GB570212A - Improvements in or relating to self-priming centrifugal pumps - Google Patents

Abstract

570,212. Centrifugal pumps. LaBOUR, H. E. Jan. 7, 1943, No. 341. Convention date, Feb. 25, 1942. [Class 110 (i)] [Also in Group XXI] Relates to a construction and arrangement of self-priming centrifugal pump suitable for use in a mobile type of fire fighting equipiment which may be coupled to an automobile for transport, and is of the type which employs a charge of liquid which is maintained in the pump, and in which air from the intake is entrained and discharged through liquid in a separator or discharge chamber to evacuate the suction pipe and fill the pump with water. The pump preferably employs a straight bladed impeller and works on the recirculating principle with a hydraulic balanced throat of the style described in Specifications 472,661, 472,662, 511,304 and 536,359. The pump is shown in Figs. 2, 4, and comprises a substantially cylindrical barrel portion 45, forming the lower part of main pump casing 21 and having a central inlet opening 44 to the impeller chamber 28 and constituting an intake trap. The upper part 51 of the main pump casing 21 constitutes a separator 47. The impeller chamber 28 has main and auxiliary peripheral discharge passages 52, 54, respectively, in approximately the same plane, leading to the separator 51, the passage 52 opening substantially tangentially from the impeller chamber along a part of the separator 47, which is so shaped that, during priming, the discharge stream of the mixture of air and liquid, by being caused to follow the interior of the separator 47 along an arched pathway against a head member thereof is thrown out of register with the auxiliary discharge passage 54 to free the mixture of the entrained gas such as air. Gas freed in the separator 51 passes to an offset portion 57 leading to a discharge elbow fitting 60 connected by a coupling 65 to a Y-shaped valved twin hose connection 66. The gas may be allowed to escape for example through a copper tube 61 of small bore. A priming cock 62 for the pump is provided and also a strainer 73 in the pump intake at 69. The chamber 45 is designed to retain part of the liquid being pumped when the pump stops. A bell bracket 12 of the form shown in Fig. 2 rigidly connects the crank case of the driving engine 4 to the main pump casing 21 one wall 22 forming part of the impeller chamber 28. The impeller shaft is rigidly coupled to the engine crank shaft 16. The Specification as open to inspection under Sect. 91 comprises also a construction of chassis and arrangement of hose and disposition of accessories such as hose to ensure a low centre of gravity for the motor pump unit. This subject-matter does not appear in the Specification as accepted.