Guide To Avoiding Glass Failure
Solar Exposure
When glass is subjected to the effects
of solar radiation, the immediate result is an increase in the
temperature of the glass. Depending upon shading and support
conditions, the influx of solar radiation can lead to
significant variations in temperature across the surface of
the glass. Variations in glass surface temperature lead to the
introduction of thermally induced stresses.
The level of solar exposure depends to a
large extent on orientation of the glass. North facing glass
receives the least amount of solar exposure and as a result
thermal fractures associated with Northerly facing glass tend
to be rare. All other exposures tend to experience sufficient
solar insulation to experience significant thermally induced
stresses. Glass that has a Southerly exposure tends to
experience the most dramatic overall heat build up during the
course of a day. Depending upon the conditions associated with
the installation, thermal fractures can be expected on glass
with southerly exposure. Glass that faces toward the East has
the possibility of experiencing the early morning effects of
solar exposure. Such exposure can be extremely critical during
winter months when glass that has had several hours to reach a
very low uniform temperature on a cold winter night is
suddenly subjected to a blast of early morning sunlight.
This
situation often leads to thermal fracture if the conditions
associated with the glass are conducive to glass failure.
West
facing glass is subjected to the afternoon affects of the
sunlight which depending upon conditions of the installation
can lead to similar significant thermal stresses. Therefore,
it is important to note the exposure (N, NE, E, etc.) of each
glass plate. The possibility for thermal fracture can usually
be discounted for glass plates with NW, N, or NE exposures in
the northern hemisphere and the SE, S, or SW exposures in the
southern hemisphere. However, it must be considered for all
other exposures.
Guide
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