Ballast frames for maintaining flexible mesh screen vents unclogged

摘要

A lightweight ballast frame with a metal rim spanned by one or more metal mullions is loosely anchored at several points to a flexible screen mesh covering a vent formed in an enclosure defining a collection chamber and providing an escape portal for the exhaust airstream which has deposited entrained debris in the chamber. The ballast frame resists outward ballooning of the flexible screen caused by the airstream, and promotes scavenging of debris adhering to the interior of the flexible screen.