GB775161A - Improvements in centrifugal pump installations - Google Patents

Abstract

775,161. Centrifugal pumps. LEDUC, R. May 17, 1955 [May 17, 1954], No. 14171/55. Class 110 (1). In a centrifugal fuel pump for an aircraft, the suction conduit includes an injector fed by liquid bled from the delivery, and a vessel of relatively large capacity is provided between the injector and the pump inlet and above the level of the pump and injector, the upper part of the vessel constituting a collector space for vapour and gases, the space being vented, preferably through a non-return valve. A centrifugal pump 2 draws liquid from a tank 6 by way of a pipe 5 and an air separator 7 and discharges it to a delivery pipe 1a. Separated air is returned to the tank 6 by way of a non- return valve 11 and pipe 9. To avoid evolution of gas and vapour at the pump inlet 12, the inlet is pressurized by means of an injector in the pipe 5, comprising a venturi 4b and a nozzle 4a fed with liquid bled from the pump discharge through a pipe 10. Any gas or vapour present at the inlet 12 is sucked through a pipe 19 and non-return valve 24 back to the tank 6 by means of an injector 20, 21 fed with liquid bled from the pump discharge through a pipe 22. Priming is effected by a positive-displacement pump, such as a gear pump 23, connected between the bottom of tank 6 and the pump inlet 12. In some installations, such as fuel systems for ram-jet propelled aircraft, it may be desirable to cut off the supply to the pump 2 when the liquid in tank 6 reaches a low level, and this is ensured by arranging that, as shown, the pipe 5 does not extend to the bottom of the tank. The pump 23 delivers enough liquid to the pump 2 to prevent the latter from seizing under these circumstances. The pump 2 may be of the double-inlet type, with separate members 19, 20, 21, 22, 24 for each inlet.