PURPOSE: To secure a pumping plant that eliminates any trouble due to jumping at the time of starting by installing an energizing means in response to pump discharge pressure, in a closing pressure setting means of a bypass valve installed in a bypass passage for a pump.
CONSTITUTION: When a pump 3 is rotated by a motor, a solution is discharged out of an outflow port O by way of a check valve 1, a strainer chamber 2 at the inflow side, the pump 3, a gas-liquid separator 4, a chamber at the outflow side and a control valve 30 from an inflow port 1. In addition, a part of the solution out of a discharge port 3b is bypassed to a suction port 3a by way of a bypass valve 20. In this case, a valve element 21 of this bypass valve 20 is supported by a casing C free of slide motion at the projecting end 22, and it is closed by a spring 25 interposed in a gap with a cylinder 24 housed in a piston chamber 23. Then, a shutoff pressure setting means is constituted of the member 22, and an energizing means is composed of the members 23, 24 and a solution passage 11a.
SAKUMA KUNIO
OTAKI TSUTOMU
