Abstract: A sensor which is installed in a waste tank to determine when the tank is full includes a shroud having a body with a curved surface and a leading edge which is mounted flushly to the inner surface of the tank wall and a trailing edge which is spaced apart from the sensor face. As waste material is swirled about the inside surface of the tank wall, the shroud causes the waste material to be transported above the sensor face without disrupting the flow of the waste material along the tank wall. The cover is sized and configured appropriately to allow convenient rinsing when the waste tank is emptied.

Abstract: A cleaning device for contact lenses includes a housing having a cleaning chamber, a stirring device for generating a liquid flow within the cleaning chamber, a heating device for boiling a liquid in the cleaning chamber, a feeding device for feeding the liquid into the cleaning chamber, a discharging device, a feeding amount detecting device for detecting a feeding amount of the liquid which is fed into the cleaning chamber, an operation controlling device for giving a signal to the stirring device, the heating device, the feeding device and the discharging device in response to the feeding amount of the liquid detected by the feeding amount detecting device, respectively and for performing a cleaning process, plural rinsing processes and a boil process.

Abstract: A vacuum priming system for drawing liquid into the pumping chamber to prime a vertical shaft centrifugal pump for pumping sewage or the like. The vacuum priming system includes a priming pump for developing a partial vacuum in the pumping chamber and causing liquid to be drawn into the pumping chamber to evacuate air therefrom. A sensor is provided for detecting the interface between the liquid and air in an area in or above the pumping chamber for activating and deactivating the priming pump. The sensor comprises a low sensitivity capacitive proximity sensor having a generally vertical sensing face for sensing the relative movement of the interface between the liquid and air.

Abstract: There is provided a system for blocking the inflow of water to an appliance such as a hot water tank in the event of a leak in the appliance or water supply thereto. A low voltage current solenoid selectively blocks said inflow in response to a leak. No current is drawn during normal operation of the appliance.

Abstract: A fluid level controller flexibly set up according to the number of level steps to be controlled and the pitch between such level steps, which comprises a plurality of joint pipes connected in series to form a pipe assembly; a ring-shaped magnetic floating member sleeved on such a pipe assembly to follow fluid level to move up and down; a plurality of reed elements having each a reed switch connected in series with one another and received in the joint pipes; a main control circuit comprising latching relays in quantity one less than the quantity of the reed elements and a plurality of controlled actuators respectively connected to the reed elements.

Abstract: A control for a water distillation apparatus admits untreated feed water to the boiling tank in response to a demand for the production of distilled water and operates the heater to produce steam. Level probes in the boiling tank monitors the level of untreated water in the boiling tank and admits more feed water as necessary. When demand for production of distilled water has ceased, the heater is deenergized and the boiling tank is filled to dilute the residual water in the tank and lower its temperature prior to drainage to prevent damage to a plastic house drain. In a preferred embodiment, feed water is admitted to the boiling tank in large batches and the production of distilled water continues uninterrupted until the entire batch is distilled to conserve heat energy even if demand ceases during such batch distillation. A cleaning mode is provided to remove scale from the interior of the boiling tank with a simplified manual cleaning procedure.

Abstract: A processor controlled supervisory apparatus for a liquid level controller of a feedwater heater obtains DCA characteristics and breakpoints thereof in a programmed manner. A plurality of DCA characteristics are obtained for a plurality of load conditions, and the breakpoints and other operating parameters are stored in a database correlating operation parameters with load conditions. Equations describing the relationship between the parameters and the load conditions are determined by the programmed processor and additional data points determined therefrom to provide load-responsive control for liquid level setpoint. A retrofitting apparatus retrofits the inventive supervisory control apparatus onto existing liquid level controllers.

