| 摘要 |
PURPOSE:To perform stable constant pressure control by performing such control that the pressure characteristic due to the flow rate change of a pressure control valve is not affected by the flow rate change. CONSTITUTION:Just after a pump is started, the water which comes from an inflow port water passage 1 to a piston end part chamber 6c is balanced to generate a back pressure at the rear of a piston 14, and a valve member 5 is opened to its full width because it is higher than the pressure on the side of an outflow port water passage 2, and water is supplied to a water supply piping through a throttle valve 10. The degree of opening of the valve 10 is increased for a high flow rate and is reduced for a row flow rate to make the pressure of the water passage 2 approximately constant. If a water cock is closed to stop the use of water, the valve 10 is closed because the pressure in the water passage 2 rises, and water pushes up a check valve 61 of a check valve 60 and and flows to the side of the water passage 2. When the pressure of a water supply piping system reaches a pump stop pressure thereafter, the pump is stopped, and the valve 60 is closed. Thus, correct constant pressure control is performed.
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