| 摘要 |
[PROBLEMS] A water hammer-less valve in which a pneumatically operated valve automatically prevents a stem from rising when water hammer occurs, thereby opening of a flow path is limited. [MEANS FOR SOLVING PROBLEMS] The water hammer-less valve has the pneumatically operated valve in which a flow path is opened and closed by a valve body moving up and down by operation of a pneumatic actuator, and also has a limitation mechanism for limiting the rise of the valve body when water hammer occurs. The limitation mechanism has a stepping motor whose shaft is fixed to the upper part of the actuator; a vertically moving member connected to the rotating shaft, rising as the rotating shaft rotates in one direction, and lowering as the rotating shaft rotates in the opposite direction; a lower end detection member for detecting the fact that the vertically movable member descends to be in contact with the upper end of the stem; and a control device for rotating the stepping motor in one direction when supply of air to the actuator is started, rotating the stepping motor in the reverse direction when the air supply is stopped, and sends a stop signal to the stepping motor when detection is made by the lower end detection section.
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