| 摘要 |
A seal to permit the passage of material, such as a continuous web bearing a layer of coating composition, between two zones at different gas pressures comprises a narrow passageway in communication with the two zones, a plurality of transverse ribs spaced along the longitudinal extent of the passageway, and a plurality of spaced apertures located within the troughs between adjacent ribs and communicating with a vacuum manifold for withdrawing gas from the passageway to provide a progressive change in pressure from a value at the inlet to the passageway equivalent to the pressure in the zone from which material is being transported to a value at the outlet from the passageway equivalent to the pressure in the zone into which the material is being transported. In a preferred embodiment, the seal is comprised of a smooth arcuate plate and a curved castellated shoe positioned opposite and in close proximity to the plate to define a narrow arcuate passageway therebetween. The seal is especially useful in the vacuum drying of web material having a surface coating which is especially susceptible to damage, such as a web consisting of a support coated with one or more layers of photographic emulsion.
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