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Window Breakage Induced by Exterior Fires.


pdf icon Window Breakage Induced by Exterior Fires. (2954 K)
Mowrer, F. W.

NIST GCR 98-751; 46 p. June 1998.

Available from:

National Technical Information Service
Order number: PB98-148208

Keywords:

building fires; windows; ceramics; fire resistant materials; heat flux; glazing materials; glass; large scale fire tests; occupants

Abstract:

Exterior fires can penetrate building envelopes via a number of pathways to become interior fires. One pathway is through windows and other glazed openings that have been broken by fire induced stresses. A number of small- and large-scale experiments have been conducted to evaluate the performance of various window assemblies, glazing materials and potential protective treatments under the influence of imposed radiant heat fluxes ranging from 0.2 to 1.8 W/cm2. Window assemblies include single- and double-pane windows with wood, vinyl and vinyl-clad wood frames. Glazing materials include ordinary single- and double-strength plate glass, tempered glass and a heat-resistant ceramic glass. Potential protective treatments include insect screens, vinyl film sun shades and aluminum foil. The application of aluminum foil over the exterior side of a window was found to be an effective treatment to prevent window breadage induced by an exterior fire. This simple treatment could be implemented by homeowners or other occupants of existing buildings in advance of an approaching exterior fire. This simple treatment could be implemented by homeowners or other occupants of existing buildings in advance of an approaching exterior fire. Tempered glass and heat-resistant ceramic glass did not break under the influence of the imposed heat fluxes; mounted in a suitable fire resistant frame, they could be candidates for use in new windows where exposure to an exterior fire is expected. Vinyl-frame windows did not perform well under the exposure of imposed heat fluxes. The vinyl frames and sashes of these windows lost strength, distorted and sagged, permitting openings to develop. Consequently, vinyl-frame windows would not be suitable for use with fire resistant glazing materials.