INLET PRESSURE-REDUCING VALVE FOR PUMP

摘要

PROBLEM TO BE SOLVED: To prevent the generation of impossibility of water supply due to closing of an inlet pressure-reducing valve even in the case where the air having a pressure higher than the atmospheric air flows into the inlet pressure-reducing valve provided in a pump of the downstream at the time of starting the water supply in case of connecting plural pumps in series to each other for water supply. SOLUTION: Plural pumps are connected in series to each other, and an inlet pressure reducing valve is provided in an inlet side of a pump provided in the downstream. This inlet pressure-reducing valve is provided with an energizing means 33 for energizing a valve element 26 to a direction for separating from a valve seat 27. When this structure, even in the case where the air pushed by the water to be fed and having a pressure higher than the atmospheric air flows into the inlet pressure-reducing valve at the time of starting water supply, the valve element 26 is seated on the valve seat 27 by the energizing force of the energizing means 33 so as to prevent the closing of the inlet pressure-reducing valve. Furthermore, a pressure receiver area A1 of a second pressure receiver member 28 is formed larger than a passage area A2 of the valve seat 27 so as to be balanced with the energizing force of the energizing means. With this structure, when water supply is cut off during the water supplying work, the inlet pressure-reducing valve is opened so as to prevent the generation of abnormal rise of the pressure inside of the pump.