Fires stop shutter for ventilation duct - has frame with sections not closed in circumferential direction allowing alteration in diameter (SW 19.9.77)

摘要

The fire-step shutter is for use in ventilation ducts etc. and has a frame (11) formed by one or more profile sections which are not closed in the circumferential direction. This allows a reduction in the frame dia., or compress on or stretching in the radial direction. The frame can be of U- or horseshoe-section, the ends of the latter being formed by tangential extensions towards the outside from the internal sides of the frame, at the diametrically opposite points. The frame may be mounted in the extension of a supporting conduit, the extension having ends turned inwards to form a free passage whose dimensions are less than the frame diameter.