Abstract: A hydraulic liquid pressure sensor for use in a gas operated pressure sensor system includes a sensor body with a generally circular membrane resting surface, an inlet connected to a peripheral portion of the surface and an outlet opening from a central location on the surface. A flexible membrane is positioned adjacent to the resting surface and in flush contact therewith when not in use. The flexible membrane is secured and sealed around the periphery of the circular membrane resting surface. The inlet includes an annular groove in the pressure sensor body and spaced around substantially outward of the outlet opening. The inlet also includes an additional groove in the sensor body opening to the resting surface, connected to the annular inlet groove and extending inwardly therefrom.

Abstract: A system for measuring the density of a hydrostatic liquid in a container includes a pair of serially connected pressure sensors mounted in the liquid, a constant volume gas flow source connected to an inlet of one pressure sensor, a second pressure sensor connected to the outlet of the first pressure sensor, and a vent is connected between the second pressure sensor outlet and the atmosphere. A gauge or pressure transducer in the gas conduit from the source to the first pressure sensor provides pressure measurements that can be used to determine the level of liquid in the container and a differential pressure transducer across the first pressure sensor can be used to determine density of the liquid. Exhaust gas from the pressure sensors is passed to the atmosphere through a pressure buffering device in one construction of the system. The pressure sensors each have a rigid body with a generally circular resting surface over which a flexible diaphragm member is positioned.