Abstract: A mass sensoring system for monitoring the amount of fluid in a storage tank with an accuracy high enough to determine both the quantity present and the potential loss of fluid at a loss rate of 0.05 gal/hr or at least 0.1 gal/hr. The system utilizes a pressure sensor positioned at the bottom of the tank and in contact with the fluid. This device includes a bellows unit whose displacement is correlated to changes in the mass of fluid in which it is immersed, and a transducer for monitoring the position of the bellows, wherein the interior of the bellows unit is in the same atmosphere as the sensor, and the sensor is in communication with the vapor pressure immediately above the fluid in the tank. The outside of the bellows is subjected to the stored fluid. A multiple-capsule bellows assembly is coupled to an LDVT transducer in a thermal-expansion-cancelling configuration of the invention.

Abstract: A process for monitoring the coolant level in a cooling system, in particular in a motor vehicle in which the relative pressure and the temperature of the coolant are measured on the high-pressure side of the coolant circuit, using the measured pressure value. A temperature assigned to the pressure value is established on the basis of a coolant specific function (temperature=f (pressure)) and the undercooling of the coolant is then determined by subtracting the measured temperature from the assigned temperature, which undercooling is analyzed as a measure for the coolant level.

Abstract: A liquid monitoring device includes means for detecting the presence of a liquid and means for giving an alarm when the liquid is detected. Preferably a temperature sensor is also provided and the temperature is displayed on an LCD. The temperature sensor is arranged to sense the ambient air temperature at a first sampling rate and then the liquid temperature, after the liquid has been detected by a detector, at a second, more frequent sampling rate. The components are housed in a casing which carries a pivotably mounted sucker for attachment to a wall or bath.

Abstract: In a level measuring device for containers filled with fluid, preferably tanks in tank installations, the fill level height h is determined from the transit time of ultrasound pulses which are emitted by first sound pulse transmitters along a main measuring path extending from the bottom region of the tank to the fluid surface and are reflected from the fluid surface to first sound pulse receivers. Temperature sensors are provided for finding the temperature distribution throughout the fill level height h. Processing the measurements provides a mean temperature TM in the fluid volume. In addition to the main measuring path there is a reference path in the fluid volume, with second sound pulse transmitters and receivers and a reference temperature sensor for measuring a reference temperature T.sub.Ref. The reference path makes it possible to find the sound velocity v*(T.sub.Ref) in the fluid volume at the reference temperature T.sub.

Abstract: An aircraft fuel gauging system has three or more optical pressure sensors 1 and 3 mounted in a tank 10. One sensor 1 is mounted on the floor 14 of the tank, the other sensors 2 and 3 being displaced from the first sensors and from each other in the x, y and z directions. The output of each sensor 1 to 3 is representative of the mass of fuel above the sensor and is supplied to a processor 20. The processor 20 is also connected to an three-axis accelerometer system 21, a pressure sensor 24 above the liquid and a density sensor 25. Utilizing these inputs the processor 20 computes the location of the fuel surface and, from information in the store 22 of tank shape, calculates the mass of fuel.

Abstract: A liquid level and temperature sensing device for monitoring and measuring the level of liquid stored within a tank or reservoir comprising control circuitry to generate and transmit digital level interrogation pulses and a transducer to receive sonic level return signals corresponding to the digital level interrogation pulses and generate corresponding digital level signals and logic circuitry to measure the time lapse between corresponding digital level interrogation pulses and the corresponding digital level signals and a lower sensing probe including an inner conductor coupled to the control circuity to receive the digital level interrogation pulses and a float to float on the liquid within the tank or reservoir including a magnet movable tube to interact with the electromagnetic field generated in the inner conductor by the digital level interrogation pulses to generate the corresponding sonic level return pulses transmitted to the transducer to generate the corresponding digital level signal whereby the

Abstract: A temperature controller with an integral liquid level control is contained within one unit. The unit consists of an electrical and heat conductive housing, which serves as a first electrode of the liquid level sensor. A metal clamp and a means to attach the housing to the liquid vessel is insulated from the housing and serves as a second electrode. The electrodes are connected in an electrical circuit such that when the electrodes are immersed within a conductive liquid, the resistance between the electrodes is reduced and a current is allowed to flow. A temperature sensor, such as a thermistor, RTD, or thermocouple, is contained within the housing. The housing conducts heat from the housing environment for radiation within the housing.