Abstract: A distillation type of water purification system has a raw water inlet valve for admitting raw water continuously to a boiling tank at a rate greater than the rate at which raw water is converted to treated water. A drain valve located at the bottom of the boiling tank is energized by a raw water level sensing means whenever the raw water level reaches a predetermined level, to discharge water from the boiling tank. Treated water is stored in a storage tank having a pump for discharging treated water to the user upon demand. A single conductivity sensor in the storage tank controls the pump to allow it to operate only if the sensed conductivity is above a first predetermined value but not at or above a second predetermined value greater than the first value. An improved condenser has two sets of tubes, each set is arranged in a pair of planes oriented transverse the flow of cooling air with the tubes parallel. The internal cross-sectional area of one set is about twice that of the other.

Abstract: In a so-called condensate trap for discharging condensate, e.g. oil or water from a fluid system which contains air or a gas or vapor under pressure, a single tube which projects into a housing in which the condensate collects contains spaced sensors of an electric capacitive type sensing the maximum level which the condensate is to be allowed to reach within the chamber and a predetermined lower level. A signal from the upper sensor triggers a pilot valve which opens a diaphragm-type discharge valve and a signal from the lower sensor initiates closing of the valve, but only after a time delay, allowing the condensate to fall first to a level below that of the lower sensor. This time delay is related to the time taken for the condensate to fall from the maximum level to that of the lower sensor. The control unit and sensor tube form a self-contained structural assembly for easy installation and replacement.

Abstract: The present invention relates to a method of cleaning a pipe system (3) in baths, preferably bath tubs, through which pipe system water and/or air is led into the bathwater (6) of the bath (1) to produce water currents and/or water/air currents (4) and/or air bubbles (5) therein. For effective cleaning, the pipe system (3) is flushed with pure water (31) after a bath has been taken before impurities in said pipe system have/had time to dry. A suitable apparatus for carrying out said method comprises a sensor (49) which is adapted to sense when bathing in the bath (1) has been concluded and to deliver when the bathing has been concluded a signal to a time lag relay (34) which is adapted to open a valve (33) for supply of flushing water (31) to a flushing device (30) for flushing of the pipe system (3) a certain time after the time lag relay (34) has received said signal from the sensor (49).

Abstract: A trough surrounding the base of a machine for trapping the spilled chemical and draining it into a pit in which a pump is located that is automatically engaged to pump the spilled chemical into a closed holding tank. A vapor detecting device will, upon the detection of toxic vapors, automatically turn on a ventilation system that will remove vapors from the area of the trough and from an optional isolation tent surrounding the machine and force the vapors through a filter having a bed of charcoal for absorbing the toxic vapors from the air. The filtered air is then vented to the atmosphere. A splash curtain is also used to direct the spilled chemicals into the trough. A substantial portion of the apparatus may be molded as a single unit or as separate sections that may be readily assembled and fixed into a unit at the installation site.

Abstract: A modular water distillation apparatus includes a distillation unit which may be manually operated by adding water manually to the steam generator. The apparatus further includes an add-on holding tank and an add-on control unit which mounts to the holding tank and provides automatic control of the distillation unit by providing feedwater to the steam generator when the steam generator is deenergized and the holding tank is not full. The add-on control further includes a power receptacle for an add-on distilled water demand pump.

Abstract: A circuit configuration for regulating the filling and refilling of containers with liquids, such as a carbonator vessel, and comprises a liquid container and an electronic circuit for reading the liquid level in the container at a single level and generating a level signal corresponding to the liquid level sensed, and in the event the level falls below a predetermined level, causes a flow regulator controlled by a timer to provide a refilling with an overshoot so as to permit the liquid level to rise to a second predetermined level above the first predetermined level so that the volume of the head space and pressure within the container is held substantially constant.

Abstract: A collection basin for collecting leakage from an automatic dishwashing machine. A drain or pump may be provided for removing the leakage collecting in the basin. Flanges extending along the sidewalls of the basin in combination with the sidewalls facilitate installation and removal of the dishwashing machine by guiding the machine support legs.

Abstract: A distillation type of water purification system has a raw water inlet valve for admitting raw water continuously to a boiling tank at a rate greater than the rate at which raw water is converted to treated water. A drain valve located at the bottom of the boiling tank is energized by a raw water level sensing device whenever the raw water level reaches a predetermined level, to discharge water from the boiling tank. Treated water is stored in a storage tank having a pump for discharging treated water to the user upon demand. A single conductivity sensor in the storage tank controls the pump to allow it to operate only if the sensed conductivity is above a first predetermined value but not at or above a second predetermined value greater than the first value. An improved condenser has two sets of tubes, each set is arranged in a pair of planes oriented transverse the flow of cooling air with the tubes parallel. The internal cross-sectional area of one set is about twice that of the other.

Abstract: An electronic level control structure for regulating a fluid level in a vessel, such as a humidifier tank. The electronic level control has at least two Teflon.RTM. coated probes for sensing fluid level in the tank and extending downwardly from a main body member. A downwardly extending sleeve positions about a portion of the upper regions of each of the probes. The Teflon.RTM. coating and the sleeve at the upper region of each probe inhibits the formation of scale between the probes at the upper end of each probe by preventing or minimizing the amount of contact by vaporous gases, mineral salts and other contaminants about the upper regions of each probe. This also prevents buildup of electrical conductive scale. In one embodiment, three probes of different lengths extend downwardly from a body member.

Abstract: An electronic control and dosing system for desalinators (10) has a baffle, disposed between the evaporation and condensation chambers, fitted with probes (70, 71) which detect the presence of liquid created by entrained bubbles, that pass through the holes in the baffle. A control circuit (72), connected to the probes (70,71), closes a solenoid valve (62) to shut off the supply of feed water to the desalinator (10) until the threat of entrainment has passed. A foaming and/or scale inhibiting polymer, contained in a tank (64), is periodically introduced to the feed water inlet line (63) by a solenoid valve (65) controlled by a timer circuit (66).

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

Abstract: The present invention relates to a method of cleaning a pipe system (3) in baths, preferably bath tubs, through which pipe system water and/or air is led into the bath-water (6) of the bath (1) to produce water currents and/or water/air currents (4) and/or air bubbles (5) therein. For effective cleaning, the pipe system (3) is flushed with pure water (31) after a bath has been taken before impurities in said pipe system have/had time to dry. A suitable apparatus for carrying out said method comprises a sensor (49) which is adapted to sense when bathing in the bath (1) has been concluded and to deliver when the bathing has been concluded a signal to a time lag relay (34) which is adapted to open a valve (33) for supply of flushing water (31) to a flushing device (30) for flushing of the pipe system (3) a certain time after the time lag relay (34) has received said signal from the sensor (49).

Abstract: In a drainage system for maintaining a swimming pool cover drained of accumulated precipitation, a pump with its intake is disposed in a fluid trap defined by an upper surface of the swimming pool cover. A discharge port of the pump is disposed outside of the fluid trap. A sensor is disposed in a flow path of the pump for detecting the presence of fluid flow therethrough, while a clock unit is operatively connected to the pump for periodically operating the pump for a ten-second interval. A control circuit continues to operate the pump beyond the ten-second interval upon the detection by the sensor of fluid flow through the pump at the end of the ten-second interval. In that case, operation of the pump is terminated only upon a cease of fluid flow through the pump.

Abstract: A system for monitoring ink flow from an ink storage tank to at least one ink fountain of a high-speed, web-fed printing press employing a scale for measuring the weight of the ink storage tank and comparing weight signals from the scale at successive times to determine the weight of ink consumed over the interval between readings. A pump is associated with the storage tank for pumping the ink to the fountain via coupling lines. An ink level sensor detects the level of ink in the fountain and provides an ink demand signal for operating a valve means in the ink coupling line to in turn cause ink flow to the fountain so as to provide replenishment of ink thereat. With the use of plural fountains, means are provided for prioritizing delivery to the fountains so that individual ink consumption on a per fountain basis can be determined. In this regard, the system also employs a volume sensor preferably in the form of a pump stroke position sensor for determining incremental weight delivery per stroke.

