Abstract: A dual gauge assembly. In an exemplary embodiment, the dual gauge assembly includes a housing. Further, a display face is disposed within the housing for displaying a pressure range. In addition, an indicating device is disposed within the housing for indicating pressure for at least two different pressure sources. Moreover, at least two ports are coupled to the housing for pneumatically coupling the at least two different pressure sources to the indicator assembly. The indicating device provides a visual indication of the at least two different pressure sources within the single housing.

Abstract: A door jamb for a cold storage room is provided with a tranverse passage for passage of air from the exterior into the interior of the cold storage room. A thin metal flap valve, specifically of stainless steel, is placed at the exterior end of the passage, seated on a flat plate. An electric heater in the passage prevents the valve from being immobilized in the closed position due to frozen condensation.