Patent GB-939692-A (GB)
Title: Centrifugal pump
Inventor: HILL ROBERT ALLAN
IPC: A62C25/00
Filed: 1960-08-15
Abstract: 939,692. Centrifugal pumps; gear pumps. WATEROUS CO. Aug. 15, 1960, No. 28237/60. Classes 110 (1) and 110 (2). [Also in Groups XXIX and XXXI] A centrifugal pump for fire-fighting comprises a casing 10, Figs. 1, 2 and 7, formed with intake manifolds 11, 12 for impellers 21, 22 respectively and a single discharge manifold 13. The manifolds are generally parallel and disposed in a common horizontal plane located above the horizontal axis 157, Fig. 2, of the impeller shaft. Each manifold is double-ended, the ends being flanged for attachment to manifold extensions 145, 145<SP>1</SP> and 153, 153<SP>1</SP>, by means of which the pump is supported upon bearers 142. The pump is driven from the vehicle engine through a gear-box comprising an input shaft 55, Fig. 7, which can be coupled by means of a clutch 93 either with a shaft 56 which drives the vehicle wheels or with a gear 74 which drives the pump through gears 73, 61. The gear-box and a bearing support 44 are secured to similar mounting rings 42, 43 at opposite ends of the pump casing 10 and may be interchanged with one another to permit the gear-box to be located at the other end of the pump casing. If the distance of the input shaft 55 below the tops of the bearers 142 is required to be less than that shown in Fig. 2, the pump casing 10 can be inverted into the position shown in Fig. 5, with the pump shaft axis 157 above the plane of the manifolds and with the input shaft 55 consequently higher in relation to the bearers 142. The centrifugal pump is primed by a gear pump 102, Fig. 8, which can be driven either from shaft 55 through gears 96, 97 and a clutch 120 or by means of an electric motor 212. To prime the centrifugal pump, a push-button switch is operated to energize the motor 212 and to open a solenoid-actuated valve whereby the suction side of the priming pump 102 is connected to the suction eyes and discharge of the centrifugal pump. When a valve 163 is in the position shown in Fig. 11, the discharge of impeller 21 is connected to the intake manifold 12 of impeller 22, and the centrifugal pump operates as a twostage pump, flap valves 170, 171 closing the unused branches 167, 169 of the intake manifold extensions 145, 145<SP>1</SP>. When the valve 163 is in an alternative position connecting the discharge of impeller 21 to the discharge manifold 13, the flap valves 170, 171 open and the impellers operate in parallel. The valve 163 is actuated by a piston energized by the suction of the priming pump 102. When a normally-off double-throw switch is moved momentarily to one of its two contact-making positions, the motor 212 is energized to drive the priming pump 102 and a solenoid-actuated valve is moved to one of two alternative positions to connect one or other side of the piston to the suction side of the priming pump 102, whereby the valve 163 is moved to the required position. Discharge valves 155, Fig. 1, can be operated manually by means of the handles 156 or by means of electric actuators 271. A relief valve 172, Figs. 1 and 15, is connected between the discharge manifold extension 153<SP>1</SP> and an intake pipe 150<SP>1</SP>. The discharge pressure within the discharge manifold 13 is communicated through a pipe 315 and a valve 314 to the right-hand end of the piston 176 of valve 172 and also to one side of a diaphragm 305. If the discharge pressure becomes excessive, diaphragm 305 moves a valve 306 from its seat 311 against the action of a spring 325, thereby connecting pipe 315 through a throttling restriction around the valve 306 to a pipe 322 leading to the pump intake. The consequent reduction of pressure on the right-hand end of piston 176 allows the discharge pressure acting on its left-hand end to move it into the open position against the action of a spring 179. The discharge pressure at which the valve 172 opens is adjustable by means of a handle 327 which regulates the compression of spring 325.