| 摘要 |
PROBLEM TO BE SOLVED: To provide a backflow prevention device of pressure reducing type having small loss of pressure. SOLUTION: A solenoid device 35 pulling up a valve element 19 operating against a spring 31 as an energizing means is provided in a first check valve 11 provided between a primary side flow 5 and an intermediate chamber 9. A sensor 69, detecting the opening of a valve element 79 and a metal piece 60, is provided in a second check valve 45 which is provided between the intermediate chamber and a second flow path 7. When the second check valve reaches a prescribed opening in the beginning of water feed start, the solenoid device is operated by a signal from the sensor, the first check valve is placed in a fully opened condition. The valve element 79 of a relief valve 171 is energized in the closing direction by a spring 190. When water is discharged, the solenoid device is operated, the relief valve is opened. Here, the spring of the first check valve can be made small force.
|
