Abstract: A drain valve for draining liquid from an enclosed space comprises a movable plunger, which is movable between a closed position in which the plunger does not allow liquid to flow through the drain valve, and at least one open position, in which the plunger allows liquid to flow through the drain valve; and an elastic element, which is configured to urge the movable plunger into its closed position. The plunger is provided with at least one duct extending through the plunger and allowing fluid to flow through the drain valve when the plunger is positioned in its closed position, wherein said at least one duct is closed by a semi-permeable medium, which is permeable for air and water vapor and impermeable for liquid water.

Abstract: A light unit with an extended light emission surface includes a light source, and a flat light distribution body having a first principal surface and a second principal surface disposed on opposite sides of the flat light distribution body, wherein the light source is positioned outside of the flat light distribution body, with light emitted by the light source being coupled into the flat light distribution body and being propagated within the flat light distribution body via total internal reflection at the first and second principal surfaces.

Abstract: A light unit with an extended light emission surface includes a light source, and a flat light distribution body having a first principal surface and a second principal surface disposed on opposite sides of the flat light distribution body, wherein the light source is positioned outside of the flat light distribution body, with light emitted by the light source being coupled into the flat light distribution body and being propagated within the flat light distribution body via total internal reflection at the first and second principal surfaces.