METHOD FOR CLOSING FLUID PASSAGE, WATER HAMMERLESS VALVE ANDWATER HAMMERLESS CLOSING DEVICE

摘要

A fluid passage is emergency-closed in a short time without causing water hammer by extremely simple device or operation. A water hammerless closing device comprises an actuator-operated valve provided in the fluid passage an d an electro-pneumatic converter for supplying a two-step actuator working pressure Pa to the actuator-operated valve, a vibration sensor secured removably to the upstream-side pipe-line of the actuator-operated action valve, and a tuning box receiving a vibration detection signal Pr from the vibration sensor and delivering a control signal Sc for controlling the magnitude of the step working pressure Ps~ of the two-step actuator working pressure Pa to the electro-pneumatic converter, and regulating the control signal Sc to deliver the two-step actuator working pressure Pa of the step working pressure Ps~ for bringing the vibration detection signal Pr substantially to zero from the electro-pneumatic converter.