Abstract: Apparatus for detecting leaks in fuel storage tanks. A float suspended in the tank liquid determines liquid levels and transmits the liquid level information via an infrared beam to a probe processor in the upper portion of the tank. The probe processor stores a plurality of level indications for subsequent uploading to an external computer which analyzes the level information to generate leakage rate information.

Abstract: A method and system for measuring the mass quantity and volume of fuel in an aircraft fuel tank is disclosed. A pressure assembly (124) is disposed proximate the lowest portion of each fuel tank on an aircraft (60), with respect to a wing tank (100). The pressure sensor assembly includes a temperature probe (126) having a plurality of temperature sensors (128) mounted therein at spaced apart elevations within the fuel tank. Also included is an attitude sensor (150) in which are provided a roll sensor (156) and a pitch sensor (160) for respectively determining the roll and pitch angles of the fuel surface with respect to a vertical reference axis on the aircraft. The reference axis is aligned with an acceleration-sensitive axis of an accelerometer (164), which is operative to determine the acceleration acting upon fuel within the wing tank, and using the roll and pitch angles, the acceleration normal to the upper surface of the fuel.

Abstract: A probe which mounts in a liquid container has a conductance electrode containing a temperature sensor. A conductance control circuit is coupled to the probe to control an output relay in accordance with predetermined impedance conditions at the probe, and a temperature limit control circuit also controls the output relay in accordance with predetermined temperature conditions at the probe.

Abstract: A microprocessor controlled system and method for automaticaly determining the rate of leakage from a fluid storage tank. The method includes four phases. In Phase #1 the operator manually enters into the system the phase setting, the tank type, the tank material, the tank diameter, the tank volume, and the type of product in the tank. In Phase #2 the operator manually enters into the system the API gravity and the API temperature of the product it the tank. In Phase #3 the microcontroller calculates the thermal coefficient of expansion of the product, and maintains the level of product in a stand tube and computes the product being put in and taken out of the stand tube.

Abstract: Ultrasonic depth measuring equipment comprising a sensor for emitting ultrasonic pulses in a divergent beam and for receiving the echoes of such ultrasonic pulses wherein the sensor is used in a mode such that the ultrasonic pulses are emitted upwardly through a liquid so as to be reflected from a reflecting surface, the echo being received by the sensor, the sensor being coupled to a microprocessor which is adapted to average the time taken between emissions of the pulses and the echo of the pulses being received by the sensor, and from these readings, an accurate measure of the distance between the sensor and the reflecting surface can be made.

Abstract: A temperature controller with an integral liquid level control contained within one unit. The unit consists of an electrical and heat conductive housing, which serves as a first electrode of the liquid level sensor. A metal clamp and a means to attach the housing to the liquid vessel is insulated from the housing and serves as a second electrode. The electrodes are connected in an electrical circuit such that when the electrodes are immersed within a conductive liquid the resistance between the electrodes is reduced and a current is allowed to flow. A temperature sensor, such as, a thermistor, RTD, or thermocouple, is contained within the housing. The housing conducts heat from the housing environment for radiation within the housing.

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

Abstract: The present invention is a combined magnetostrictive linear displacement detector and plural location temperature detector. The combined apparatus produces a composite signal for transmission on a 2 wire transmission line. The resistances of the temperature sensitive resistors as well as two reference resistors are measured in a predetermined sequence. The linear displacement is measured by the length of time required for a torsional strain to travel along the magnetostrictive wire to the position of the magnet. A pulse generator generates a predetermined number of pulses for each resistance measurement having pulse period corresponding to the measured resistance, with the minimum such pulse period preferably being greater than twice the maximum time required for a torsional strain to propagate the length of the magnetostrictive wire. An electrical signal is supplied to the transmission line when either said pulse generator generates a pulse or the induced electrical signal is detected.

Abstract: An oil level sensing apparatus has a body which defines a volume having an open bottom. A float in the volume supports a permanent magnet and moves within the volume in accordance with the oil level therein. A reed-switch is affected by the magnet supported on the float to detect a low oil level. A temperature sensitive plate closes the open bottom of the volume at low temperatures in order to prevent false readings. Additionally, in order to prevent false readings during transient oil level fluctuations at higher oil temperatures, a spring opposes the opening of the plate such that a restriction is formed in the path for draining oil from the volume. This delays the oil drainage from the chamber and any resulting low oil level signal.

