Abstract: An apparatus for establishing and/or monitoring a predetermined filling level in a container is described, which apparatus can be used in a wide range of applications, that is to say in many different media, which apparatus comprises: a housing (1), an oscillating element for projecting into the container, a diaphragm (5), which is fixedly clamped into the housing (1) at its edge and to which the oscillating element is fastened, and an electromechanical transducer for exciting the diaphragm (5) to produce oscillations in dependence on a transmission signal (S) present at the transducer and for receiving and converting oscillations thereof into an electrical reception signal (E), in which a percentage interval between a resonant frequency fr and an antiresonant frequency far divided by the resonant frequency fr exceeds 20% when the oscillating element oscillates in air.

Abstract: An electrically resistive fluid level sensor and system for sensing fluid levels in a container, for example washing machine basins, and for closing a supply of fluid to the container when the fluid level in the container reaches a specified level. The system includes generally fluid level resistive element portions disposed in the container and electrically connectable by fluid therein, and an input signal source, electrically coupled to the fluid level resistive element portions, whereby an output signal across the fluid level resistive element portions is proportional to the fluid level. Temperature resistive element portions are preferably disposed in the container and connected in series between the input signal source and the fluid level resistive element portions to substantially cancel any thermal effects on fluid level sensing and control.

Abstract: The invention is an oil-water detection device for monitoring the presence of water in a container. The device consists of a probe having two thin strips of sheeting within a fiberglass circuit board for sensing the presence of water in a container and generating a signal dependent on the presence of water, a divide counter and Stamp II micro-processor and an accessory communications link connected to the micro-processor. A power supply is also provided. The detection device can differentiate between oil and water and will not be activated merely by the presence of oil on the water.

Abstract: A two stage alarm system for detecting rising levels of sludge in septic tanks, and similar sedimentary tanks. The system, to detect a first or “caution” level, and a second or “critical” level of sludge, relies upon a pair of vertically positioned weight sensitive switching mechanisms which, when triggered by the rising levels of sludge, will send appropriate signals to a remote alarm mechanism, such as at the residence, to activate a “yellow” and/or “red” light, for example, thus alerting the owner of the tank to the need for remedial action.

Abstract: A float sensor that is modular has a mounting bracket which incorporates an O-ring seal and bayonet style resilient mounting fingers which lock the mounting bracket to a tank flange. A tube is ultrasonically welded to the mounting bracket and positions a reed switch housing which is ultrasonically welded to the end of the tube opposite the mounting bracket. The reed switch housing incorporates a stop positioned above a descending cone. The cone terminates in radially outwardly extending fingers that lock a float to the reed switch housing. The float is free to float upwardly along the cone to engage the stop. The float has a ring shaped magnet foamed in place within a low density plastic body. The presence of fluid buoys the float upwardly until the float engages the stop.

Abstract: A liquid supplying device comprising a liquid container for storing a liquid so as to supply an external device and a liquid level sensor for detecting the liquid level. As the liquid within the liquid container is gradually used up, liquid level drops. As soon as the remaining liquid in the container drops to a predetermined amount, the liquid level sensor emits a warning signal to the operator, and the operator can then replenish the liquid in the container.

Abstract: A system for visually indicating activation of an alarm, even if the alarm is no longer activated. The system has a moveable visual indicator having an elongated shaft with a stop at one end, the shaft extending through a guide mounted on the alarm. A magnet on the stop temporarily affixes the visual indicator to the alarm until the alarm is activated, at which time the visual indicator separates from the alarm and falls vertically to protrude from the guide, indicating that the alarm has been activated.

Abstract: A new leak collection and supply shut off system for closing off the supply of water and energy to a water heater in the event of a leak. The inventive device is designed for use with a water heater that has a tank, a water inlet pipe, a water outlet pipe, and an energy supply line. The leak collection and supply shut off system comprises a container that is adapted for positioning under a water heater and holding water. The container has a base, a sidewall, and an open top. A water valve closes the water inlet pipe of the water heater when the level of water in the container is equal to or greater than a predetermined level. An energy shut off device closes the energy supply line of the water heater when the level of water in the container is equal to or greater than the predetermined level.

