To provide a pleated filter member, a method and apparatus for manufacturing the same, a method for precoating or backwashing the pleated filter member and a filter having a large filtering surface area and a long life.
The filter member is a cylindrical filter member 10 having a longitudinal axial line, first and second end surfaces and a large number of longitudinal pleats 11, and each pleat has a pair of leg parts and each of the leg parts has first and second surfaces and the pleat is extended over at least 50% of the length in the axial direction of the filter member in the whole height of each leg part. The cylindrical filter member is in a laid over state wherein the first surface of one leg part is in close contact with the second surface of the adjacent leg part of the pleat over a continuous region and a first impermeable end cap is connected to the first end surface of the filter member.
WILLIAMSON KENNETH M
HOPKINS SCOTT D
GEIBEL STEPHEN A
WOLFF TERRY L
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