Abstract: The level of the surface of a bath of molten metal beneath a fluid layer of slag in a metallurgical vessel is measured by a detector which is moved through the slag layer into the metal bath and then withdrawn. To improve accuracy and to avoid the need for a separate measurement the detector used comprises an oxygen concentration sensor which emits signals indicating the boundary between the molten metal and the slag, whereby the height of said boundary is determined.

Abstract: An extended resistance temperature sensor formed of a plurality of lengths of pre-insulated resistance temperature detector (RTD) wire. The RTD wire is either unheated, self heated or is heated by means of strands of heater wire integrated with or placed closely adjacent to the RTD wire. The RTD wire itself, or together with the heater wire, is bonded together in one embodiment. Alternatively the RTD wire, or with the heater wire, may be encased in insulated shrink tubing, thin wall metal tubing or both. Connectors are provided to supply electrical current for heating purposes or to connect the RTD wire to detection circuitry, or both. Protective sheaths are provided over the connectors.

Abstract: A gauge for detecting both the temperature and surface level of a fluid within a container. The gauge includes an elongated casing which extends into the fluid. A float which rises and falls with the fluid surface is slidably coupled to the casing and carries a magnet. A support member positioned within the casing carries both a sensor for determining the position of the magnet and a sensor for measuring the fluid temperature. The surface level of the fluid can be determined from the position of the magnet. A heat conducting element thermally couples the temperature detecting sensor to the fluid. In a preferred embodiment, the support member takes the form of a printed board. In a separate preferred aspect, the temperature and magnet detecting sensors are reed switches which are vertically spaced apart yet aligned in parallel to minimize interference.

Abstract: A tank leak detection system in which a liquid level multiplier is connected to a differential pressure transmitter one side of which may be piped back into the tank to compensate for internal changes in tank pressure. A capillary having a small bore connects the transmitter and the multiplier to reduce temperature effects. Changes in tank temperature may be sensed, i.e., by a long bulb thermometer and either fed to a temperature transmitter to convert temperature change into a single to a computer used to calculate true tank level and output a signal proportional thereto or fed to the level transmitter to compensate for temperature changes.

Abstract: The instrument for monitoring of the cooling conditions in the reactor core of a light water reactor includes a probe (2), which is introduced into the reactor vessel and comprises a casing (12) made from a low neutron absorbing and water-resistant material, a resistor (11) being hermetically enclosed in the casing (12). The resistor (11) is connected to power supply lines (5). The resistance of the resistor (11) is dependent on the temperature of the resistor. The instrument also includes sensing means providing an output signal, which is dependent on the resistance of the resistor (11), when current flows through the same.In a first mode of operation the monitor is used for detection of a reduction or loss of cooling capacity of the coolant surrounding the probe (2).

Abstract: A microprocessor based fluid tank test management system and method, for measuring the tightness of fluid tanks for leakage. The system includes, an automatic temperature sensing apparatus to measure any temperature change in the fluid during a test period, apparatus for continuously circulating the fluid in the tank, apparatus for stabilizing the geometry of the tank, apparatus for automatically maintaining a constant fluid head in communication with the fluid in the tank and for measuring the fluid added to or removed from the fluid head to keep it constant during the test period, apparatus to determine the coefficient of expansion of the fluid in the tank, and apparatus for utilizing the values of the temperature change, the fluid measurement, and coefficient of expansion, to automatically calculate any fluid leak from the tank during the test period.

Abstract: A mounting head for a resistance tape level sensor is provided which includes a cylindrical outer shell enclosing deformable elastomeric elements surrounding and supporting certain elements of the sensor and clamped to provide high internal compressive forces for sealing all leakage paths.

Abstract: The invention relates to apparatus for measuring storage parameters such as level and temperature relating to immiscible liquids or fluids in a tank. The apparatus comprises a pulse generator (1) for generating pulses which are applied to a delay line (3) with reflected pulses being representative of the depths of the various liquids constituting propagation transitions through different media (I, II, III, IV, etc.). Logic means (Li) are switched on by a measurement pulse (Im) and they are switched off by corresponding reflected pulses (Ii) generated by transitions of order i. Integrator means (Ji) for integrating the signals delivered by the logic means (Li) serve to generate respective voltages proportional to the time lapse between the measurement pulse (Im) and each of the reflected pulses (Ii) under consideration. Multiplexer means serve to sequentially deliver the measured values corresponding to the different liquids of order i in the tank.

