Apparatus for bag collection of dirt

Claim 1

Bag apparatus for use in a bag collector for dirt entrained in a fluid stream wherein an upstream inner bag and a downstream outer bag are concentric and closely adjacent; said apparatus comprising a housing, vertically supported in said housing, spaced iNner and outer generally cylindrical fluid permeable bags, there being an inlet for dirty fluid stream in said housing and means connected with said inlet and an open end of an upstream bag communicating with the open end of said upstream bag, there being an outlet in said housing for clean fluid communicating with said housing and spaced downstream of said outer bag, means for creating a pressure differential between said inlet and said outlet to cause a dirt collecting fluid flow between them passing through said inner and outer bags in series, means in said housing and connected in flow communication with the space between said bags for intermittingly creating a fluid pressure between said bags sufficient to partially collapse said inner bag upstream whereby said dirt is collected from the inner surface of said inner bag; bag support means secured to said inner bag holding relatively fixed at all times substantially linear longitudinally extending narrow zones of said inner bag; said zones being spaced around said inner bag circumferentially at a small number of points greater than two, whereby blow-down fluid may be intermittingly introduced between said inner and outer bags to cause said inner bag to flex inwardly to release dirt from the inner surface of said inner bag at which time said bag support means is so constructed and arranged that said pressurized fluid cannot cause opposite sides of said inner bag to touch each other during said flexing.