Abstract: The method of the invention is based on the comparison of local vapor concentrations at the inlet and outlet refrigeration ports and taking action based on that comparison. Control apparatus incorporating the invention is installed inside a refrigeration enclosure, adjacent to a port, preferably at the lowermost port. If the enclosure contains multiple ports at similar height, then each port has a form of the control apparatus attached to it. The control apparatus adjusts a flow of vapor leaving the interior of the enclosure. The control apparatus includes a duct assembly and a blower system. The bottom portion of the duct assembly is a tunnel enclosure through which a conveyor belt passes. Connected to an inside edge of the tunnel enclosure is a duct that extends upward from the conveyor belt. A blower for this duct either sucks vapor away from the conveyor belt or blows vapor from the enclosure interior toward the belt.

Abstract: Apparatus and method for purging air from open containers having a processing zone through which the containers are conveyed entering through an entrance point opening and exiting through an exit point during a residence time, including an injector for injecting a turbulent flow of purge gas into the processing zone and means for providing a laminar flow of purging gas into the processing zone, wherein the open portion of the container is exposed to the turbulent purge gas flow for at least 50 percent of the residence time.