| 摘要 |
PURPOSE:To prevent a siphon phenomenon from generating, by a method wherein a downward liquid flow and an upward liquid flow are checked in intermediate parts of branch pipes. CONSTITUTION:Opening pressures of checking mechanisms 6, 7 of a valve V are respectively set to be not lower than 1kg/cm<2> and not higher than 0.5kg/cm<2>. When the distance from the pipe 2 at a height of 3m to the valve V is 2.5m and the distance from the valve V to the distributing valve is 0.5m, the checking mechanism 6 blocks the downward liquid flow by a closing torque of about 0.7kg/cm<2> (1-0.25-0.05) when the pump is stopped. When a cause of leakage of the liquid is generated at a lower part of a pumping-up (main) pipe, the negative pressure exerted on the back flow is considered to be not higher than -0.1kg/cm<2>, so that when the negative pressure (siphon suction) exerted on the checking mechanism 7 is 0.1kg/cm<2>, the upward liquid flow is blocked by a closing torque of 0.4kg/cm<2> (0.5-0.1), whereby air is prevented from being sucked into the piping system. |
