Gas filter

Claim 1

A GAS FILTER COMPRISING: (A) A GENERALLY BOX-LIKE HOUSING HAVING AN INLET IN AT LEAST ONE SIDE THEREOF AND AN OUTLET IN AT LEAST A SECOND SIDE THEREOF AND ADAPTED TO HAVE A GAS FLOW THERETHROUGH; (B) A PLURALITY OF INDIVIDUALLY REMOVABLE ELEMENTS EACH HAVING SIDE WALLS WITH A PLURALITY OF PERFORATIONS THROUGH AT LEAST A PROTION THEREOF, A CLOSED END AND AND OPPOSITELY DISPOSED OPEN END FOR THE MOVEMENT OF RELATIVELY LARGE QUANTITIES OF GAS FOR THE MOVEMENT SAID ENDS AND SIDE WALLS BEING FIXEDLY CONNECTED TOGETHER IN A UNITARY ELEMENT TO FORM A GAS DUCT; (C) MEANS MOUNTING SAID ELEMENTS WITHIN SAID HOUSING IN PARALLEL SPACED APART RELATIONSHIP WITH A PORTION THEREOF HAVING SAID OPEN ENDS IN COMMUNICATIONS WITH SAID HOUSING INLET AND THE REMAINDER HAVING SAID OPEN ENDS IN COMMUNICATION WITH SAID HOUSING OUTLET; (D) GRANULAR FILTER MATERIAL FILLING SAID HOUSING AROUND SAID ELEMENTS SO THAT ALL GAS FLOWING FROM SAID HOUSING INLET TO SAID HOUSING OUTLET PASSES THROUGH AT LEAST A MINIMUM DESIRABLE PATH LENGTH OF FILTER MATERIAL; (E) SAID HOUSING FURTHER HAVING AN OPENING WITH A REMOVABLE COVER THEREON IN A SIDE OTHER THAN THE SIDES CONTAINING SAID INLET AND SAID OUTLET AND PERPENDICULAR TO THE PLANE OF THE PERFORATED SIDES OF SAID ELEMENTS, SAID OPENING BEING ADAPTED FOR THE REMOVAL AND REPLACEMENT OF SAID ELEMENTS AND SAID GRANULAR FILTER MATERIAL; AND (F) MEANS IN JUXTAPOSITION TO THE INNER SURFACE OF THE REMOVABLE COVER FOR APPLYING A LIGHT PRESSURE TO SAID GRANULAR FILTER MATERIAL TO PREVENT SAID MATERIAL FROM PRODUCING VOIDS THEREIN WHEN SETTLING.