| 摘要 |
PURPOSE:To execute effectively drainage and to restore a draining function within a short period by restarting water supply even if a residual water position is generated in a unit body by interconnecting between an inflow port and a pressure changing room and between the pressure changing room and a slave valve piping port with through holes having sufficient large apertures. CONSTITUTION:At the time of freezing preventing operation, water supply to a water feeding pipeline 2 is stopped and residual water on the outlet pipeline 4 side of the body 1 is drained through a drain valve 27. At the drainage of residual water in the pressure changing room 10 and the slave valve piping 30, drain valve bodies 20, 20a are lifted upward through valve rods 19, 19a and through holes 11, 13 are opened by lifting operation levers 25, 25a in the drain units 14, 15, and since the apertures of the through holes 11, 13 are respectively set up to sufficiently large values prevented from closing due to the surface tension of water, the residual water in the slave valve pipeline 30 is made flow into the pressure changing room 10 through the through hole 13 and the residual water in the pressure changing room 10 is reached to the inflow port through the through hole 11 and smoothly drained to the outside by a drain valve 28 inserted into a water feeding pipeline 2.
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