| 摘要 |
594,570. Priming centrifugal pumps. WAYNE PUMP CO. April 20, 1945, No. 9986. Convention date, June 23, 1944. [Class 110 (i)] A centrifugal pump 262, Fig. 5, is primed by a continuously running piston pump 390 which draws air from a float chamber 326 forming an extension of the impeller inlet chamber 256. The float valve 348 closes the connection to the piston pump when the liquid level is high enough. A second float valve becomes operative if the float valve 348 fails and liquid enters a chamber 354. When either of these valves closes, the piston pump produces an increased vacuum on its suction side and this is used to open a valve in the delivery of the centrifugal pump. The delivery valve is loaded by a weight and is connected to a piston subjected on its upper side to the vacuum in the suction chamber of the piston pump and on its underside to the impeller delivery pressure. In another arrangement of valves the pump impeller 110, Fig. 2, receives liquid from an inlet 98 through a float chamber 102 and delivers through passage 140 controlled -by a piston valve. 142. The crank-case 20 of the piston pump is connected to'its suction side and to the upper side of a diaphragm 172. The latter is subjected on its under side to the pressure in the impeller inlet chamber 106. The diaphragm controls a ball-valve 166. The head of the piston valve 142 has an orifice 152. During priming the pressures in the piston pump casing and the impeller inlet 106 are substantially the same and the valve 166 is shut because of the loading spring 168. The orifice 152 keeps the piston valve 142 balanced and the valve is kept shut by the loading spring 154. When liquid, rising in the float chamber, causes the float valve to shut, the continuing operation of the piston pump produces an increased vacuum on its suction side and above the diaphragm 172 sufficient to permit the ballvalve 166 to open. This opens a passage large compared with the orifice 152 and the pressure behind the valve 142 falls, so permitting the impeller delivery pressure to open the valve 142. The eye of the impeller 262, Fig. 5, runs with little clearance within a ring 264 having an inturned flange 266 which directs into the impeller any liquid from the delivery leaking past the ring 264. The float 334 has a flange 332 so that a surge of water assists in lifting the float. A channel 416 provides an easy passage for air to the top of the chamber 326. A passage 412 connects the suction chamber 380 and crank-case 280 of the piston pump and prevents pumping of oil by the piston. The pump shown is intended for dispensing petrol and the shaft 268 is provided with a petrol seal 272 and an oil seal 274. If either fails, the leaking fluid passes down a channel 418. The piston pump has an oil splash ring 394 which serves, in part, as a counterbalance to the piston.
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