Abstract: A method and apparatus for processing a time domain reflectometry (TDR) signal having a plurality of reflection pulses to generate a valid output result corresponding to a process variable for a material in a vessel. The method includes the steps of determining an initial reference signal along a probe, storing the initial reference signal as an active reference signal, periodically detecting a TDR signal along the probe in the vessel, and computing the output result using the TDR signal and the active reference signal. The method also includes the steps of determining an appropriate time for updating the active reference signal, automatically computing an updated reference signal at the appropriate time, and overwriting the active reference signal with the updated reference signal for use in subsequent computations of the output result.

Abstract: An alarm mechanism for use in chlorinators using chlorine tablets. The alarm mechanism signals when the chlorine tablets have dissolved to a pre-determined quantity and are in need of replenishment. The alarm mechanism has a low tablet register mechanism and an indicator. The low tablet register mechanism registers when the chlorine tablets dissolve to the pre-determined quantity, and preferably includes a counterweight mechanism calibrated and constructed so that it is activated when the chlorine tablets dissolve to the pre-determined quantity. The indicator indicates when the low tablet register mechanism registers that the chlorine tablets have dissolved to the pre-determined quantity. Preferably, the indicator includes a sensor and an alarm. The sensor senses when the register mechanism registers the dissolution of the chlorine tablets to the pre-determined quantity. The alarm, such as a horn or a light, signals the activation of the sensor.

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

Abstract: An apparatus and method for optical sensing of liquid level in cooking vessels are disclosed. The apparatus comprises: a first sensor (P1) for detecting a liquid and generating a first signal indicating a vessel level of the detected liquid above a desired liquid level (110) in the cooking vessel (102); a second sensor (P2) for detecting the liquid and generating a second signal indicating the vessel level of the detected liquid below the desired liquid level (110) in the cooking vessel (102); a third sensor (P3) for detecting the liquid and generating a third signal indicating the vessel level of the detected liquid (110) at the bottom of the cooking vessel (102); and a controller (108) for receiving the signals and for determining the vessel level in the cooking vessel (102).

Abstract: An apparatus and method for monitoring parameters of combustible liquids within a tank includes a plurality of sensors disposable within the tank for generating signals indicative of parameters of the contents of the tank, a display disposed on the outside of the tank for generating human perceptible signals indicating parameters regarding the contents of the tank, and a nonconductive communications mechanism for conveying signals between the sensors and the display. The sensor generates electrical signals indicative of the parameter(s) measured. The electrical signal is then converted into an optical signal such as pulses of light. The optical signal is conveyed along the electrically nonconductive communications mechanism to the display. The optical signal is then converted back into an electrical signal outside of the tank where it may be processed to produce a human perceptible signal indicative of the parameter(s) measured.

Abstract: An electronic pump switching system comprises a water sensor coupled to a comparator which generates an output signal when water is sensed. The comparator output is coupled to a timer, which is initiated for a predetermined period by the comparator output signal. The timer is coupled to a switch which activates a coupled device, such as a pump, for the predetermined period. The continued presence of water at the sensor at the end of a predetermined period causes the timer to time a new predetermined period, whereby the coupled device remains activated. The sensor may be formed from a pair of electrodes arrayed as a voltage divider. The voltage divider action may additionally serve as a discriminator, allowing timer operation to be tied to the detection of water, as opposed to petroleum products, such as fuel.

Abstract: In order to control the delivery of a liquid to a vessel, a liquid level control system includes a regulated supply of low pressure air delivered to an air supply tube which extends to a liquid vessel for discharging the low pressure air at a preselected level within the liquid vessel. The control system also includes a sensor sensing fluctuations in air pressure at an intermediate point along the air supply tube. In particular, the sensor senses a first air pressure when the liquid is below the preselected level and sensing a second, higher air pressure when the liquid is at or above the preselected level. The sensor is in communication with the liquid supply source to produce a signal upon sensing the second, higher air pressure in the air supply tube. When the higher pressure is sensed, the sensor sends the signal it produced and the liquid supply source is responsive to the signal to stop supplying liquid to the liquid vessel.

