| 摘要 |
PURPOSE:To make both the checking of backward flow during forward flowing and the drainage for freeze proofing possible by a structure wherein a reversible non-return mechanism is arranged inside the switching flow passage of a spherical valve body and the direction of said non-return valve is rendered to be freely changed-over from and to forward flow direction to and from reverse flow direction. CONSTITUTION:If the backward flow of the fluid such as waste water occurs due to the abrupt failure of water supply, the fluid applies its pressure to the non-return valve 12 of the spherical valve body 8, resulting in pressing the non-return valve 12 against a valve seat 10 so that a valve port 11 is tightly closed in order to check the backward flow of the fluid. On the other hand, in case that the drainage is intended to perform at a cold district, a lever 24 is displaced and the spherical valve body 8 linking through a handle shaft 22 with the lever 24 is turned 180 deg., resulting in stopping the reversible non-return mechanism A, which had been faced toward an outlet 5 side theretofore, at the position facing toward an inlet 4 side. After the switching operation as mentioned above, the remaining water in the secondary pressure side reaches by flowing reversely in the direction described above through the passage of the fluid for its circulating stage to reach the switching flow passage 9 of the spherical valve body 8 and then discharged outside by opening water taps and the like while a main line stop valve being kept closed. |
