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US 4,188,197 AGranted
Particulate filtering
AssigneeDennison Manufacturing Company
InventorsSuresh D. Amberkar, Elwood F. Hansen, David E. Hansen
Life of this patent
Estimating the term…
Abstract
A filter bag for dry copiers, i.e. copiers which employ particulate toner material. The bag comprises a filter element and a protective cover of porous non-woven material which imparts negligible resistance to air flow.
Claims10
A filter medium comprising three elements, the first of which comprises a plurality of successive layers of different densities, the second of which is formed by fibers having different deniers;
- and the third of which is made up of glass fibers;
- said first element having a porosity greater than that of said third element, and said second element having a porosity range between a value above the lowest porosity of said third element and below the highest porosity of said first element.
A bag for filtering particulate matter comprising
- a filter medium forming the walls of said bag and a flexible porous protective shield separate from and surrounding said medium and having a greater porosity than that of said medium;
- said porous shield being of filamentous material having a weight below about 0.8 ounces per square yard.
Dependencies are inferred from the claim text.