Abstract: An apparatus for detecting circulating liquid flow in a machine for automatically processing a photographic light-sensitive material is disclosed in which a branch pipe opened at a position higher than a liquid level of a processing liquid is vertically provided on the suction side of a circulating pump of a processing liquid circulating system provided outside a processing tank for circulating the processing liquid in the processing tank. A liquid level detecting electrode is provided in said opening portion so that the lower end of the electrode is positioned on the same level as or a position a little lower than the liquid level of the processing tank. A contact electrode is provided so as to be in contact with the processing liquid.

Abstract: A liquid mixing system and method are disclosed for automatically preparing a batch mixture containing predetermined quantities of liquids such as spray dampening solutions or silicone emulsions used in the printing industry. The system comprises a holding tank having one or more liquid columns in liquid communication with the tank so that the level of liquid in the column, or columns, will be the same as the level of the liquid in the tank. Liquid level detection devices preferably in the form of static capacity-type proximity switches sense the level of the liquid in the column, or columns, and liquid charging devices responsive to the liquid level detection devices charges the liquids into the tank in seriatum each time raising the level of the liquid in the tank and in the columns to the next detected level.

Abstract: A water tower consisting of a main body extending upward from the ground, a water channel and a pumping means for pumping water into the water channel, which acts as a water storage of the tower. In know water towers, the main water storage is placed at the top of the tower, at a height of several tens of meters, which means that the costs of construction on the tower and its groundwork are considerable and impose strict requirements on the structure of the tower. These problems are solved by the invention in that the tower is provided with a water reservoir placed at its lower end under the ground surface or substantially close to the ground surface, said reservoir constituting a safety storage of water, and that the water channel of the tower is of a substantially narrow sectional form through the whole of its length.

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

Abstract: A ground fault interrupter (GFI) circuit is wired to a main circuit breaker panel. A first output of the ground fault interrupter circuit provides electrical current to a solenoid valve that controls the supply of cold water to a conventional hot water heater. The solenoid valve is held in its open position by 110 V. alternating current and is closed by spring biasing means when the current is cut off. The other output of the GFI circuit provides 110 V. alternating current to a leak detector. A leak detecting system directs leakage to a collector wherein the presence of water in the collector completes the circuit between the hot wire and ground of the second outlet. When the circuit is shorted out to ground by the presence of water the GFI circuit is tripped at the main circuit breaker panel and simultaneously cuts off current to the solenoid valve controlling the flow of water to the heater permitting the spring to bias the valve shut and preventing any water damage due to leakage.

Abstract: Basement flooding due inter alia, to drain overflow or sump pump failure is a common problem. An apparatus for solving the problem includes a cover for closing a basement floor drain, a tubular casing extending through the cover into the drain, a pair of spaced apart conductors in the casing for completing an electrical circuit when water rises through the open bottom end of the casing to a predetermined level, and a control circuit connected to the conductors and to a solenoid valve in the building water supply pipe for closing the latter, so that no additional water enters the drain to exacerbate an already bad condition. A second pair of spaced apart conductors on the floor of the basement is coupled to the control circuit to give the same response in the presence of floor moisture. An audible alarm is sounded as part of the response to detected water.

Abstract: A protection device for the compressor of an air conditioning system. The protection device comprises a refrigerant level detector positioned in a receiver dryer to detect the level of refrigerant. A control device is coupled to the level detector and prevents the operation of the compressor if the level of refrigerant is below a predetermined amount.

Abstract: Acoustic signals are transmitted through the fluid flow of a fuel delivery pump to a tank to be filled. From reflection signals the fluid level in the tank is detected and a timely disconnection of the pump can be effected in order to prevent fuel losses.

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

Abstract: An apparatus for automatically selectively introducing successive samples of a liquid from at least one pressurized line into a receiving funnel having an outlet port and at least one inlet port. The receiving funnel has main receiving chamber for receiving liquid samples and a sensing device is also provided in the receiving funnel for sensing the level of liquid present in the receiving funnel for controlling flow in and out of the funnel.

