Multiglazed window unit

Claim 1

A multiglazed window comprising at least a pair of glass sheets secured by frame means in spaced relation to define a hermetically sealed air chamber therebetween, said frame means having normally vertical side members, means effective to limit the pressure differential between said chamber and the surrounding atmosphere to a predetermined value comprising vent means having liquid seal means associated therewith operative to normally close said vent means but responsive to such pressure differential to permit the passage of air therebetween, said seal means including a vessel mounted on one of the vertical side members of the frame and having a pool of liquid sealant therein, a pair of tube members extending down into said liquid with their lower ends normally below the sealant level, each of said members having enlarged portions intermediate their extremities and normally disposed somewhat above the sealant level, one of said tube members communicating with atmosphere and the other communicating with said sealed air chamber, and a filter plug in each of said members permitting passage of air but restricting passage of foreign material.