Abstract: An automated gas cylinder monitoring system includes: a data storage collar associated with a gas cylinder including a resident memory and an insulated housing, the insulated housing being configured for coupling with a gas cylinder; a read/write probe for writing data to and receiving data from the resident memory of said data storage collar; measuring devices for determining the volume of gas in a gas cylinder; and a host computer for transmitting information to and receiving information from the read/write probe.

Abstract: The electronic interface circuit can perform ratiometric processing and driving of a signal generated by a fuel-level detector of a vehicle. The circuit uses a current mirror configured so as to send one half of the output current to the input resistance and one half of the output current to earth. The current mirror is controlled by a voltage taken from the input resistance and by a voltage taken from a resistive divider, the latter voltage having been filtered by a low-pass filter, so as to achieve ratiometric processing of the input signal.

Abstract: The invention includes a system for monitoring the performance of an automatic dosing siphon utilized in reservoir which is a part of a wastewater treatment system. The siphon includes a bell type cover, a fluid trap having one leg extending upward into the bell, and an outlet discharge pipe connected to said trap. A flow detect switch is located in the discharge pipe. Upon siphon activation the switch is opened and a countdown timer is reset. After draining the reservoir, the switch closes and the timer starts counting down a predetermined time period. If the siphon doesn't activate, time expires and an alarm is triggered. A second system utilizes a solenoid drain valve located above the outlet portion of the siphon trap such that upon time expiring the valve opens, the tank drains, and the timer resets. The valve automatically reprimes the siphon. The system continues to monitor the siphon and initiates an alarm upon subsequent siphon failures.

Abstract: A modular overfill alarm assembly is constructed and arranged to be installed in-line with a vent pipe in a vented storage tank for liquids such as waste oil or gasoline. The alarm assembly includes a vent tube having an open lower end that is threaded to be mounted to a vent opening in a vented storage tank, and an open upper end that is threaded to have a vent pipe mounted thereto, so that the vent pipe may be communicated with the vent opening as it would if it were threaded directly into the opening. The assembly further includes a support bracket mounted to the vent pipe and vent tube for supporting a commercially available alarm for actuating the alarm.

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: An apparatus for establishing and/or monitoring a predetermined filling level in a container is provided, in which a reception signal (E) is equal to the measurement signal, and in which a fixed phase difference (.DELTA..phi..sub.R), which is independent of the oscillation quality of the apparatus, exists between a first transmission signal (S.sub.1), and a reception signal (E) at a resonant frequency (f.sub.r).

Abstract: A disposable fluid level sensor of the present invention determines the level of fluid in a container. A flex circuit sensor is coupled to a processing module having a power supply, the flex circuit sensor being mounted at a selectable location by an adhesive patch which holds the sensor flush against the container. The processing module hangs from the flex circuit, and provides a human perceptible indication, such as a flashing light or an audible alarm, when the fluid level drops below a desired point as determined by the sensor. The sensor detects the change in fluid level by transmitting an electromagnetic signal and determining whether there is a change in reflected energy.

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

Abstract: The electronic switching device serves to control the connection of a load to a voltage source by a switch which is controlled in a first operating mode directly by a binary signal furnished by a signal processing circuit and in a second operating mode inverted. The switching device has three terminals, of which the first permanently remains connected to a first terminal of the voltage source and to a first terminal of the load, whilst of the other two switching device terminals the one is connected to the second terminal of the voltage source and the other to the second terminal of the load. The switching device is configured so that it can be changed over from the one operating mode into the other by interchanging the connections between these two other switching device terminals and the second terminals of the voltage source and of the load, respectively.

Abstract: A toilet (6) has a solenoidal valve (1) in working relationship to a water-level probe (23), an overflow probe (25) and a floor-water probe (21) to prevent leaks reliably. A signal alarm (31) also is provided to warn of any problems and where they are in order to be able to repair them without the services of a professional plumber in many instances.

Abstract: A level measuring device using microwaves comprises an antenna for sending transmitted waves toward the surface of a material whose level is to be measured, and for the reception of echo waves resulting from reflection at the surface, and a receiving and evaluating circuit which derives from the echo waves received by the antenna an echo function representative of the echo amplitudes as a function of the distance and determines from the echo function the transit time of the microwaves from the antenna to the surface of the material and therefrom the distance of the surface of the material from the antenna.