Abstract: A fluid controller for a fluid supply system such as the plumbing supply system for a bathroom comprises hot and cold fluid temperature sensors and flow sensors which are installed in respective ones of the hot and cold fluid supply pipes upstream of the fluid discharge outlet. Hot and cold fluid flow control valves operated by valve motors are also installed in such pipes. The sensors and motors are connected to a microprocessor including a comparator means which is operative to compare values programmed in a memory means with signals received from the sensors so as to generate control signals for the motors so as to obtain a desired fluid temperature and flow rate at the discharge outlet. The controller can be installed in an existing plumbing system without disturbing the existing faucets and manual control valves. Alternatively, the controller can be used in a new installation with or without manual control valves.

Abstract: A beverage dispenser has a housing, a dispenser head with an electrically conductive combination cup actuator lever and beverage level probe, a control circuit connected to the probe and to a start switch actuatable by the probe and to a solenoid for a beverage valve, and a drip tray and cup rest wherein the cup rest is tilted rearward toward the actuator lever to hold a cup against the lever and keep the back of the cup rim against the lever. An improved actuator lever has a dielectric journal, an electrically conductive thin wall metal tube cantilevered probe extending down from a single fastener securing a control lead and the probe to the journal piece and the conductive probe is spaced from and is below the level of the valve body and lever fulcrum. A conductive plastic flow control is mounted in the valve body and a second control lead is connected to the electrically conductive flow control for providing a potential signal in the beverage.

Abstract: A device for detecting the filling condition in a container has an electro-mechanical transducer 4 secured on a diaphragm 5, by which transducer the diaphragm 5 is set in vibration. An electrical unit energizes the transducer to produce oscillations of the diaphragm 5. The diaphragm 5 has a holder 1 on which the diaphragm 5 is fastened by means of a cylindrical intermediate member 6. The wall thickness of the cylindrical member 6 is a multiple of the thickness of the diaphragm 5.

Abstract: A monitoring assembly (20) which has a plurality of sensors (24) arranged in spaced relationship along a body (23) which may be suspended from a coded multicore cable (25) in a reservoir to monitor liquid levels therein. Each sensor (24) is connected to a respective coded core (43) of the multicore cable (25) such that any sensor (24) may be selectively coupled to remote control apparatus.

Abstract: An ink jet recording apparatus has a recording head for discharging ink and effecting recording, a recording flow path communicating the recording head with one end of a first ink tank, a pump side flow path communicating the first ink tank with the recording head through a pump and, together with the recording flow path, constituting an ink circulation path through the head and the first ink tank, and a secnd ink tank for supplying ink to the first ink tank. Normally open electrical opening-closing means (FIG. 11) are provided in the recording flow path and in a tube for opening the first ink tank to atmosphere. Another normally open electrical opening-closing means and a check valve permitting the passage of ink from the pump only to the recording head, this latter opening-closing means and the check valve being interposed in series in the pump side flow path between the pump and the recording head. The apparatus also may include an overflow sensor (FIGS.

Abstract: A device for detecting a filling level in a container having an electro-mechanical transducer 4 which is secured to a diaphragm 5 for vibrating the diaphragm 5. Furthermore an electrical device is provided for activating the oscillations of the diaphragm 5. The diaphragm 5 has a holder 1 on which the diaphragm is fastened by means of a cylindrical intermediate member 6. The holder 1 has a holder projection 7 which, with play, is enclosed and engaged by the cylindrical intermediate member 6. The intermediate member 6 is disposed on the holder projection 7 by an elastic play equalization element which is located between the holder projection 7 and the intermediate member 6.

Abstract: In a device for detecting filling level of liquid in a container, a protective tube (6) extends over a membrane (5) which can be placed in vibration by an electromechanical transducer (4). In this way, bubbles which rise in the liquid cannot reach the membrane and induce a false measurement of low filling level.

