| 摘要 |
A method and apparatus for safely controlling fluid flow comprises a safety control valve that automatically stops fluid flow upon a fluid pressure failure, requires two-handed manual operation to open the valve, and the valve being biased to prevent being left in the open position in the absence of fluid pressure. The safety control valve comprises a valve body that coaxially receives therein a slidable spool manually operable in an axial direction between a closed valve position and an open valve position. The valve further comprises a spring and a spring biased coaxial safety piston capable of axial movement along the spool and being pneumatically connected to a fluid supply line. In the absence of fluid pressure, the spring biases a safety piston against a contact surface of the spool so as to bias the spool into the closed position thereby preventing fluid flow through the valve. In the presence of a sufficient fluid pressure in the fluid supply line, the fluid pressure biases the safety piston against the spring and away from the contact surface of the spool so as to prevent movement of the spool between the open and closed positions.
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