Abstract: A controllable slot ventilator comprises first and second parallel side walls which define an air passage between them. A closure member is mounted adjacent the front edges of the side walls via parallel motion links, which allow the closure member to move generally away from and towards the side walls to open and close the ventilator. At the rear of the side walls, i.e. the opposite end to the closure member, a mounting flange is fitted, whereby the ventilator is mounted to a member. When the ventilator is installed in a slot, it is preassembled and then inserted into the slot from one end.

Abstract: 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.

Abstract: 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.

Abstract: A latch mechanism for a door or the like includes first and second rotatable latch operating members which operate a latching bolt or the like. An axially movable square section spindle extends through complementary holes in both members. In an engaged position, the spindle operates both members when rotated. In a disengaged position, a circular section portion of the spindle registers with a hole in one of the members. In the disengaged position the bolt can be operated by the first member even though the second member may be prevented from rotating by means of pins. The spindle can be moved between engaged and disengaged positions by a push-rod extending out of the door. Thus, when the second member is locked it may be overriden by actuation of the rod and the first member.