Window drain valve

Claim 1

A window drain valve in combination with a horizontal window sill having a water drain aperture in its lower surface and an aperture in its external face, said window drain valve having a body section disposed below said sill and also having a cover with an inlet slot formed therein being in communication with a liquid-containing inflow compartment formed in said body section, said inlet slot also being aligned with said drain aperture, said window drain valve having an overflow outlet aperture in communication with a liquid-containing outflow compartment formed in said body section, said overflow outlet facing horizontally and disposed at a level below said drain aperture while being aligned with said aperture in the external face, wherein a downwardly projecting web from said cover divides said body section into said inflow and outflow compartments, said compartments being in liquid communication with each other, said compartments having upright walls extending from a bottom wall to said cover, wherein a float valve member is provided in said inflow compartment and is arranged so that an increase in external air pressure against said outlet reduces the level of liquid in said outflow compartment and correspondingly raises the level of liquid in said inflow compartment to move said float valve member toward a position in which it closes said inlet, said downwardly extending web being of sufficient length to ensure that said float valve member will reach its closed position before the liquid in said outflow compartment has dropped to the lower extremity of said web, and saId overflow outlet being at a level such that liquid entering through the inlet passes under the web and out the inlet without raising the float valve member to a closed position.