GB333625A - Improvements in or relating to meters for steam or gas - Google Patents

Abstract

333,625. Soc. Rateau. March 20, 1929, [Convention date]. Tell-tale apparatus.-An electric meter for measuring the flow of steam or gas is actuated by the variations in the intensity of a high frequency alternating current, the variations being produced by a variable impedance modified by the flowing fluid. The impedance, is placed in a circuit in which the current is rendered independent of variations in frequency in the sourcecircuit. Means may be provided to neutralize changes due to variations in the static pressure and temperature of the fluid so that the weight of fluid flowing per unit time may be directly measured. The impedance may be a condenser with one armature a fixed and the other b mounted by means of a pendular system d, d<1> and exposed to the flow of the fluid in a pipe c, Alternating current from a high-frequency source, e.g. a thermionic valve, is supplied to the meter circuit through the windings j, j<1> of the source and meter circuits respectively, a loose coupling being formed between j and j<1> in order that the frequency in the meter circuit may be independent of changes in that of the source circuit. Changes in static pressure of the fluid are neutral ized by a condenser mounted in parallel with the main condenser a, b, with armatures e, f, fixed and movable respectively, the latter being connected through a rod i, pressure gauge h, and tube g with the flowing fluid in the pipe c. Variations in temperature are neutralized either by a resistance m, Fig. 1, in series with the main condenser, or a thermometer n, Fig. 2, acting on a movable armature of a condenser in parallel with the main condenser. In the form illustrated, Fig. 2, the condenser has both armatures e, f, movable, the armatures e moving with variations in static pressure and the armature f with variations in temperature. In a modification, Fig. 3, the condenser a, b is mounted in a branch from the pipe c and actuated by the dynamic pressure which may be amplified by means of an orifice in a thin wall, a nozzle, or a Venturi tube. The pressures in front and rear of an orifice l in a thin wall in the pipe c are transmitted by tubes o, p to chambers q, r separated by a diaphragm s carrying the movable armature b of the condenser. The meter k may be graduated direct in kilograms per hour and the variations in the current may act on a recording or integrating apparatus. The term " high frequency '' is used to mean a frequency of the order of 100,000 cycles per second and over.