GB745867A - Improvements in or relating to measuring system - Google Patents

Abstract

745,867. Electric measurements. LIQUIDOMETER CORPORATION. Nov. 26, 1953 [Dec. 5, 1952], No. 32837/53. Class 37. Apparatus of the type described in Specification 695,074 wherein the weight of liquid in a tank is determined by modifying the measured volume of liquid in accordance with the density on the basis of a fixed relationship between density-and dielectric constant, is characterized by the addition of further calibrating potentiometers to enable the measuring device to be used with different types and sizes of tanks. The electrical circuit (Fig. 1) comprises a number of A.C. fed potentiometers 48, 42, 30, respectively feeding the measuring capacitor C52, a parallel combination of a fixed capacitor C56 and a reference capacitor C58 completely immersed in the liquid being gauged, and a fixed capacitor C34, the other side of each capacitor being connected to a common point 36, whose voltage is fed to an amplifier 62 to drive a 2-phase motor 66 coupled to the slider 54 of potentiometer 42 to eliminate the voltage at 36, whereupon the balance position of the slider 54 is indicative of the weight of liquid gauged by capacitor C52, and is shown on a counter type indicator 74 attached to motor 66. A scale 76 also attached to potentiometer 42 indicates the weight of liquid in the tank as a proportion of the maximum weight of liquid the tank can hold. It is mathematically shown that to accommodate different installations the product of the voltage tapped off from potentiometer 30 and the capacity of 034 must be equal to the product of the voltage tapped off from potentiometer 48 and the capacity of C52 empty. For convenience a scale 82 is associated with potentiometer 48 to facilitate adjustment of this potentiometer for different values of C52 empty. Preliminary adjustments are made on a potentiometer 38 when the tank is empty and a potentiometer 46 when the tank is full. Specification 693,600 also is referred to.