A fluid sensor system detects one or more performance characteristics of a heating system that heats a fluid. The sensor system includes a probe having a finite length a portion of which is to be immersed in the fluid. The probe includes a resistive heating element and a fluid temperature sensor for measuring one or more performance characteristics, wherein the fluid temperature sensor is configured to measure a fluid temperature, and the resistive heating element is operable as a heater to create a temperature differential between the fluid and air to detect the fluid, and as a sensor to measure a fluid level.

A method of sensing a fluid. The method includes determining a slope based on a first measurement of a first ultrasonic pulse traveling through the fluid, a second measurement based on a second ultrasonic pulse traveling through the fluid, a first temperature of the fluid, and a second temperature of the fluid. The method further includes comparing the slope to a predetermined slope and the first measurement to a predetermined measurement.

A compressor may include a shell containing a motor, a compression mechanism and a lubricant sump. The compressor may also include first and second temperature sensors, and a control module. The first temperature sensor may be at least partially disposed within the lubricant sump and may measure a first temperature of a lubricant at a first position. The second temperature sensor may be at least partially disposed within the lubricant sump and may measure a second temperature of the lubricant at a second position that is vertically higher than the first position. The control module is in communication with the first and second temperature sensors. The control module may determine a first difference between the first temperature and the second temperature. The control module may determine whether a liquid level of the lubricant in the lubricant sump is below a predetermined level based on the first difference.

In some examples, a liquid container comprises a chamber forming a volume containing a liquid, an elongated strip extending into the volume containing the liquid, the strip supported along a side of the volume such that a face of the strip adjacent the side of the volume is not opposed by the liquid, a plurality of heaters supported by the strip along the strip, and a plurality of temperature sensors supported by the strip along the strip.

A compressor includes a shell, a first temperature sensor, a second temperature sensor, and a control module. The shell includes a motor, a compression mechanism and a lubricant sump. The first temperature sensor is at least partially disposed within the shell and configured to measure a first temperature of a lubricant at a first position. The second temperature sensor is at least partially disposed within the shell and configured to measure a second temperature of the lubricant at a second position that is vertically higher than the first position. The control module is in communication with the first and second temperature sensors and configured to determine a first difference between the first temperature and the second temperature. The control module is configured to determine whether a liquid level of the lubricant in the lubricant sump is below a predetermined level based on the first difference.

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 device to detect engine oil level and temperature. The device comprises: a thermistor; an unregulated, or voltage-only regulated, power supply configured to provide a non-continuous high current to the thermistor for a predetermined time in order to induce self-heating of the thermistor. An ADC (Analog-Digital Converter) configured to read a voltage across the thermistor before and after the heating of the thermistor. A processor is configured to calculate a change in temperature of the thermistor on the basis of a change in voltage measured by the ADC, and, thereby, deduce an engine oil level and temperature.

An apparatus and method for measuring the level of a liquid. The apparatus includes an elongated probe comprising an electrically and thermally conductive material. The probe has 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. Electrical circuitry may be used to control and receive signals from the various components and to measure the electrical resistance between a location in the upper region of the probe and a location in the lower region of the probe. The liquid level may be computed as a function of the measured values, the probe dimensions, and the known temperature dependence of the electrical resistance of the probe.

Described is a method and system for a level measurement. An echo curve is analyzed, and both the level and the moisture content of the stored material is determined therefrom. The level measuring instrument works in such an energy-saving manner that it is sufficient to supply the instrument with power using a 4 . . . 20 mA two-wire conductor loop that is also used to transmit at least some of the measured values.

The invention is a hydrogen generator with a fuel gauge and a method of fuel gauging. The hydrogen generator includes a replaceable fuel unit, containing a hydrogen-containing material (fuel) that can release hydrogen gas when heated and whose thermal conductivity is related to a quantity of releasable hydrogen contained therein, and a fuel gauge including a heat source and a temperature sensor adjacent to the fuel unit and a controller for determining a fuel level value based on a measured temperature. The temperature is measured at a pre-established time after activating the heat source, and the measured temperature is compared to a predetermined relationship between the measured temperature and a releasable hydrogen content in the fuel at the pre-established time. An output signal is provided (e.g., to a visible display, an audible signal or a controller).