Filter having automatic means actuated by differential pressure, which means are easily accessible

Claim 1

In a filter comprising a cylindrical casing encircling a vertical axis, a plurality of filter elements equally spaced about said axis within said casing, and pressure-responsive means actuated by the pressure of fluid being filtered to successively and cyclically clean said filter elements by forcing countercurrent fluid therethrough, the improvement according to which said pressure-responsive means comprises: a piston mounted to reciprocate horizontally between two positions inside a cylinder mounted to rotate within said casing in a horizontal plane above said filter members, the portion of said casing between said cylinder and the top of the casing being free of internal obstructions to upward removal of said cylinder and filter members from said casing, means for reciprocating said piston including resilient meaNs biasing said piston toward one position and a distributor head actuated by said piston for movement between a first position subjecting at least part of one side of said piston to atmospheric pressure and a second position subjecting said at least one part to the pressure inside said casing, and a pressure chamber carried by said cylinder, the pressure in which is increased above atmospheric pressure by movement of said piston to one of said two piston positions, the lower end of said pressure chamber terminating in annular sealing means which is brought into alignment with the periphery of each of said filter elements successively as said cylindrical member rotates, whereby fluid from said pressure chamber is forced through each of said filter elements in succession to clean said filter elements.