Abstract: A dispensing system includes a robot that controls the positional location of a dispenser that dispenses a bead of material, such an adhesive, onto a substrate and wherein a sensor monitors the geometric configuration of the material dispensed. The dispensing system also includes a control circuit which receives information from the sensor so as to monitor geometric characteristics such as height, width and cross sectional area in such a manner that statistical process data can be gathered and also to provide alarm indications whenever the height or width of the bead do not comply with predetermined characteristics. The control circuit also provides a closed loop feedback system so that the supply of material and the nozzle can be controlled in such a manner to modify the flow of bead material whenever a discrepancy or error is detected by the control circuit.

Abstract: Apparatus for indicating material level that includes a pair of ultrasonic transducers on opposed sides of a space for receiving the material at the level to be detected. A swept frequency oscillator is coupled to one of the transducers so that the transducer radiates into the material space ultrasonic energy that continuously sweeps back and forth between a low frequency range at which such energy is transmitted to the other transducer by resonance of the entire apparatus and independent of presence of material in the material space, and a higher frequency range at which such energy is transmitted to the other transducer only when material is present in the space between the transducers. Detection circuitry indicates presence of material between the transducers upon receipt of the higher frequency energy, and failure of the apparatus upon failure to receive the lower frequency energy.

Abstract: A drinking container having a serving counter, comprising a vessel for receiving a substantially standard serving of fluid; a serving counter mechanism comprising a ring member which is slidably engaged with the vessel and which includes a series of numbers printed thereon; and a pointing member disposed along the outer surface of the vessel substantially proximally to the ring member and having a corner which indicates a number from the number series corresponding to the number of standard sized servings of fluid which have been consumed over the course of a 24 hour period.

Abstract: An improved paper image reproduction device being communicatively integrated into a communications network and having a cabinet having at least one cassette receiver for receiving a paper cassette and a paper cassette paired with each such paper cassette receiver, the paper cassette bearing a supply of stacked paper sheets, includes a detector disposed with the cabinet for sensing a partial supply of paper in each such paper cassette. A signal generator is coupled to the detector and is communicatively coupled to the communications network for providing a signal to the local area network representative of a partial supply of paper in each such paper cassette. The local area network communicates such signal to at least one station on the communications network.

Abstract: A liquid level sensor device, particularly adapted for use with corrosive and hazardous liquids such as oil, for measuring the liquid level in a storage tank or vessel. A tubular device is placed vertically in a liquid storage tank and senses the liquid level by having a float embedded with magnets move vertically along the axis of reed switches encased in the tubular device. The device contains temperature sensors to measure the temperature of the tank fluid, and microprocessors that scan the reed switches, transmitting data through a connector in the device top to a nearby computer for recording and transmission to a control and monitoring location. The electrical data system inside the device utilizes only two conductive trace runs throughout the device length to maximize reliability while minimizing the copper used. Special mechanical and electrical assembly connectors inside the device permit the device to flex safely in turbulent liquid conditions, without breakage.

Abstract: A liquid level detecting system which utilizes audio frequency with components having sizes and values usually associated with RF frequencies, thereby providing the reliability and low cost of audio components with the small size typically associated with RF systems. A conductive element is mounted within a container, the conductive element is provided with an insulative coating. A large change in capacitance and capacitance reactance is produced when the insulated conductive element is immersed in a conductive liquid. The change in output of the audio oscillator, passed through the low pass network, which includes the capacitance of the conductive element is fed to an active detector. In one application, the detector is utilized to sense the level of water in a fuel/water separator and, in a second application, a pair of liquid level detectors are utilized to control the operation of a bilge pump.

Abstract: To measure the level of contents in metallic tanks by means of short electromagnetic waves, it is proposed to mount the complete level measuring assembly, including the horn antenna, outside the tank. The transmitted waves are projected through an opening in the tank wall toward the surface of the medium whose level is to be measured. The opening is closed with a glass or ceramic plate. To distinguish the useful signal within the unwanted echos caused by multiple reflections of the electromagnetic waves at the glass or ceramic plate, a damping layer of a conventional damping material is interposed between the microwave coupling element and the surface of the glass or ceramic plate. To achieve an optimum signal-to-noise ratio, the damping coefficient is fixable and the distance between the level measuring assembly and the surface of the glass or ceramic plate is adjustable in the axial direction of the opening.

