Sealing apparatus for ovens

Claim 1

In a film treating oven having substantially wide and narrow entrance and exit openings for a substantially continuous thin film conveyed therethrough for treatment therewithin, sealing apparatus comprising: means for defining a substantially narrow slit sealingly engaged with at least one of said oven entrance and exit openings extending both across the width of and longitudinally with respect to said oven opening having an end proximal to said oven opening and a free end distal thereto, said slit being dimensioned such that the film is conveyable therethrough into or out of said oven, said slit defining means including upper and lower sealing members sealingly engaged to and extending transversely over said oven opening and having upper and lower, opposed, substantially parallel slit defining surfaces, respectively; eductor means fluidly communicating with said slit in an area adjacent to the distal end thereof for educing gases present in said slit; buffer means fluidly communicating with said slit in an area between said area wherein said eductor means communicates with said slit and the proximal end thereof for introducing an inert gas into said slit; and means for selectively adjusting the position of at least one of said upper and lower sealing members to adjust the height of said slit, at least one of said sealing members being sealingly engaged to said oven openings by a flexible seal, whereby gases leaking from the oven through the openings thereof are prevented from reaching the atmosphere external of said oven through the action of one or both of the flow of inert gas and ambient atmosphere exterior of said oven into said eductor means while the ambient atmosphere is prevented from entering the oven.