Glazing against fire

Abstract

Conventional glazing materials used to be the weak spots in a building, but nowadays fire-resisting glass can help to limit the spread of fire. In a fire test glass is treated during the initial phase by a temperature difference between edge and middle of the pane which causes breakage to normal glass within 3 to 6 min. Wired glass is held in position by the wire net for a limited time. Special borosilicate glass without wire net withstands this temperature difference during the heating-up phase due to its low thermal expansion coefficient, 1/3 of normal glass, and an additional heat-strengthening process. Borosilicate glass also shows higher viscosity in comparison to float glass and wired glass, respectively, and, therefore, provides a long fire-rating time at temperatures above 1000 °C. Using special steel frames which can keep the melting glass within the frame, borosilicate glass is able to provide an integrity and stability up to 2 h. In case heat insulation is required, appropriate glass systems must be chosen. Two different systems are available: designs consisting of multiple layers of glass and intumescent interlayers and such using an aqueous gel in between two tempered glass panes. Some of the international certificates are shown as examples, followed by typical designs of construction elements. Typical applications of the non-wired glass types are shown in slides taken from fire doors, - screens and - windows providing fire ratings from 30 min in timber frames up to 2 h in special steel frames.