Ventilators

摘要

A canopy for use with a ventilator slot extending through a window frame has pressure differential responsive flow control means arranged to progressively close the flow passage through the canopy as the pressure differential increases, thus preventing draughts. The canopy has a body with an inlet and an outlet and a bowed wall therebetween. A normally straight baffle strip is attached to the center of the wall and there are non-aligned apertures in the wall and the baffle respectively. When the pressure differential between the inlet and outlet is low, the baffle is well-spaced from the wall but as the pressure differential increases the baffle is bowed progressively towards the wall against the inherent bias of the strip to progressively close the flow path through the apertures.