| 摘要 |
PROBLEM TO BE SOLVED: To execute a pressure resistance test in a state that a decompression valve is mounted on piping without using any by-pass pipe or the like. SOLUTION: A pressure detecting channel 38 through which a pressure detecting chamber 7 is communicated with a second pressure chamber 3 is provided with a continuously formed opening route 39 whose one edge is opened to the outside and which is equipped with a communicating port 40 to a primary pressure chamber 2. At the time of executing a pressure resistance test, a first channel port M1 facing to the pressure detecting chamber 7 is closed in the pressure detecting channel 38, and the opening route 39 is stopped by a by-pass constituting tap 42 communicating a second channel port M2 facing to the secondary pressure chamber 3 through an internally penetrating straight route 44 with the communicating port 40, and the pressure detecting channel 39 is put into an incommunicatable state so that the decompressing function can not act, and that the primary side and the secondary side can be put into a water flow enabling state. A by-pass X of the primary side and secondary side is constituted of the straight route 44, and even when the decompression valve is closed since a high pressure acts on the primary side at the time of the pressure resistance test, the water flow can be maintained through the by-pass X. After the pressure resistance test, the opening channel 39 is closed by the depressing function tap 43 for closing the communicating port 40, and only the pressure detecting chamber 7 and the secondary pressure chamber 3 are communicated with each other so that the decompressing function can act.
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