Abstract: A water level and temperature detector alarm device and more particularly to an alarm device which includes a buoy type detector to alternately detect water level or water temperature so as to provide an audio alarm signal through a buzzer when water level or water temperature reaches the predetermined range. The detector is connected to the expansible end of a conduit and includes a sleeve having set therein two reed switches and a thermswitch and having mounted thereon a body which includes therein a circular magnet. An alarm device is connected to the other end of the conduit which is having a movable positioning rack mounted thereon for positioning of the whole assembly. Following the rising of water level, the magnet of the buoy alternatively drives the reed switched to turn on the alarm device to buzz or, when water temperature reaches the predetermined range, the thermoswitch will be turned on to drive the alarm device to buzz.

Abstract: A measuring device for determination of the distribution and position of different material compositions, preferably liquids and gases, with the aid of the thermodynamic properties of the material. Through the arrangement of sensor elements as sectors on the inside of a hollow body, it is possible to record the flow direction of the medium being measured at different levels.

Abstract: A filter centrifuge has a feeler arm which contacts the free surface of the centrifuge contents to signify by the angular displacement of the arm, the thickness of the layer of contents in the filter drum. On the contact surface of the filter arm, at least one sensor is provided which is responsive to a characteristic of the material constructed by the arm for signalling the nature of the material.

Abstract: A strip of resistive carbon is deposited on a longitudinal plastic film and a strip of conductive copper is deposited on a second film. The two film strips are glued together with the resistive and conductive strips opposing to form a sealed envelope having a longitudinal cavity. This sandwich is placed in a flexible extruded tube membrane and the whole inserted in a longitudinal slot in a frame, with a channel communicating with the slot and the exterior of the frame. Liquid in a tank compresses the envelope, causing the copper and carbon strips to contract at a point depending on the level. The change in resistance of the carbon-copper circuit with level produces a changing voltage which is processed to provide a signal indicative of the level of in the tank. Temperature sensors in the frame provide the temperature of the at various levels.

Abstract: Apparatus for detecting leaks in fuel storage tanks. A float suspended in the tank liquid determines liquid levels and transmits the liquid level information via an infrared beam to a probe processor in the upper port of the tank. The probe processor stores a plurality of level indications for subsequent uploading to an external computer which analyzes the level information to generate leakage rate information.

Abstract: A method of measuring aircraft fuel quantity and density in a fuel container using an ultrasonic transducer; a stillwell liquid fuel; a computer control, an indicator and an altitude sensor. The computer control includes a central processing unit connected to each of the ultrasonic transducers. The altitude sensor is connected to the central processing unit. The indicator means is connected to the central processing unit. The stillwell is supported by the container. Each ultrasonic transducer is supported within the stillwell by the container. The liquid fuel is supported within the container. An ultrasonic signal is transmitted from the transducer within the stillwell. The reflected ulrasonic signal is received by the transducer within the stillwell. The round-trip time period from sending to reciving the signal is measured. The quantity of fuel in the container is determined from the round-trip time period and stored data on the container volume in the central processing unit.

Abstract: Ultrasonic apparatus for measuring and remotely displaying the amount of liquid in a tank, the amount of water in the tank and the velocity of sound through the liquid in the tank is described with special application to a buried tank containing gasoline with the possibility of water in the bottom of the tank. The apparatus includes an ultrasonic transducer at a fixed distance above the bottom of the tank, a plurality of submerged reflectors vertically arranged at fixed distances above the transducer and a remote console, containing a computer, for activating the transducer and receiving signals of ultrasonic reflections developed by the transducer. Methods are disclosed utilizing the apparatus for computing the height of the liquid (gasoline) level, the depth of the water, if any, the velocity of sound through the gasoline and through the liquid as a whole, and for computing average temperature of the liquid in the tank.

Abstract: Method and apparatus for making depth related measurements from an untethered, gravity driven oceanographic platform. The platform is a smooth streamlined, torpedo shaped body releasably carrying ballast in its nose and covered with syntactic foam for buoyancy. At the appropriate depth, the ballast is released and the body ascends under control of an interferometric homing system which guides it to a recovery vessel. The ballast may be an iron slug held in place electromagnetically.

Abstract: A measurement system for remotely measuring a parameter and relative distance having a parameter sensor providing signals to control the pulse repetition rate of a pulse generator, the pulses from the pulse generator in turn controlling a switch to alternately connect and disconnect an energy storage device to the input of a sonic waveguide device. The output signals at the outputs of the sonic waveguide device control a driving device which provides a representation of these output signals on a transmission line arrangement.

