Filter assembly with paper cartridge

Claim 1

In a filter assembly including a cylindrical housing having an inlet, a co-axially disposed perforated outlet and support tube non-detachably fixed to and extending substantially the length of the housing, and a cartridge retainer nut threadably mounted on the end of said outlet and support tube, the improvement comprising: a refillable filter cartridge consisting of an inner perforated tubular member and an outer perforated tubular member, a first end cap non-detachably fixed on one end of said inner tubular member having an inner through bore slidably fixed on said support tube for supporting said inner perforated tubular member on said support tube, and an annular flange fitting over the end of said outer perforated tubular member for supporting said outer perforated tubular member in spaced relationship to said inner perforated tubular member, an annular support member supporting the outer end of the inner perforated tubular member on said support tube, a removable pleated tubular filter element disposed between said inner and said outer perforated tubular members, a second cap member detachably engaging the other end of said inner and said outer perforated tubular members, an annular resilient seal disposed between each end of said tubular filter element and each of said cap members, and said retainer nut biasing said second cap member axially along said support tube for biasing said resilient seals into sealing engagement with the ends of said tubular filter element and said cap members, and biasing said second end cap into tight engagement with said inner and outer tubular members and thereby detachably retaining said members together on said support tube.