초록 ▼

A tank contents gauge is disclosed having two pressure sensors to sense the liquid pressure at two tank positions at known vertical separation, a port to sense the ambient pressure in the tank, and a transducer to which the three pressure readings are transmitted one at a time by a switching mechani

A tank contents gauge is disclosed having two pressure sensors to sense the liquid pressure at two tank positions at known vertical separation, a port to sense the ambient pressure in the tank, and a transducer to which the three pressure readings are transmitted one at a time by a switching mechanism. If the transducer is a differential transducer, its second side is connected to the port to allow (1) comparison of the pressure readings with the ambient pressure reading and (2) determination of transducer offset to adjust the calculations to give accurate readings. The readings are analysed by a data processing system which can provide volume and weight readings by internal look-up calibration tables. The system may also control the switching mechanism. Specific gravity values can be calculated from the pressure readings and the known vertical separation; the values can be stored in the system for use when the tank contents approaches, or falls below, the level of the upper sensor.

대표청구항 ▼

A method of measuring the liquid contents of a tank comprising placing first and second pressure sensors at a known vertical distance apart in said tank, with said second sensor sensing the pressure at a higher level than said first sensor, placing means for taking a pressure reading above the liqui

A method of measuring the liquid contents of a tank comprising placing first and second pressure sensors at a known vertical distance apart in said tank, with said second sensor sensing the pressure at a higher level than said first sensor, placing means for taking a pressure reading above the liquid in said tank, connecting, for each reading of tank contents to measure the liquid contents thereof, each of said first sensor, said second sensor and said means for taking a pressure reading above the liquid in said tank selectively to a single pressure transducer by a switching mechanism to produce electrical signals, transmitting said electrical signals to a data processing system having a memory and having been programmed to compare said electrical signals with a preset pressure value to indicate whether the liquid depth is sufficient for a valid reading at said second sensor, permitting said data processing system to compare said electrical signals with said preset pressure value, and, depending on the result of the comparison, carrying out one of the following operations: (a) if the pressure reading at said second sensor is above said preset pressure value, calculating a specific gravity from the electrical signals and the known vertical separation and storing said specific gravity in the memory of said data processing system as a last calculated specific gravity, and calculating the liquid depth using this specific gravity value; or (b) if the pressure reading at said second sensor is below the preset pressure value, calculating the liquid depth using said last calculated specific gravity value from the memory.