GB755429A - Pumps - Google Patents

Abstract

755,429. Centrifugal and axial-flow pumps. PULSOMETER ENGINEERING CO., Ltd. Jan. 28, 1955 [Jan. 28, 1954], No. 2590/54. Class 110(1) [Also in Group XXVII] A pump for use with volatile or gas-containing liquids comprises at least two firststage impellers which discharge into a common chamber, one of these impellers being so disposed at or near the top of the common chamber that vapours can escape through it from the common chamber, and a second-stage impeller which receives liquid from a lower level in the common chamber. The second-stage impeller and the impeller or impellers of any subsequent stages may be mounted on the same shaft as at least one of the first-stage impellers. Separate driving motors may be provided. Fig. 1 shows a fuel pump mounted in an aircraft fuel tank 10 and comprising firststage impellers 12, 13 and a second-stage impeller 14 mounted on a common shaft 16 driven by an electric motor 17. Under normal conditions, impeller 13 is submerged while impeller 12 is generally above the fuel level. Any gas or vapour bubbles rise to the top of the common chamber 18 and escape through the impeller 12. Under negative gravity conditions, the fuel gravitates to the top of the tank 10 and the functions of the impellers 12 and 13 are interchanged. Vapour separators may be provided on or in front ef the first-stage impellers. In a modification, Fig. 3, a further first-stage impeller 21 is mounted on a shaft 22 driven through gearing 23 from the motor 17a, to permit operation under the zero gravity condition shown. Fig. 4 shows a pump mounted by means of a flange 26 in an opening in the bottom 19b of an aircraft fuel tank. The first-stage impellers 12b, 13b and the second-stage impeller 14b are driven by a hydraulic or electric motor' or an air turbine 17b, preferably through flexible couplings 37, 38, the cable or pipe 30 supplying the motor or turbine being led in through the flange 26. Each impeller 12b, 13b has a vapour discharge passage 27 at its periphery. Inlet strainers 28 are provided. The fuel passes from the first stages to the second stage by way of a chamber 18b and is discharged from the second stage through a delivery pipe 15b. The motor may be mounted above the pump or below the flange 26; speedreduction or other gearing may be provided.