Disclosed are a water storage tank and a method for controlling the full water level thereof. The water storage tank according to one embodiment of the present invention comprises: a tank main body for storing water which flows in through a water inlet and discharging water through an outlet; and a control unit for controlling inflow and outflow of water into and from the tank main body, wherein the control unit can change the height of the full water level of the tank main body according to a user's selection or the degree of water discharge from the tank main body.

An MgB.sub.2-based superconducting wire for a liquid hydrogen fluid level sensor which can maintain an unimmersed portion of the MgB.sub.2-based superconducting wire for a liquid hydrogen fluid level sensor in a non-superconducting state even without heating the unimmersed portion is provided. A wire for a liquid hydrogen fluid level sensor comprises an MgB.sub.2-based superconductor which contains Mg, B, and Al. The critical temperature at which the electrical resistance becomes essentially zero is 20-25 K, and the transition width, which is the difference between the temperature at which the electrical resistance begins to decrease toward zero and the critical temperature, is at most 5 K.

A liquid reservoir includes at least one liquid surface level detection unit in the liquid reservoir. The at least one liquid surface level detection unit includes a plurality of liquid surface level detection units. The plurality of liquid surface level detection units each include a plurality of self-heating sensors. The plurality of self-heating sensors are positioned at different heights.

Examples provide a series of heaters supported at different depths within the volume. A series of temperature sensors is supported at different depths within the volume. The temperature sensors output signals indicative of dissipation of heat from the heaters to indicate a level of the liquid within the volume.

A unit which combines a remotely programmable controller with an integral temperature and level sensor for controlling the temperature and level of a given liquid. The device comprises one temperature sensor, to measure a liquid's temperature and to provide an electrical output; one level sensor, to measure a liquid's level and provide an electrical output; a programmable scaling and control module, for receiving the electrical outputs of the temperature sensor and level sensor as input signals, for scaling the temperature signal as a function of temperature and a scale-selection input, and for implementing a control logic to process the sensor signals into two respective control signals; two electronic switching devices, to electrically interface one of the two control signals to an external heater or cooling unit and the other one of the two control signals to an auxiliary device, such as a pump or alarm.

An apparatus and method for measuring the level of a liquid. The apparatus comprises an elongated, thermally conductive probe with an upper region to be disposed above the surface of the liquid, a lower region to be disposed below the surface of the liquid, and a middle region. A heater adds heat to the probe, and temperature sensors may measure the temperature of the probe in the upper and lower regions. An actuator may introduce a vibration into the probe at a first location, and a vibration sensor senses the arrival of the vibration at a second location. Electrical circuitry controls may be used to receive signals and make measurements. The liquid level may be computed by electrical circuitry controls via an equation.

A compressor may include a shell, a compression mechanism, first and second temperature sensors, and a control module. The shell may define a lubricant sump. The compression mechanism may be disposed within the shell and may be operable to compress a working fluid. The first temperature sensor may be at least partially disposed within the shell at a first position. The second temperature sensor may be at least partially disposed within the shell at a second position that is vertically higher than the first position. The control module may be in communication with the first and second temperature sensors and the pressure sensor and may determine whether a liquid level in the lubricant sump is below a predetermined level based on data received from the first and second temperature sensors.

A temperature and electrolyte sensor for a battery includes a probe that is electrically conductive and thermally conductive and configured to be disposed in a liquid electrolyte of the battery. The sensor further includes a thermal coupler coupled to the probe, a temperature determination circuit electrically thermally coupled to the probe and configured to output a signal indicative of a temperature of the probe, and a fluid detection circuit electrically coupled to the thermal coupler and configured to output a signal indicative of a presence of the liquid on the probe. The temperature determination circuit and fluid detection circuit may be disposed in a housing of the sensor, and the probe may extend from the housing.

Examples provide a series of heaters supported at different depths within the volume. A series of temperature sensors is supported at different depths within the volume. The temperature sensors output signals indicative of dissipation of heat from the heaters to indicate a level of the liquid within the volume.

A heater system includes an integrated heater device and a control system. The integrated heater device includes a thermocouple for measuring temperature and one or more multiportion resistive elements that are operable as heaters to create a temperature differential between the fluid and air to detect the fluid, and as sensors to measure a fluid level. The control device operates the integrated heater device as a sensor or heater based on one or more performance characteristics of the heater system and self-calibrates the heater device.