| 摘要 |
A low actuation pressure bar vent for use in a tool string having low pressure therein. The vent includes a body portion and a piston slidingly disposed in the body. The piston and body define a first cavity therebetween and a second cavity therebetween, spaced from the first cavity. The body further defines a plurality of transverse ports therethrough providing communication between a body central opening and a well annulus. When in a closed position, the piston sealingly closes the ports. In a first embodiment, the first cavity has a spring disposed therein. The body also defines a second plurality of ports therein providing fluid communication between the first cavity and the well annulus. Pressure in the well annulus and the spring bias the piston toward an open position uncovering the ports. In an alternate embodiment, a pressurized gas biases the piston. The second cavity is filled with a fluid such that movement of the piston is prevented. A break plug is positioned in the piston and includes a shearable portion, which when sheared, allows the fluid in the second cavity to be released to the tubing string. The biasing force moves the piston to the open position, displacing the fluid from the second cavity. During assembly, an assembly plug holds the piston closed.
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