Air lock, particularly to permit drying of a printed web in a controlled atmosphere

Air lock to separate ambient air from a confined space (1) within a chamber permitting non-contacting movement of a web between the ambient air and the confined space, particularly for movement of freshly printed paper web subject to smearing into and out of said chamber defining the confined space, in which vacuum or gas compositions prevail which differ from ambient atmospheric condition or composition and especially for hardening, curing or drying of printing ink on a paper web,

• comprising
• two plate elements (12, 13;
• 32, 33) positioned parallel to each other and spaced from each other to form a web passage slit which is contiguous with a pass-through slit into the chamber, to permit passage of the web through the slit and into the chamber,
• each of said plate elements being formed with a plurality of essentially similarly shaped and dimensioned, symmetrical grooves or recesses, or depressions (7-11;
• 29) extending transversely to the direction of movement of the web, mutually aligned and positioned symmetrically with respect to the pass-through slit into the chamber and located along the path of travel of the web from outer edges of the plates to the pass-through slit;
• and means (14-23) for exclusively providing suction, communicating with the recesses of both of the plates to apply equal suction to the web both from the top as well as the bottom thereof and thereby draw air leaking through said slit into said web passage above the web and below the web;
• said plates being sealed laterally of said slit to confine the suction to the slit;
• the two plate elements being positioned immediately adjacent the pass-through slit of the chamber, and sealed to the side wall (6) of the chamber to form an air throttle or choke with respect to air communication between the chamber and ambient air.