| 摘要 |
A gaseous-material evacuation system includes a filter assembly (44) with a housing (56) containing filter material (58) with a downstream porous filter member (60) at a downstream side of the filter material. The filter assembly includes a valve (64) with a movable valve member (66) for moving in a direction of gas flow and having a breadth area dimension that is at least as great as that of the downstream surface of the downstream porous filter member. In a preferred embodiment, a spring member (68) presses the movable valve member (66) against the porous filter member (60), thereby stopping gaseous flow, but yields when gaseous materials are driven through the filter at a predetermined pressure. The valve member is mounted in a sub-compartment (72) of the housing, which is of a single-piece housing member.
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