Experimental Investigation of Glass Breakage in Compartment Fires.
Experimental Investigation of Glass Breakage in
Skelly, M. J.
NIST GCR 90-578; 91 p. June 1990.
Journal of Fire Protection Engineering, Vol. 3, No. 1,
Sponsor:National Institute of Standards and Technology,
Available from: National Technical Information Service
Order number: PB90-244443
glass; compartment fires; windows; building fires; fire
tests; radiant heating; critical temperature
An experimental investigation has been completed which
studied the breaking of window glass by fire. The
experiments were carried out in a specially designed
compartment to achieve two-layer flows characteristic of
normal building fires. The experimental data was
collected from two test groups: the first for windows
with their edges insulated from the fire
(edge-protected) and the second for windows uniformly
heated by the fire (edge-unprotected). The results of
the edge-protected window tests indicated that the glass
breakage was caused by a critical temperature difference
between the central heated portion of the pane and the
glass edge. The experimental work showed the critical
value to be approximately 90C. After the material
properties of the glass were determined, the theoretical
findings of Keski-Rahkonen were used to obtain a value
of 70C; the difference attributed to radiative heating.
The test results also demonstrated a distinctive loss of
integrity by the windows. When breakage occurred, the
cracks spread throughout the glass, joined together and
caused at least partial collapse of the pane. The
results from the edge-unprotected window tests were
quite different. There were relatively few cracks
developed and almost no propagation across the glass.
Consequently, there was no window collapse in any of
these cases. The breakage did initiate at a consistent
glass temperature value, however, the mechanism for
these tests is not known.