| 摘要 |
<p>In one aspect of the invention a filter structure (55b, 57) for filtering a solid from a liquid (3) has a body which has an upstream outer surface (61, 65), a downstream outer surface (63, 67), is permeable to the liquid, is adapted to selectively filter the solid from the liquid on passage therethrough in a downstream direction, and is impermeable, or substantially impermeable, to a vent gas when wetted by the liquid. A section (85) of the body which extends from the upstream outer surface to the downstream outer surface is impermeable, or substantially impermeable, to the liquid and permeable to the vent gas so as to provide a pathway for the vent gas to pass in a downstream direction through the body. In a second aspect of the invention a filter sheet (55b) for filtering a solid from a liquid (3) has a body which has an upstream outer surface (61) and a downstream outer surface (63). A first section of the body extending from the upstream outer surface to the downstream outer surface is permeable to the liquid, adapted to selectively filter the solid from the liquid on passage therethrough in a downstream direction and impermeable, or substantially impermeable, to a vent gas when wetted by the liquid. A second section (85) of the body extending from the upstream outer surface to the downstream outer surface is impermeable, or substantially impermeable, to the liquid and permeable to the vent gas as to provide a pathway for the vent gas to pass in a downstream direction through the body. The filter structure or sheet thus incorporates means by which vent gas can pass to the downstream side of the filter structure or sheet and assist in recovery of the filtrate from the downstream side.</p> |
