GB780699A - Improvements in and relating to pumps for the conveying of gases - Google Patents

Abstract

780,699. Gas pumps. VOGT, A. Feb.29, 1956 [March 5, 1955], No. 6291/56. Class 8(1). In a mechanically operated gas pump having a chamber with means for periodically raising and lowering the level of a liquid contained therein, permanent communication is provided between said chamber and the discharge side of the pump so that during the suction stroke of the pump a vacuum is created in the chamber by the lowering of the liquid level, gas is introduced through an inlet valve and liquid flows slowly from the discharge side into the chamber but does not fill same, and during the discharge stroke the raising of the liquid level expels the gas and part of the liquid from said chamber. The means for raising and lowering the liquid level may comprise a piston or, as in Fig. 1b, a diaphragm 5 clamped between plates 9 connected to a shock absorbing fitting 8 reciprocated by a motor. The pump casing 1 encloses a lining 4 of synthetic material shaped to form the main pump chamber, a space 22, and discharge pipe 24, with a bore 23 and aperture 21 between them. A pipe 12 from the gas supply is normally closed by an inlet valve 15 being held on its seat 18 by a tension spring 16, the valve being opened when a dog 19 carried by upper plate 9 engages a dog plate 20 on the valve. Initially mercury in exhaust pipe 24 fills space 22 and the pump chamber beneath. On the downward stroke of the diaphragm 5 a vacuum is created in the pump chamber. The small aperture 21 allows mercury to flow from space 22 into the chamber but not fast enough to fill the vacuum. The latter is filled with gas from inlet 12 when dog 19 opens the valve 15. Since bore 23 is smaller than aperture 21, a vacuum is created in space 22 as mercury cannot enter through bore 23 so quickly as it flows out of aperture 21. On the upstroke of the diaphragm the valve 15 is closed, gas is compressed in the chamber and is expelled therefrom together with some of the mercury. The gas in space 22 is compressed and is then expelled with some of the mercury into the discharge pipe 24. Hence the action of a two-stage pump is attained. In the embodiment of Fig. 2, the effect of the aperture 21 is obtained by a spring-loaded valve 52 and a passageway 67 which may be in the valve or the surrounding member ; the space 22 is replaced by a space enclosed by an elastic hose member 57 ; and the bore 23 is replaced by a bore 68 in a valve body 59.