GB758873A - Improvements in or relating to fluid operated measuring or testing device - Google Patents

Abstract

758,873. Measuring leakage; pressure gauges. CLANG, Ltd., and EVENDEN, R. S. May 11, 1955 [May 11, 1954], No. 13694/54. Class 106 (2). [Also in Group XXIX] A fluid-operated measuring device comprises indicating means which includes an annular tubular ring 14, Fig. 2, in which a fluid, e.g. mercury, is adapted to travel to give an indication relatively to a clock dial 15 mounted concentrically with the ring. As applied to measuring leakage the article 24 to be tested is mounted in an airtight manner in the removable cover 21 of a sealed chamber 16. A pipe 23 leading from the chamber 16 can be put into communication with either end of the ring 14 by means of three-way cocks 19, 20. The other end of the ring 14 can be connected by the same cocks to a pipe 13 leading to a pressure gauge 5, Fig. 1, and thence to a reservoir to which air can be admitted under pressure from a pump 3. Straight through cocks 7, 8, 9 are also provided for connecting various parts of the instrument including a standard volumetric reference 10. In operation air is pumped into the reservoir 4 and chamber 16 to any desired pressure with the ring 14 not in circuit, air is then slowly admitted to the ring 14 from the reservoir side to centralize the mercury 25 either at end A or end B and the chamber 16 is then placed in communication with the ring so that as air leaks from the chamber through the object 24 being tested the mercury moves round the ring at a rate which can be measured by the clock-hand 29. Preferably the total volume of the ring is 1 cc. and the mercury occupies the space of one scale divisions, i.e. one sixtieth cc. A 70 degree overlap is preferably provided between the ends A, B of the ring 14. By connecting one pressure on the reservoir side and a second on the chamber side of the ring 14, the instrument may be used to measure the rate of change of the two pressures relatively to each other.