| 摘要 |
PROBLEM TO BE SOLVED: To provide a backflow preventing device securely capable of achieving separation and draining backflow of sewage. SOLUTION: An inflow passage 14 and a main introducing passage 44 are communicated with each other through a pilot solenoid valve 48. The main introducing passage 44, a main valve chest 93, and a discharge passage 15 are disposed along a straight line. A first check valve 67 is provided on an inlet of the main valve chest 93. A second check valve 68 is provided on an outlet of it. A separation back pressure chamber 91 of a separation valve 89 and a drain back pressure chamber 101 of a drain valve 99 are communicated with the inflow passage 14 through a primary pressure communication passage 107. An air introducing passage 21 is communicated with the main valve chest 93 through the separation valve 89. A discharge passage 15 is communicated with a drain passage 105 through the drain valve 99. The separation valve 89 and the drain valve 99 maintain closed states as primary pressure on the side of the inflow passage 14 is added to the separation back pressure chamber 91 and the drain back pressure chamber 101, and are opened when the primary pressure becomes negative. COPYRIGHT: (C)2004,JPO&NCIPI
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