Patent ID: 8210493

Claim:
A water hammerless valve comprising: a pneumatically-operated valve comprising a valve disc for opening and closing a fluid channel by moving upward and downward through operation of a pneumatic actuator, and a limiting mechanism for interfering with upward movement of the valve disc when the water hammer occurs, wherein the limiting mechanism comprises (1) a stepping motor fixed on the top of the pneumatic actuator and including a rotation shaft extending downwardly, (2) a vertical movement component connected to the rotation shaft of the stepping motor for moving upward when the rotation shaft rotates in one rotating direction, and for moving downward when the rotation shaft rotates in the opposite rotating direction, (3) a lower detecting component for detecting the fact that the vertical movement component contacts the upper end of a stem connected to the valve disc when the lower detecting component moves downward, (4) a control device (a) for rotating the stepping motor in one direction when the control device starts air supply to the pneumatic actuator, (b) for rotating the stepping motor in the opposite direction when the control device stops air supply, and (c) for transmitting a stop signal to the stepping motor when the lower end of the lower detecting component detects the fact.