Chemical filter for use in a cab ventilation system

Claim 2

A cab ventilation system comprising a plurality of walls defining an air inlet chamber having a rectangular inlet opening in one of said walls, said one of said walls defining flange means surrounding the opening and defining an abutment surface facing outwardly of the opening and surrounding the opening, first resilient sealing means attached to the abutment surface and surrounding the opening, a dust filter having a rectangular casing having outer dimensions such that an outermost edge of the casing surrounds the opening and lies adjacent the flange means, and filter screen means defined inwardly of the casing, means mounting the casing such that it can be moved from an open position remote from the opening to a closed position in which air drawn into the opening passes through the dust filter, and a solid sorbent filter comprising a container with a length and width arranged to fit into the opening inside the flange means, said container having a thickness receiving therein a solid sorbent filter material, a flange surrounding the container at one face of the container such that the thickness of the container projects into the opening with the flange adjacent said abutment surface and in contact with said first resilient sealing means and second resilient sealing means attached to a surface of said flange remote from said first resilient sealing means and surrounding the container whereby the flange can be inserted between the dust filter and said abutment surface with said first resilient sealing means between said abutment surface and said flange and said second resilient sealing means between the flange and said casing.

Claim 3

The invention according to claim 1 wherein the sealing means is attached to the flange on the side thereof remote from the container.

Claim 4

The invention according to claim 1 wherein the faces of the container are parallel and wherein said flange means is co-planar with one of said faces.

Claim 5

The invention according to claim 1 wherein said faces include perforate screens therein through which air can pass while retaining within the container a particulate absorption material.

Claim 6

The invention according to claim 1 wherein the absorption material is chosen from the group consisting of activated charcoal, Fluoricil (Trademark) and Tenax (Trademark).

Claim 7

The invention according to claim 1 wherein the dust filter is hinged along one edge to said chamber whereby the filter can be pivoted away from the opening to expose said sorbent filter.

Claim 8

The invention according to claim 1 wherein said chamber is mounted on the cab at a position adjacent the roof thereof and extending outwardly to one side thereof and wherein the dust filter and the sorbent filter are arranged in said chamber substantially lying in a horizontal plane and arranged such that air drawn into said chamber moves vertically upwardly through said filters.

Claim 9

A cab ventilation system comprising a plurality of walls defining an air inlet chamber having a rectangular inlet opening in one of said walls, said one of said walls defining flange means surrounding the opening and defining an abutment surface facing outwardly of the opening and surrounding the opening, first resilient sealing means attached to the abutment surface and surrounding the opening, a dust filter having a rectangular casing having outer dimensions such that an outermost edge of the casing surrounds the opening and lies adjacent the flange means, and filter screen means defined inwardly of the casing, means mounting the casing such that it can be moved from an open position remote from the opening to a closed position in which air drawn into the opening passes through the dust filter, and a solid sorbent filter comprising a container with a length and width arranged to fit into the opening inside the flange means, said container having a thickness receiving a solid sorbant filter material therein, a flange surrounding the container at one face of the container such that the thickness of the container projects into the opening with the flange adjacent said abutment surface and in contact with said first resilient sealing means and second resilient sealing means attached to a surface of said flange remote from said first resilient sealing means and surrounding the container whereby the flange can be inserted between the dust filter and said abutment surface with said first resilient sealing means between said abutment surface and said flange and said second resilient sealing means between the flange and said casing, wherein one side face of the container includes opening means whereby said solid absorption material in particulate form can be inserted and removed.

Claim 10

A cab ventilation system comprising a plurality of walls defining an air inlet chamber having a rectangular inlet opening in one of said walls, said one of said walls defining flange means surrounding the opening and defining an abutment surface facing outwardly of the opening and surrounding the opening, first resilient sealing means attached to the abutment surface and surrounding the opening, a dust filter having a rectangular casing having outer dimensions such that an outermost edge of the casing surrounds the opening and lies adjacent the flange means, and filter screen means defined inwardly of the casing, means mounting the casing such that it can be moved from an open position remote from the opening to a closed position in which air drawn into the opening passes through the dust filter, and a solid sorbent filter comprising a container with a length and width arranged to fit into the opening inside the flange means, said container having a thickness receiving a solid sorbant filter material therein, a flange surrounding the container at one face of the container such that the thickness of the container projects into the opening with the flange adjacent said abutment surface and in contact with said first resilient sealing means and second resilient sealing means attached to a surface of said flange remote from said first resilient sealing means and surrounding the container whereby the flange can be inserted between the dust filter and said abutment surface with said first resilient sealing means between said abutment surface and said flange and said second resilient sealing means between the flange and said casing, wherein one side face of the container includes opening means whereby said solid absorption material in particulate form can be inserted and removed.

Claim 11

The invention according to claim 8 wherein said opening means comprises substantially the whole of said side wall and hinge means along one edge of said side wall whereby the side wall can be pivoted to an opened position to allow insertion or release of the particulate material.