Abstract: A fluid level sensing system, particularly for sensing the water level in a steam generating boiler, comprises a vessel connected to the boiler so as to contain water and steam at substantially the same level as in the boiler, a number of vertically spaced electrodes projecting into the vessel, and circuitry for measuring the electrical impedance sensed by each electrode. The circuitry, which can be multiplexed to each electrode in turn, includes a first comparator for producing an output when the sensed impedance lies between the normal maximum impedance of the water and the normal minimum impedance of the steam above the water, this output being demultiplexed to drive a vertical display to show the level of the steam/water interface. The circuitry additionally includes a second comparator for producing a further output when the sensed impedance lies below the normal minimum impedance of the water, which further output is indicative of a variety of different fault conditions and drives a fault indicator.

Abstract: A leakage detection system is provided having a plurality of locally distributed integrated units with a leakage sensor, preprocessing unit, and evaluation unit which connects with the individual integrated units or with a group of integrated units via a serial bus line. In each preprocessing unit, the value measured by the leakage sensor is subjected to a temperature compensation process.

Abstract: A multiple set point material condition monitoring system is responsive both to the level of material with respect to a sensor and the extent of material coating which has accumulated on the sensor. The system provides an output when a predetermined coating thickness has been exceeded, so that the sensor may be cleaned before the coating can accumulate to the extent where a false level output is generated. The systems include three electrode guarded sensors, a bridge comparing the sensor output with a reference, and a bridge reference which is automatically and repeatedly caused to assume a sequence of values corresponding to material condition set points, one of which causes an output when a predetermined coating thickness has occurred and another of which generates a level output. In one embodiment, separate outputs are provided corresponding to each set point. In another embodiment, a single tri-state output is responsive to both set points.

Abstract: A level switch includes an operational amplifier, provided with positive and negative feedback, and a sensor, together forming an astable multivibrator. The oscillation onset and frequency of the multivibrator depend on the surface level of controlled material. The sensor includes a dielectric body on which, starting from its fastening end, a grounded opposite electrode and a screening electrode, connected to the amplifier output, are mounted. A ring plate connected to the inverting amplifier input is incorporated coaxially in the dielectric body. The level switch need not be adjusted when the controlled material is changed, although materials may have quite different electrical properties and may stick to the sensor.

Abstract: A system for monitoring the water level of a pressure drum having a pressure column comprises a plurality of electrodes communicating with the column for contacting water and steam within the column. Each electrode has its own location and produces a first output which corresponds to the presence of water or a second output which corresponds to the presence of steam. A discriminator is operatively connected to the electrodes; and the discriminator has an analog-to-digital converter for receiving the output of each electrode and converting the output to a digital signal which represents the water conductivity for each electrode. A central processor is operatively connected to the discriminator for powering the discriminator as well as for receiving the digital signals in order to determine a slope degradation between the conductivity and the location of each electrode in the column. The central processor also determines an inflection point between the water and the steam in the column.

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

Abstract: A marine craft fuel alert system is operative during a given time period, to compare actual fuel capacity measurements with selected fuel tank capacity reference values, to permit timely intervention. Used with a relatively high reference value and operative during fuel loading, the system and methodology gives a warning to a fuel input agent (i.e., person controlling fuel loading) in sufficient time for the agent to terminate fuel loading and prevent environmental pollution by fuel overfill spillage. Conversely, the system and methodology, with appropriate modifications, can be used to sense and warn of predetermined low fuel level conditions. The system can be integrally incorporated into an original equipment marine craft system or retrofit thereto. Electrical interconnections may extend to marine craft ignition system interdiction during operation of the fuel loading monitoring and warning.

Abstract: Disclosed is a method for the measurement, by means of a radar, of the distance from a useful obstacle that is surrounded by parasitic obstacles but sends back an echo which is more powerful than their echos. This method of measurement can be applied to the measuring of the level of liquid in a vessel. It consists in transmitting a sequence of non-modulated microwave signals whose discrete angular frequencies are evenly distributed in a certain frequency band, demodulating the signals received in return for the transmitted signals, subjecting the received and demodulated signals to a reverse and discrete Fourier transform with a view to a coarse localization of the delay of the echo from the useful obstacle and a high resolution method for the localization of the radiating sources with a view to a more precise localization of the delay of the echo from the useful obstacle, said delay enabling the assessment of the distance from the useful obstacle to the radar. FIG. 5.

