| 摘要 |
PURPOSE:To prevent a safety valve from being actuated by increasing the opening degree of a pressure regulating valve gradually when the secondary pressure of the pressure regulating valve is abnormally increased at the opening of a shut off valve. CONSTITUTION:At an emergency time, an electromagnetic valve 7 is actuated and the shut off valve 5 is closed. A switching valve 17 sets up a conduit 19 to atmospheric pressure, so that the pressure control valve 10 is closed and feeding of fluid to a machine device 1 is interrupted. When the valve 7 is energized to feed the fluid to the device 1, the valve 5 is opened and the pressure P1 of a conduit 3 is made equal to the pressure P0 of a conduit 2. At the time, the switching valve 17 is turned to a switching position 17b and the valve 10 starts its pressure control operation on the basis of the actuation of a pressure controller 13 corresponding to the output of a pressure transmitter 11. Consequently, the valve 10 is gradually opened from the fully closed status and the pressure P2 of a conduit 4 reaches a set value Ps. Thus, the safety valve 15 is prevented from being actuated. |
