Patent ID: 7080658

Claim:
A water hammerless closing device comprising: (a) a valve body; (b) an actuator connected to drive the valve body; (c) a vibration sensor removably secured to a pipe passage on an upstream side of the valve body; (d) an electro-pneumatic conversion control device connected to receive input including a valve opening/closing command signal and the electro-pneumatic conversion control device operates to control an actuator operating pressure Pa inputted to the actuator by using a control signal Sc stored, in advance, in a data storage unit of the electro-pneumatic conversion control device; and (e) a computing control device having a comparison computing circuit connected to receive input including a vibration detecting signal Pr originating from the vibration sensor, a step pressure setting signal Ps to be supplied to the actuator, a holding time setting signal Ts for maintaining the step pressure, and an allowable upper limit vibration setting signal Prm and the comparison computing circuit makes a comparison between the vibration detection signal Pr and the allowable upper limit vibration pressure setting signal Prm for modifying the step pressure setting signal Ps so the control signal Sc, composed of the holding time setting signal Ts and the modified step pressure setting signal Ps, are outputted to the data storage unit of the electro-pneumatic conversion control device.