Abstract: Apparatus for monitoring the cooling system of a liquid-cooled automotive engine. The apparatus provides a warning of a malfunction within the system and diagnostic information of what the malfunction is. The compact apparatus is easily mounted in the inlet radiator hose and includes elements for measuring the coolant level, flow rate, pressure and temperature.

Abstract: A manually operable measurement apparatus for measuring level, temperature and transition zone between two different liquids. The measurement is carried out by letting a probe through a sluice and valve means into a tank. The probe is combined in one unit and is sensitive to both relative dielectric constant and loss factor as well as the temperature of the surrounding medium(s) to be measured. The invention is particularly suitable for measurement in tanks having an internal pressure being different from the atmospheric pressure and in explosive environments.

Abstract: An ultrasonic transducer for emitting and receiving sound pulses is mounted within a fluid whose temperature is to be determined. The transducer is disposed in operative association with a first target which is mounted by a bimetallic coil so that it moves in a known manner with respect to the transducer in response to changes in temperature in the fluid. A stationary target is also provided disposed a fixed, known distance from the transducer, for calibration purposes. The transducer is mounted within a fiberglass tube, as are the movable and stationary targets. The tube may be mounted at the bottom of a liquid (e.g. gasoline) storage tank with the transducer facing upwardly so that both the level of liquid within the tank, and the density of the liquid as related to temperature, can be determined utilizing the transducer and a computer for acting upon the transducer output.

Abstract: A device for measuring engine lubricating oil temperature circulating through the oil lubricating system of an internal combustion engine of a motorcycle. Another advantageous embodiment consists of a stem-type thermometer attached to the wall of the oil reservoir with the temperature sensing stem projecting through an appropriate aperture in the oil reservoir wall. In situations wherein the oil reservoir is connected to the internal combustion engine of the motorcycle by an oil carrying conduit, yet another advantageous embodiment can be employed which consists of a branch conduit projecting from the oil carrying conduit with the temperature sensing stem of the thermometer extending axially into the branch conduit. A further advantageous embodiment consists of a stem-type thermometer having markings along the temperature sensing stem corresponding to various oil levels.

Abstract: A device and method for detecting average temperature, particularly adapted for determining the average liquid temperature in an underground horizontally disposed cylindrical tank. The sensing element, in the form of a wire of known temperature versus electrical resistance characteristic is contained within an extensible cylindrical helical coil of plastic tubing which can be introduced into the tank and extended to the overall height of the liquid by gravity through a weight on one end of the coil or by the use of an extendible rod inserted into the center of the coil. The tubing is preformed or arranged relative to the extensible rod to present a greater number of coil turns at the center of the tank to compensate for greater liquid volume.

Abstract: A method and apparatus for testing liquid storage tanks for leakage by using apparatus to measure changes in liquid level and temperature over a predetermined period of time in which the liquid level apparatus includes means for discharging a uniform low pressure to a fixed point below the liquid level in the container and measuring any change in pressures over the predetermined period of time and in which the temperature measuring apparatus includes a liquid filled probe extending for substantially the full depth of the liquid in the tank with any changes in temperature in the probe liquid resulting in an expansion or contraction of the probe liquid with such liquid expansion or contraction being visibly indicated at a sight tube.

Abstract: A system which enables the measuring, testing and accounting for a fluid, preferably oil, as stored in a tank battery adjacent a producing oil well system. In its most basic form, the system includes a master control unit associated with a level transducer for each tank, basic sediment and water monitors for various conduits within the system, temperature sensors for each tank and the various conduits, and a data collection box for transferring data stored in the master control unit after a predetermined amount of time has transpired. Several options are available with this system and these include telemetry options for remote reporting of the various parameters of the system and various alarm and theft prevention devices.

Abstract: Low oil level in an engine crankcase is detected immediately after the ignition switch is turned on by a circuit including the ignition switch, an oil level sensor and a coolant temperature sensor wherein a control circuit generates an output if a low oil level signal is present when the ignition switch is turned on. An enabling circuit allows an output only if the ignition switch has been turned off for a sufficient time period to allow oil drain back to the crankcase. A time delay circuit responsive to coolant temperature and the ignition switch prevents a control circuit output after the ignition switch is turned off for a short period when the temperature is high and a long period when the temperature is low.

Abstract: A test probe for monitoring the level of liquid in a storage container, especially of a flammable liquid, has a guide tube which is inserted through and secured in the threaded hole of a cover of the container. The probe is provided with a magnetic indicating system mounted in part on a bearing which surrounds the tube within the container. Magnetically coupled to the bearing and movable along and within the tube is an electrical contact carriage which makes contact with fingers provided on rolled-on metal tracks provided on non-conductive profiled strips located at least in part in the tube. The strips are reinforced by profiled rails which are located in the tube.

