| 摘要 |
PURPOSE:To make it possible to stop the leakage of gas fuel during earthquake or ground subsidence, by automatically closing a shut-off ball valve with the use of the pressure of gas fuel. CONSTITUTION:A pressure detector 24 detects the total pressure and static pressure of a gas fuel. Further, the total pressure and static pressure are led to both sides of a diaphragm 31 through a pressure detecting valve 26 and a pressure duct 28. The diaphragm 31 is coupled with a spindle 30 of a change- over valve 27, and is therefore connected with an actuator 29 for driving a drive lever 23 of a ball valve 11 through the change-over valve 27. Further, an arrangement is made such that when a gas fuel duct clacks, the differential pressure between the total pressure and the static pressure of the gas fuel allows the diaphragm 31 to be puled up. With this arrangement, it is possible to prevent fuel gas from leaking.
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