Construction:
i. It consists of grooved, drainage rod on which a number of metallic ring are packed.
ii. The rings are usually of stainless steel and have 0.8 mm outer thickness, 15 mm inside diameter & 22 mm outer diameter.
iii. The rings have a number of semicircular projections on one surface and when they are packed on the rod, the opening between the rings about 0.2 mm.
Working:
i. The entire assembly is placed inside a pressure vessel, containing the liquid to be filtered.
ii. When vacuum is applied liquid will flow from outside to inside.
iii. In this form a metafilter can only be used as strainer for coarse particle, but for separation of fine particle a bed of suitable material kieselguhr is used.
iv. In this way pack of ring act as a base on which the fine filtration medium is supported
Diagram: