The invention concerns an installation wherein is performed a crosslinking operation for a coating such as an ink or a varnish through ultraviolet radiation or electronic beam, in the presence of a gas mixture with controlled oxygen residual content. The installation comprises a chamber including one or more UV lamps or a source of accelerated electrons, required for performing the crosslinking operation, and is characterized in that it comprises an input device adjacent the chamber comprising at least the following three components, viewed successively by the product moving to be treated: a labyrinth system, means for injecting an inert gas forming a gas knife and a channel.