Abstract: This invention relates to a system for sensing the liquid level and coolant properties in a fluid containing vessel by insertion into the vessel of a plurality of matched spaced sensor probes comprising a first and second temperature sensor, the first sensor essentially measuring the media temperature, a heater, an arrangement for applying differential heat between the sensors, the heater and second sensors being thermally connected, all positioned to permit the sensing at the cooling quality of the media present, the heater located directly adjacent the second sensor and adjusted so that when the cooling quality of the normal fluid is sensed the heat generated by the heater and passing into the fluid is virtually completely dissipated and only a small finite differential temperature exists between the sensors and thereby indicates a sub-cooled liquid is present.

Abstract: A device is provided for automatically indicating an insufficient level of oil in a motor-vehicle gearbox of the automatic type. The device includes an oil level sensing system controlling an associated indicator. To prevent spurious operation of the indicator, the device is provided with a number of sensors arranged to ensure that the oil-level sensing system can only effect control of the indicator under certain predetermined conditions including that the vehicle is stationary and on the level, and that the engine is idling. An oil temperature sensor is also provided either to prevent operation of the indictor if the oil temperature is outside a predetermined range, or to effect a temperature dependent adjustment of the acceptable value of oil level.

Abstract: An apparatus for the continuous and direct measurement of the temperature of the upper superficial layer of the surface of the sea or other water surface, which apparatus comprises a central floating member and at least one arm connecting the central member to at least one peripheral floating element, the or each arm containing a thermal collector for transmitting heat to at least one temperature detector carried by the apparatus, wherein the central member and the peripheral floating element are adapted to maintain the apparatus on the water surface while at least a part of the or each arm is in contact with and senses the upper superficial layer of the water, and wherein electrical means are provided in the apparatus for the storage and/or transmission of temperature data from the or each temperature detector.

Abstract: An underground storage tank is filled with liquid (e.g., gasoline) until the level of the liquid in the tank rises into the fill-pipe leading from the surface of the ground to interior of the tank. The change in elevation of the liquid in the fill-pipe is monitored over a period of time. The temperature of the liquid within the tank is monitored over the same period of time. Evaporation from the surface of the liquid in the fill-pipe is monitored over the same period of time. A change in elevation of the liquid in the fill-pipe below the level caused by expansion or contraction due to temperature change, and by evaporation loss, indicates a leak in the tank.

Abstract: A liquid gauge for measuring liquid level in a container having a differential pressure transducer positioned in the liquid. The transducer has a first port exposed to liquid adjacent the bottom of the container and a second port in communication with the environment above the liquid. The gauge may include a water level detector and a temperature measuring transducer. The gauge will measure the hydrostatic pressure of the liquid which is a determination of the liquid level and/or volume.

Abstract: A device for electric monitoring of the level of a liquid present in a container, with a temperature-dependent resistance probe which is immersed in the liquid the level of which is to be monitored, a source of constant current connectable, controlled by a timer, to the resistance probe, a circuit, controlled by the timer, for detecting and storing an initial voltage drop on the resistance probe at an initial time and a measurement voltage at a defined time after the connection of the source of constant current, and a circuit for evaluating these voltages by subtraction of the measurement voltage from the initial voltage and if necessary under circumstances inversion of the difference in order to form a display voltage which corresponds to the level.

Abstract: Apparatus for externally determining the level of a mass of flowable material such as liquid or granular material contained in a closed or sealed container having walls of magnetic material includes an elongate strip of thin magnetized metal sheet material coated with a thermochromic substance which varies chromatically with variations in temperature. The elongated strip is applied to the outer surface of the wall of the container in heat conducting relationship thereto by magnetic attraction and extends along the height of the container. The container is exposed to a temperature change either natural, such as that which occurs at sunset and sunrise, or artificially induced. Because of the difference in the rate of heat conduction of the void volume and the filled space of the container, the container wall experiences a temperature gradient which is most pronounced at the interface of the contents and the void space. The temperature of the container wall changes abruptly at the surface of the contents.

Abstract: Instruments measure and periodically store coke vertical temperature profile data sets at multiple coke guide levels within expected level range. Computer detects highest level in each data set above a reference temperature and terminal plots coke level as a function thereof.