초록 ▼

This invention relates to apparatus for determining the amount of liquid in a tank by measuring the pressure at the bottom and at a height above the bottom of the tank, and provides apparatus for compensating for apparent volume measurement variations caused by expansion and contraction of the tank

This invention relates to apparatus for determining the amount of liquid in a tank by measuring the pressure at the bottom and at a height above the bottom of the tank, and provides apparatus for compensating for apparent volume measurement variations caused by expansion and contraction of the tank and liquid with variation in temperature. A tube which expands in length at an exactly compensating rate varies the height of the second pressure sensor relative to the first. A further embodiment is a pneumatic system which avoids the necessity to immerse the pressure sensor, and utilizes an inexpensive single differential pressure transducer instead of two, and which cancels out the effect of any changes in zero setting of the transducer, changes in sensitivity of the transducer, or changes in atmospheric pressure.

대표청구항 ▼

Apparatus for determining the volume of liquid relative to a known reference temperature in a tank comprising: (a) first means for determining the pressure of the liquid at the bottom of the tank, (b) second means for determining the pressure of the liquid at a height above the bottom of the tank, (

Apparatus for determining the volume of liquid relative to a known reference temperature in a tank comprising: (a) first means for determining the pressure of the liquid at the bottom of the tank, (b) second means for determining the pressure of the liquid at a height above the bottom of the tank, (c) a first tube closed at one end, and closed at the other end by an expansion means, the tube being formed of material having a similar temperature coefficient of expansion as that of the tank, and being filled with a liquid having a temperature coefficient of expansion similar to that of the liquid in the tank, whereby the expansion means moves outwardly or inwardly axially of the tube with expansion or contraction of the tube and liquid in the tube, (d) the first and second means being located such that upon immersion into the tank with said second means vertically above the first means, they are separated by the ends of the tube, their separation defining said height, and whereby with expansion of the expansion means, their separation changes, (e) the expansion means being comprised of a bellows, individual first and second elongated tubes, means for disposing one end of one elongated tube at the end of said first tube, means for disposing one end of the other elongated tube at the end of the bellows opposite said first tube, and a third elongated tube, means for disposing one end of the third elongated tube in the atmosphere just above the surface of the liquid, a source of compressed gas, means for applying the compressed gas to the first and second elongated tubes at pressures just balancing the liquid pressures at the bottom of the tank and at said height respectively, a differential pressure transducer, means for connecting inputs to the transducer to the third and first elongated tubes respectively to obtain a measure of the liquid pressure at the bottom of the tank relative to atmospheric pressure, means for connecting inputs to the transducer to the third and second elongated tubes respectively to obtain a measure of the liquid pressure at said height relative to atmospheric pressure, and means for providing an output signal from the transducer corresponding to said pressures, relative to atmospheric, whereby the pressure differential of the liquid at the locations of said first and second means can be determined as a parameter for obtaining an indication of the volume of liquid in the tank independently of the effects of expansion of the liquid and of the tank due to their temperature changes.