Abstract: In connection with a beverage dispensing machine, an automatic self-fill control apparatus for the machine for controlling the filling of the liquid tank, which liquid tank is fed with a combination of water and a concentrate syrup adapted to be mixed with the water within the tank. A sensor member is disposed in the tank in a position so as to be responsive to the rise and fall of liquid in the tank. Pump means are provided adapted to pump the syrup to the tank. Control of water flow to the tank is also carried out. The sensor member has a low probe for detecting a low predetermined level of liquid in the tank and a high probe for detecting a high predetermined level of liquid in the tank and adapted to respectively generate low and high probe signals.

Abstract: An easily viewed control panel structure indicating the status of and controlling the operation of a water, wastewater or process liquid pumping station where the pumping equipment is operated automatically with respect to a varying liquid level or pressure, liquid level is sensed over a calibrated range, the sensed level information is sent to a controller as a proportional signal, the value of the level of pressure information is displayed on a multi-element, vertically-oriented light-emitting diode bar graph display with each element representing a uniform increment of the total level or pressure range, a circuit-connecting programming pin is inserted in each of several vertically positioned receptacles of the control panel with each such insertion at each horizontal level representing a segment of the level display bar graph, with each receptacle representing a turn-ON or turn-OFF capability of the controller and with two such receptacle circuits combining to provide differential level automatic control o

Abstract: In an expanded bed reactor, the expansion of the bed is automatically controlled by automatically changing the rate of speed of a recycle pump for the reactor. The bed is preferably provided with both high and low level bed detectors, and a further detector for determining abnormally high levels.

Abstract: A water level controller for a boiler has electrical probe means (capacitive or conductive) to be arranged in the boiler to detect electrically the water level therein. An oscillator circuit generates an oscillator signal which first and second circuit means receive. When a capacitance probe is used, the first circuit means has a variable gain amplifier in which the gain is determined by variations in the capacitance of the probe according to the water level. The second circuit means comprises a variable gain amplifier in which the gain is determined by a variable resistance the value of which is representative of the desired operating water level. Third circuit means obtains a difference signal resultant from the output signals of said first and second circuit means, which is representative of the difference between the actual water level in the boiler and the desired operating level of the water in the boiler. Relays open and close the water supply respectively.

Abstract: An apparatus for controlling liquid level, comprising containment means for containing and dispensing liquid, flow varying means operable for varying flow of liquid into the containment means, stepper motor means for operating the flow varying means, sensor means for sensing level of liquid in the containment means, and PDD controller means connected between the sensor means and the stepper motor means for controlling liquid level.

Abstract: An assembly for collecting and disposing of waste solvents in a manner to meet safety requirements of municipalities. The assembly includes a waste tank and an open-top container for receiving and supporting the waste tank. The container has a greater internal volume that does the waste tank so that, when the waste tank is in the container, a space surrounds the waste tank. Such space is adapted to receive and trap any leakage or overflow of the solvent from the waste tank during use of the assembly. The waste tank has a first port for receiving waste solvent and a second port for allowing the waste solvent to be pumped out of the waste tank. Liquid level sensors are provided on the waste tank for sensing the solvent therein at different levels. The container has brackets for positioning the waste tank on the bottom of the container, and the container has casters to allow the assembly to be easily shifted from place to place.

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 automatic freeze control (10) includes a temperature sensor (18) and a valve (20) connected to the water line (22). Control circuitry (36, 38, 40, 42, 44 and 46) is responsive to the line water temperature continuously monitored by the sensor (18) to selectively open the valve (20) for increased periodic flow with decreasing temperature.

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: 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: There is disclosed a system for automatically closing a gate valve of the type customarily installed in a sewer pipe system, the gate valve being positioned such as to divide the pipe into a forward exit section and a rear exit section, the system including fluid sensing means positioned in the forward exit section of the pipe adapted to sense the fluid level, a two phase motor having a forward phase and a reverse phase operationally associated with the gate valve for alternately opening and closing the gate valve, electrical means interconnecting the fluid sensing means and the motor to activate the motor in response to the fluid level sensed by the fluid sensing means, the motor including switch activation means associated therewith and mounted for arcuate movement about a pivot point, and switch means for alternately controlling the forward and reverse phases of the motor, the switch means being mounted in position within the arcuate path of travel of the switch activation means.

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.