GB700499A - Improvements in or relating to apparatus for measuring the amount of liquid in a container - Google Patents

Abstract

700,499. Electrically measuring liquid quantity ; electric condensers. LIQUIDOMETER CORPORATION. Jan. 29, 1951 [Jan. 31, 1950], No. 29324/52. Divided out of 700,466. Class 37 A condenser whose capacity varies with the density and dielectric constant of a liquid comprises a float, e.g. a cylinder 21, Fig. 1, in a container 14, the capacitance being determined by the depth to which the float is submerged (i.e. the density of the liquid), and the dielectric constant. The device 12 Fig. 3 is combined with a condenser 2, whose capacity varies with the depth of the liquid, in the circuit of Fig. 3 to measure the weight of a liquid in a tank ; each condenser is in parallel with an inductance, the inductance 78 being equal to the reactance of the condenser 12 when the dielectric constant is unity; and the inductance 74 being equal to the reactance of the condenser 2 when free of liquid ; each condenser and inductance forms one arm of a bridge whose other arms are formed by the half-windings of transformer 50, one of which is shunted by a tapped resistance 60 ; the bridge output is amplified at 84, applied to a phase-sensing circuit 100, 110, to produce a D.C. voltage between 118, 124 whose sense is dependent on the direction of unbalance of the bridge ; this voltage is applied to valves 122, 128 whose cathodes are fed with A.C. from transformer 136 so that the output in transformer 146 is A.C. of phase dependent on the direction of unbalance of the bridge ; this is applied to a winding 152 of motor 70 which adjusts the tap 68 on resistance 60 to balance the bridge and actuate an indicator 158. It is shown in the Specification that the position of the contact 68 at balance is independent of the dielectric constant of the liquid but is a direct function of the density of the liquid and its height, so that the indicator 158 is in terms of weight of liquid. Specification 700,466 is referred to.