| 摘要 |
A valve assembly includes a housing having a first chamber, a second chamber, and a valve seat disposed therebetween. A valve head disposed in the housing and is moveable between an open position and a closed position. The valve head defines a bore extending along an axis from the first chamber to the second chamber when the valve head is in the closed position. A valve stem is disposed in the bore and is coupled to the valve head in the bore for moving the valve head between the open and closed positions. The valve assembly allows for selective fluid communication between the first and second chambers to alleviate pressure differences between the first and second chambers. In one embodiment, the valve stem moves in the bore between a sealed position and an unsealed position. In another embodiment, a check valve is disposed in the bore. |
