Abstract: An apparatus for gas treatment of products rises a housing having top, bottom and side walls; a conveyor belt for transporting the products along a first path in the housing; a tunnel having perforated walls and enclosing the conveyor belt along the first path; a gas circulation device communicating with the tunnel via the perforated walls for circulating gas into the tunnel in the form of gas jets impinging upon the products carried by the conveyor belt, and out of the tunnel in a return channel back to the gas circulation device; and a gas conditioning device positioned in the return channel. At least one substantially vertical part of the connecting walls of the high-pressure chamber is removable so as to provide access to the inside of the pressure chamber, and at least one of the side walls of the housing along the high-pressure chamber may be movable so as to widen the space between at least one wall and the high-pressure chamber.