Abstract: A latch suitable for use on the door of a walk-in refrigerator can be opened from the exterior thereof and in addition from the inside of the cabinet as well as by means of an electrical signal. The latch is provided with a vapor barrier to prevent flow of water vapor along that part of the mechanism by means of which the latch is operable from the interior of the cabinet, flow of water vapor presenting the danger of frost-formation in said mechanism which could adversely affect the operation thereof. Optionally, the latch is provided with a switch which is closed on operation of the latch to activate an external device such as a vent port or an alarm signal.

Abstract: A shielded vent port for equilization of the pressure on opposed faces of a wall comprises a frame for fitting into an opening in said wall, a conduit through said frame, a sloping plate in said conduit, said plate being sealed against the walls of said conduit and having a large aperture therethrough, and a riser lying against the upper face of said sloping plate, said riser preventing flow of air in a downward direction through said plate and being movable away from said plate to permit flow therethrough in an upward direction. To provide for flow of air through said wall in either direction, the frame may have two conduits therethrough with a sloping plate and a fitted riser in each, the planes of said plates sloping in opposed directions. The shield may be lifted away from the plate to permit flow of air therethrough by an excess of pressure below the plate or by a solenoid in response to an external signal.

Abstract: A latch suitable for use on the door of a walk-in refrigerator can be opened from the exterior thereof and in addition from the inside of the cabinet as well as by means of an electrical signal. The latch is provided with a vapor barrier to prevent flow of water vapor along that part of the mechanism by means of which the latch is operable from the interior of the cabinet, flow of water vapor presenting the danger of frost-formation in said mechanism which could adversely affect the operation thereof. Optionally, the latch is provided with a switch which is closed on operation of the latch to activate an external device such as a vent port or an alarm signal.