| 摘要 |
A valve assembly for sealing a port of a housing includes a primary sealing member and a secondary sealing member mounted to a valve body. Valve body includes a lower body with an upper portion depending from the body having a cross sectional diameter less than the upper body, and a lower portion depending from the upper portion having a cross sectional diameter less than the upper portion. The primary member includes apertures and is slidably mounted to the upper portion, and the secondary member is mounted to the lower portion. In a closed position the secondary member seals against the primary member, and the primary member seals against the port. Downward movement of the valve body unseals the secondary member from the primary member allowing venting through the apertures, and then unseals the primary sealing member from the port allowing full venting through the housing. |