Abstract: Disclosed is a full container recognition system (5) for determining when a container (16) having an upwardly facing opening is filled with articles (18) to a predetermined level. The system includes at least one deflectable feeler arm (10) mounted to a support (22) so that an outer end (32) of the feeler arm extends over the opening of the container. As articles (18) are loaded into the container (16), the articles impact the outer end (32) of the feeler arm (10) causing the feeler arm to deflect downwardly from an up position in which the feeler arm is biased. When the article (18) passes downwardly beyond the outer end (32) of the feeler arm (10), the biasing arrangement causes the feeler arm to return to the up position.

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

Abstract: An ice level sensor includes three capacitive plates for sensing the level of ice cubes in an ice tray or ice bucket. The ice level sensor preferably includes a relay for turning off the ice maker when a particular ice level is reached. The three capacitive plates provide immunity to frost collection because frost will collect on all plates equally. Preferably, the capacitive sensor is positioned with one plate next to the ice bucket and two plates positioned above the ice bucket. Preferably, the ice sensor may be retrofitted to existing refrigerators by mounting the capacitor plates to the rear freezer wall, and connecting AC input wires to the ice maker through a relay in the capacitor sensor.

Abstract: A fail safe output stage for a tank fluid level detection circuit having power supply/output leads periodically places a shunt across the leads to periodically generate a LOW signal which alternates with a HIGH signal to indicate an underfilled condition. In a filled condition, a steady signal appears across the leads. The output stage of the detection circuit consists of a parallel connection of switching devices where the "on" impedance of any single switching device is insufficient to place the detection circuit output lead in a LOW logic state. Therefore, in a condition where one of the switching devices fails, the detection circuit output may continue to alternate, but the alternating output is not recognized as such by a disable circuit which does not detect a LOW logic condition on the output lead. Accordingly, the failed output is interpreted as an filled condition, resulting in a shutdown of the system.

Abstract: A liquid treatment apparatus or system having a liquid treatment medium bed which is regenerated by passing through it a solution formed by dissolving a solid in a liquid. An automatic control system initiates a regeneration cycle when necessary. Indicia are provided in association with the container containing the solid material such that an appropriate indicia will represent the amount of solid material in the container. By providing the control circuit with the indicia, the control circuit will record the amount of solid material remaining and initiate an alarm when the amount of solid material remaining is below a predetermined level.

Abstract: A real time ultrasonic surface contour mapping system is provided including a digitally controlled phased-array of transmitter/receiver (T/R) elements located in a fixed position above the surface to be mapped. The surface is divided into a predetermined number of pixels which are separately scanned by an arrangement of T/R elements by applying phase delayed signals thereto that produce ultrasonic tone bursts from each T/R that arrive at a point X in phase and at the same time relative to the leading edge of the tone burst pulse so that the acoustic energies from each T/R combine in a reinforcing manner at point X. The signals produced by the reception of the echo signals reflected from point X back to the T/Rs are also delayed appropriately so that they add in phase at the input of a signal combiner. This combined signal is then processed to determine the range to the point X using density-corrected sound velocity values.

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

Abstract: A low salt level sensor comprising a float within a brine tank, apparatus for detecting whether the float has risen in response to the addition of a predetermined amount of water to the brine tank to a height such that an adequate supply of salt is present in said brine tank and apparatus for indicating if the float has not risen high enough. A method of detecting whether the salt level is low in the brine tank of a water treatment system is also described. According to this method, brine is removed from the brine tank and a predetermined amount of water is added. A determination is then made as to whether the brine level has reached a height such that an adequate supply of salt is present in the brine tank and an indication is provided if the brine level is below this height.

Abstract: An arrangement for determining when a fuel tank installed in a boat is full, including (i) a proximity detector for detecting when fuel starts to flow up the vent stack, and (ii) a small reservoir in the vent stack above the proximity detector to prevent fuel from escaping from the stack before the filling of the tank can be halted in response to a warning signal generated in response to the output of the proximity detector.