| 摘要 |
1375927 Centrifugal pumps GORMANRUPP CO 22 Feb 1972 [22 Feb 1971] 8171/72 Heading F1C [Also in Division F2] During priming of a pump 202, a mixture of liquid and air is vented from the discharge side of the pump via a pipe 226, a vortex chamber 224 and a vent pipe 228, the pipe 226 being disposed tangentially to create a vortex in the chamber. On completion of priming, the resultant increased vortical flow of liquid through the chamber 224 produces an increased pressure differential on a vent valve 234, causing it to close against the action of a spring 242. Liquid now flows through the pump discharge pipe 206, thereby opening a non-return valve 214 against the action of a spring 220. Arm 218 of the non-return valve then operates a micro-switch 260 to energize a solenoid 252 which assists in holding the vent valve 234 in the closed position. The micro-switch 260 may be replaced by a mercury switch attached to the arm 218 or a pressure-actuated switch sensitive to the pump discharge pressure in which a moving switch contact is formed by the needle of a Bourdon tube pressure gauge. |
