| 摘要 |
PURPOSE:To provide a line braking device operable especially only when decrease in gas pressure in a pipe line continuous during a predetermined time, by providing a gas pressure detecting device to energize or deenergize a solenoid of an electromagnetic valve and thereby to close a valve when the gas pressure is decreased to values not more than a preset value. CONSTITUTION:A line braking gas conduit 17 is connected to a gas pressure detecting device 60 in a gas pipe line, and gas pressure as detected is inputted to a control device 61. When the gas pressure is decreased to values not more than a previously set value, a solenoid 22s of an electromagnetic valve 22 is energized to connect a gas conduit 14 from the gas pipe line to a gas conduit 16, and to fed hydraulic fluid in a pressure-proof tank 24 through a flow control valve 26 and a selector valve to a cylinder chamber 35 of an actuator body, thus closing a valve. The control device 61 acts to energize the solenoid of the electromagnetic valve 22 only when the detected gas pressure continuous to decrease over a predetermined time. |
