| 摘要 |
PROBLEM TO BE SOLVED: To prevent a water hummer in relation to a motor-operated valve used for a fire extinguishing facility and its controlling method. SOLUTION: The motor-operated ball valve 2 has a secondary side having a nozzle 5 disposed in an empty water feed pipe, and controlled by a control means 8. The control means 8 initially partially opens the valve to provide a flow speed for preventing the water hummer, and fully opens the motor- operated ball valve 2 after running water reaches the nozzle 5. The other control means 8 initially fully opens the motor-operated valve ball 2 to make water flow for a certain time, and partially opens the motor-operated ball valve 2 slightly before the water reaches the nozzle 5, thereby preventing the water hummer.
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