Abstract: An apparatus for treating a travelling web of material in a predetermined gaseous atmosphere comprising a chamber (1) through which a moving web of material (2) is transported from an inlet at a first end of the chamber (1) to an outlet at a second end and a means for introducing and controlling gas (5) intended to provide said predetermined gaseous atmosphere within said chamber (1), wherein said inlet and outlet each comprise a sealing means (4a, 4b) designed to enable passage of said web of material (2) therethrough whilst minimising the ingress of an external gas boundary layer (3) around said web of material (2) characterised in that said apparatus also comprises one or more re-circulation channels (7, 8) adapted to re-circulate gases within said chamber (1) from the second end of the chamber to the first end of the chamber thereby negating or substantially negating any pressure difference within the chamber (1) between said inlet and outlet.

Abstract: An apparatus for treating a travelling porous web of material in a predetermined gaseous atmosphere comprising a process chamber (1) through which a moving web of porous material (2) is transported from an inlet at a first end of the process chamber (1) to an outlet at a second end of the process chamber (1) and a means for introducing and controlling required gas intended to provide said predetermined gaseous atmosphere in the chamber, (1). The inlet and outlet each comprise a sealing means (4a, 4b) designed to enable passage of the web of material therethrough whilst minimising the ingress of an external gas boundary layer around said material.

Abstract: An apparatus for treating a travelling web of material in a predetermined gaseous atmosphere comprising a chamber (1) through which a moving web of material (2) is transported from an inlet at a first end of the chamber (1) to an outlet at a second end and a means for introducing and controlling gas (5) intended to provide said predetermined gaseous atmosphere within said chamber (1), wherein said inlet and outlet each comprise a sealing means (4a, 4b) designed to enable passage of said web of material (2) therethrough whilst minimising the ingress of an external gas boundary layer (3) around said web of material (2) characterised in that said apparatus also comprises one or more re-circulation channels (7, 8) adapted to re-circulate gases within said chamber (1) from the second end of the chamber to the first end of the chamber thereby negating or substantially negating any pressure difference within the chamber (1) between said inlet and outlet.