Emergency shutoff valve actuator and emergency shutoff device

摘要

PROBLEM TO BE SOLVED: To provide an emergency shutdown valve actuator operated under a simple configuration.SOLUTION: This invention comprises a piston rod 407 connected to a piston 403 of a cylinder 401 and a valve shaft 201 of a shutdown valve 2 for rotatably driving the valve shaft by opening or closing the shutdown valve as being displaced in response to the piston; a high pressure gas supply mechanism 6 operated by an external signal, discharging gas to a first cylinder chamber 405a of the cylinder and moving the piston toward the valve opening position; a piston pressing member 409 movably arranged at a second cylinder chamber 405b; a biasing member 411 for biasing the piston pressing member toward the piston; and an engaging mechanism 5 for use in engaging with the piston pressing member, operated by the external signal to release the piston pressing member, causing the piston pressing member to press the piston present at the valve closing position to press by a biasing force by the biasing member and to move the piston toward the valve opening position.SELECTED DRAWING: Figure 1