Refrigerant suction line filter/filter-drier and method for the construction thereof

A method of glass constructing a filter/filter-drier to provide increased contaminant holding capacity therewithin and to enable pressure drop across said filter/filter-drier to increase gradually and provide a warning of impending need for replacement thereof, wherein said filter/filter-drier comprises a cylindrical shell, a pair of sealably attached closure members at the ends thereof, coaxially disposed inlet and outlet openings in said closure members, and a primary filter assembly, said method comprising:

• A. providing, as a part of said filter assembly, a stepped filter having a selected peripheral area, a selected facial area, and a selected internal volume which is accessible to a selected open upstream space that surrounds said stepped filter and is in flow communication with the inlet opening;
• and
• B. providing, as another part of said filter assembly, a rigid deflector member which is disposed in coaxial alignment with said inlet opening, substantially downstream thereof, and transversely thereto for protecting said stepped filter;
• and
• C. providing a sealing means for isolating said open upstream space from said outlet opening except through a plurality of openings which are in flow communication with said stepped filter, whereby an incoming refrigerant mixture enters said inlet openings, impinges upon said liquid deflector member, swirls through said upstream space, enters both said facial and said peripheral areas of said stepped filter, moves along strata within said stepped filter, and deposits its solid particles at many locations within said internal volume before passing through said plurality of openings to said outlet opening.

A filtering device for refrigeration and air conditioning systems which comprises a cylindrical shell, a pair of closure members which are sealably attached to the ends of said shell, and an inlet connector sealably attached to one of said closure members, and an outlet connector sealably attached to the other said closure member, said filtering device comprising:

• A. a filter assembly which comprises:
• 1. an inlet deflector which is disposed transversely to said shell,
• 2. a stepped filter which comprises:
• (a) a deflector filter pad, of selected shape and size, which is disposed adjacent to and downstream of said inlet deflector,
• (b) an inlet filter paid which:
• (1) is disposed adjacent to and downstream of said deflector filter pad,
• (2) is round in shape, and
• (3) has a smaller diameter than the inside diameter of said shell, said deflector filter pad differing in said shape and said size from said round shape and being of a smaller diameter than the diameter of said inlet filter pad to provide a stepped annular space which has a greater cross-sectional area in its upstream portion surrounding said deflector filter pad than in its downstream portion surrounding said inlet filter pad,
• (c) a filter pad support, disposed transversely to said shell and adjacent to and downstream of said inlet filter pad, and having a plurality of openings therethrough, all of which are covered by said inlet filter pad, and a diameter approximately equal to said inside diameter of said shell, and
• 3. means for rigidly supporting said inlet deflector, said stepped filter, and said filter pad support of said filter assembly;
• and
• B. an annular gasket which is disposed adjacent to said filter pad support and in peripheral contact with said cylindrical shell to provide sealed isolation of said stepped annular space, whereby a swirling flow of an incoming vaporous mixture, entering said inlet connector, impinging upon said inlet deflector, and swirling through said stepped annular space, is forced to enter the peripheries of said stepped filter and then to flow along strata therewithin, while depositing its solid particles at many locations along the interiors of said deflector filter pad and said inlet filter pad, before passing through said plurality of openings so that pressure build up across said filtering device is gradual and provides a warning of impending need for replacement of said device.