Abstract: Pressure sensing device having a housing (12) with a bottom wall (14) and interior surface (16) and having upstanding edge wall (18) around the periphery of said housing (12). A layer (22) supports a pressure sensing element (30) and its circuitry. A porous gas permeable support layer (40) overlies said pressure sensing element (30) and includes a gas chamber (42) adjacent to the pressure sensing element (30). A gas permeable membrane (50) is supported on said support layer (40). The elements are sealed with respect to the housing as is wire or cable (32) leading from the pressure sensing element (30) to instrumentation remote from the sensing device for readout of measurements by the sensor device (10).

Abstract: Single, self-contained, multiple parameter device (10) and method which includes a probe (12) having a water or liquid exposed sensing compartment (61) wherein a permeable tubular membrane (46) transmits total dissolved gas pressure to a sensor (96) in a waterproof compartment. A temperature sensor (92) measures the temperature of the monitored water. Both of the sensed parameters are converted to electrical signals and routed by cable (14) to a control housing (12) and therein combined and analyzed by appropriate circuitry (100, 102, 104, 106) and with barometric pressure signals processed through a selector switch (106) to be visually read out to a display (110). The instrument (10) allows at least for selective read out and display (110) of total dissolved gas pressure, barometric pressure, temperature, percent saturation and difference between total dissolved gas and barometric pressures.

Abstract: The invention measures the total dissolved gas and fluid vapor pressure in liquids both aqueous and organic. It comprises a hydrostatically isolated gas phase of as low volume as possible isolated from the liquid being measured by a gas-permeable membrane configured to be insensitive to hydrostatic pressure, in this instance in the form of a tube. The gas phase inside the tube communicates with a pressure measuring component which is either, in this instance, a special type of closed manometer, or strain gauge which senses pressure by piezoresistive or capacitive pressure induced change or other pressure measuring means of low or negligible internal volume and compliance, together with a calibration means. The invention is provided with a calibrated scale or electronic readout means for the pressure measuring component.