Patent ID: 7278437

Claim:
A water hammerless closing device comprising: (a) an actuator operated-type valve installed in a fluid passage; (b) an electro-pneumatic conversion device connected to supply a 2-step actuator operating pressure Pa to the actuator operated type valve; (c) a vibration sensor removably secured to the fluid passage on an upstream side of the actuator operated-type valve; and (d) a tuning box connected to receive input including a vibration detection signal Pr detected by the vibration sensor, and the tuning box outputs a control signal Sc to the electro-pneumatic conversion device to control a level of a step operating pressure Ps′ of the 2-step actuator operating pressure Pa so the electro-pneumatic conversion device outputs, by adjusting the control signal Sc, the 2-step actuator operating pressure Pa with the step operating pressure Ps′ permitted to bringing the vibration detection signal Pr to near zero.