Liquid pressure and level sensor systems and sensors, methods, and applications therefor

A sensor system having a liquid level sensor that comprises:

• a tube having an open first end and a closed second end that is closed with a gas-tight sealing member containing a gas pressure sensing device adapted to sense a pressure of a gas within the tube, the first end being open to enable a liquid to enter the tube to define a chamber in which the gas is trapped and prevents contact between the liquid and the gas pressure sensing device;
• electrical connections to the gas pressure sensing device that are routed through the gas-tight sealing member and comprise at least one set of cables;
• and
• electronic means for determining a level of the liquid outside the tube based on the pressure of the gas trapped within the tube sensed by the gas pressure sensing device;
• and
• at least one of an ultrasound range finder as means for directly measuring a height of the gas trapped within the tube and a liquid presence sensor that directly detects the level of the liquid outside the tube.

A sensor system having a liquid level sensor comprising:

• a tube having an open first end and a closed second end that is closed with a gas-tight sealing member containing a gas pressure sensing device adapted to sense a pressure of a gas within the tube, the first end being open to enable a liquid to enter the tube to define a chamber in which the gas is trapped and prevents contact between the liquid and the gas pressure sensing device;
• electrical connections to the gas pressure sensing device that are routed through the gas-tight sealing member and comprise at least one set of cables;
• and
• electronic means for determining a level of the liquid outside the tube based on the pressure of the gas trapped within the tube sensed by the gas pressure sensing device;
• wherein the gas pressure sensing device is a first gas pressure sensing device of the sensor system, and the sensor system further comprises a second gas pressure sensing device;
• wherein the liquid level sensor comprises the first and second gas pressure sensing devices, the tube of the liquid level sensor is a first tube thereof, and the liquid level sensor comprises a second tube that has a closed end containing the second gas pressure sensing device, the second tube having an open end that projects outside the first end of the first tube so that the second gas pressure sensing device is adapted to sense a different pressure than the pressure sensed by the first gas pressure sensing device to provide a self-calibration and correction schemes that includes calculating mass density of the liquid.