| 摘要 |
A filter element (28) having a plurality of membrane layers (90, 92). The filter element has a filter member having a porous sidewall. The sidewall has an outer surface (78) and an inner surface (80) which allow a gas to flow through. A first membrane (90) is in communication with the outer surface for preventing particulate matter from penetrating the outer surface. A second membrane (92) is in communication with the inner surface for preventing particulate matter from penetrating the inner surface.
|
