gaging system comprising a plurality of sensors, each sensor providing a liquid measurement signal relating to a liquid depth at a particular location in a tank. The invention also comprises apparatus for selectively monitoring individual sensors one at a time. The apparatus for selectively monitoring is connected to the sensors.

Abstract: A novel and improved system is provided for detecting the apical constriction in the root canal of a tooth, in which the root canal, from which the dental pulp has been removed, is filled with electrolyte solution, a first electrode is put in contact with the mucous membrane in the oral cavity, a second electrode is put in the root canal, a fixed voltage or current is applied between the first and second electrodes, and a third electrode having an insulating coating except for the tip thereof is inserted into the root canal to detect sudden change in the potential along the root canal, and this change is visually and/or audibly indicated to indicate the apical constriction.

Abstract: An electronic liquid level gauge for measuring the level of a liquid contained in a vessel by employing an electrode pair immersed in the liquid. The electrode pair is associated with an oscillator which generates pulses of a repetition period directly proportional to the electrostatic capacity of the electrode pair. A counter is provided which is reset by an oscillator pulse and starts counting reference pulses of a predetermined repetition rate with a predetermined time delay relative to the occurrence of the oscillator pulse.

Abstract: A device for the electric monitoring of the level of a liquid contained in a container, comprising at least one temperaturedependent resistance sensor immersed in the liquid the level of which is to be monitored, a constant current source being connectable to the resistance sensor under the control of a program control device controlling a device for detecting and storing the initial voltage drop on the resistance sensor at an initial time and the measurement voltage at a specified time after connection of the constant current source, and a device for evaluating the voltages by subtracting the measurement voltage from the initial voltage and under the circumstances inverting the difference to form a display voltage which corresponds to the level of the liquid.

Abstract: A method and apparatus for measuring the thickness of an ice sheet floating on a body of sea water is disclosed. The electrical inductance of a coil embedded in an ice sheet is measured. This inductance is solely dependent on the geometrical factors of the coil and is minimally affected by variations in salinity of the sea water on which the ice sheet is floating. The measured inductance is the actual inductance only of the part of the coil in the ice. The other part of the coil, protruding in the sea water, is shorted out by the sea water. Hence, the thickness of the ice sheet is directly related to the measured inductance.

Abstract: A pneumatic valve system for sealing off the flow of a liquid at the intersection of two pipes, one of the pipes being vertically disposed with respect to the other pipe. A sensing probe senses liquid at a pre-established height in the vertically disposed height which signals a control system to activate the pneumatic valve system. An expandable, inflatable bladder is positioned from the vertically disposed pipe into the second pipe and is inflated, thereby sealing off the flow of liquid past the bladder. When normal fluid flow is to return, the bladder is deflated and positioned back into its original position within the vertically disposed pipe.

Abstract: A two electrode probe is lowered into a vessel and the electrodes are electrically interconnected by liquid steel; the resistance condition then existing is ascertained as reference value against which subsequent resistance measurements are referenced as the probe is lifted from the vessel. The traversal of the slag-liquid metal interface causes a relative resistance change permitting selection of a threshold level that is independent from other measuring and operating parameters. The threshold device operates a counter in that for example forward and reverse counting tracks the lowering and lifting of the probe, but counting is halted when the interface level is reached, the count state then indicating the spacing of a zero level of the probe position from the level in which the threshold was exceeded in a particular direction.

Abstract: A wire wound resistor is vertically disposed in a vessel. The resistor has a former of between 20 mm and 45 mm diameter and resistance wire of a resistance of between 1 and 4 ohms per turn connected in the circuit of an A.C. bridge-circuit. Impedance change is indicated on a display unit calibrated to indicate the change in level of liquid e.g. milk in the vessel. The resistance wire is laid on the former by applying ultrasonic sound energy to soften the former which is of polysulfone or polycarbonate and the wire embedded in the softened former material. The vessel is shaped at the lower end to assist in giving linear readings when the level of liquid is low.