APPARATUS USING A FEEDBACK NETWORK TO MEASURE FLUID PRESSURES

摘要

An apparatus for measuring the pressure of a liquid column (36) enclosed within a pressurized tank or cell (37), and for deriving the height and/or density of the liquid column based on the measured pressure. The apparatus includes a first pressure sensor (38) for differentially measuring the pressure within the cell relative to a reference pressure at a first height (H1), and further includes a second pressure sensor (39) for differentially measuring the pressure within the cell relative to a reference pressure at a second height (H2). A feed back network (48) is operative to match the reference pressure to the pressure within the cell at one of the first and second heights. The feedback network ensures that the sensor detecting the one region is maintained at a zero or null differential pressure condition, enabling the use of a small dynamic range sensor.