Abstract: A rodless guide microwave radiation device, system, and method is disclosed for measuring at least one characteristic of a liquid in a vessel. A hollow metal waveguide conveys microwave radiation and is adapted to be disposed in a vessel for containing a liquid, the waveguide having a first end and a second end. A single chip radar sensor mounted on a PCB is disposed proximal to the first end of the hollow waveguide. The radar sensor is configured to transmit millimeter wavelength signals into the first end of the hollow waveguide for propagating down the waveguide toward the second end, and receive a return echo from the signal based upon a change in impedance upon encountering the liquid and propagating in the reverse direction of the waveguide, the single chip radar sensor including electronic circuitry for determining at least one characteristic of the liquid located in the waveguide based on detection of an impedance change according to time domain reflectometry.

Abstract: An intrinsically safe cellular tank level monitor for use with consumer LP storage tanks is provided. The cellular monitor is adapted to read the LP storage tank gauge and transmit the level information through a cellular network to a data center. The data center may be part of or may communicate with a fuel delivery service company serving the residential consumer. The cellular monitor is a smart device that allows two-way communication over the cellular network. Control logic within the cellular monitor controls transmission of data to the data center as well as the determination and transmission of alarm conditions as determined by the local cellular monitor.

Abstract: A system for monitoring parameters related to a product in a storage tank is provided. The system includes a monitor operably coupled to the storage tank, an internet protocol (IP) enabled electronic device, and an internet protocol enabled controller. The controller is in communication with the monitor and the electronic device. The controller and the electronic device communicate through an internet regarding information observed by the monitor.

Abstract: A wireless tank level monitoring system is provided. The system includes a transmitter that is located in close proximity to the storage tank. The transmitter is coupled to a remote-ready tank level gauge, which provides a ratio-metric voltage output proportional to the liquid volume inside the tank. The transmitter periodically monitors the output from the level gauge and transmits the information to a base station located remotely from the storage tank. The base station displays the tank level numerically in percent full, graphically with a bar chart, or both. A conspicuous visual indication is provided by the base station when the tank level drops below a predetermined set point. In battery powered applications, the base station also reads and provides a visual indication of a low battery condition for both the transmitter and base station.

Abstract: A liquid level measuring apparatus is provided, which includes an input circuit configured to receive electrical signals from level sensors configured to provide an electrical signal proportional to a liquid level in a tank portion. The input circuit provides a single output signal proportional to the combined liquid level in one or more liquid storage vessel portions. The apparatus may further include or be connected to a transmitter such as a wireless transmitting device.

Abstract: A liquid level measuring apparatus is provided, which includes an input circuit configured to receive electrical signals from level sensors configured to provide an electrical signal proportional to a liquid level in a tank portion. The input circuit provides a single output signal proportional to the combined liquid level in one or more liquid storage vessel portions. The apparatus may further include or be connected to a transmitter such as a wireless transmitting device.

Abstract: A capacitance measurement circuit and probe includes a drive circuit couplable to a constant-current source, a threshold detector, a probe capacitor, and a reference capacitor. The circuit includes a plurality of switches being actuatable to alternately couple the current source to the probe capacitor and to the reference capacitor. The drive circuit is configured to alternately generate a signal of linear ramp waveform having a slope that is proportional to the magnitude of capacitance of the probe capacitor and of the reference capacitor. The voltage differential between the probe capacitor and reference capacitor are actively nulled to nominally eliminate a parasitic capacitance therebetween.

Abstract: A capacitance measurement circuit and probe includes a drive circuit couplable to a constant-current source, a threshold detector, a probe capacitor, and a reference capacitor. The circuit includes a plurality of switches being actuatable to alternately couple the current source to the probe capacitor and to the reference capacitor. The drive circuit is configured to alternately generate a signal of linear ramp waveform having a slope that is proportional to the magnitude of capacitance of the probe capacitor and of the reference capacitor. The voltage differential between the probe capacitor and reference capacitor are actively nulled to nominally eliminate a parasitic capacitance therebetween.

Abstract: A fluid sensor (100) senses a level of fluid (20) in a receptacle (10). The fluid sensor comprises a detector assembly (200) for detecting fluid and comprises sensor circuitry. The detector assembly comprises a detector body (201) comprising an electrically insulative material and defining first and second surfaces (210, 220) in a predetermined spaced relation. The detector body defines a space (250) between the first and second surfaces and defines a port (255, 257) for allowing fluid to pass in the space between the first and second surfaces. The detector assembly also comprises first and second conductive layers (212, 222) deposited over at least a portion of the first and second surfaces of the detector body, respectively. The sensor circuitry is conductively coupled to at least one of the first and second conductive layers for generating an electrical signal based on whether fluid is present in the space between the first and second surfaces.

Abstract: A level detector circuit for detecting a level of immersion of an elongated probe within a liquid. The level detection circuit includes a first set of transistors. One of these transistors charges an elongated probe and a second charges a capacitor. A reference current source provides a reference current based on the charging current provided to the elongated probe by the first transistor and an additional transistor which also charges the probe at a rate such that the voltage on the capacitor and the probe are maintained the same. A monitoring circuit develops an analog level signal based on the current provided by the reference current source. This analog level signal is converted by the combination of an analog to digital circuit and a microprocessor for providing a pulse frequency modulated communications signal corresponding to the analog level signal which in turn is related to the length of the probe immersed within the liquid.

Abstract: A test circuit for testing operation of a liquid level detector. The liquid level detector includes a probe that is placed at a test site. A control circuit monitors changes in capacitance of the probe due to changes in the liquid level at the test site. A test switch grounds an input to the probe which and causes the control circuit to sense an alarm condition. If the detector does not activate an alarm when the test switch is actuated, the detector is not properly functioning and repair or replacement of the level detector is needed.