Guide To Avoiding Glass Failure
Glass Thickness
For purposes of this discussion, there are three basic
types of glass: monolithic, laminated, and insulating. Complete definitions of each of
these glass types are presented in a later section. The true thickness of monolithic glass
is defined as the overall thickness of the plate. Its value can be found though the use of
a micrometer, a reflective thickness gage, or an ultrasonic thickness device.
Each of
these instruments can provide reliable measurements for the purposes of the current
discussions. It should be noted that the true thickness of glass as determined through
direct measurement is usually slightly less than the nominal thickness of glass that is
used for commercial identification of the glass. The following table presents the
relationship between nominal glass thickness and the minimum true thickness of glass for
glass thickness of interest. For example a piece of glass with a true thickness of 0.223
in. (5.66 mm) should be referred to as 1/4 in. (6.0 mm) glass.
Glass
Thickness Table
|
Nominal Thickness
in. (mm) |
Minimum Thickness
in. (mm) |
Nominal Thickness
in. (mm) |
Minimum Thickness
in. (mm) |
| 3/32 (2.5) |
0.085 (2.16) |
1/4 (6.0) |
0.219 (5.56) |
| 7/64 (2.7) |
0.102 (2.59) |
5/16 (8.0) |
0.292 (7.42) |
| 1/8 (3.0) |
0.115 (2.92) |
3/8 (10.0) |
0.355 (9.02) |
| 5/32 (4.0) |
0.149 (3.78) |
1/2 (12.0) |
0.469 (11.91) |
| 3/16 (5.0) |
0.180 (4.57) |
3/4 (19.0) |
0.719 (18.26) |
The thickness of an IG unit is defined as the
individual thickness of the monolithic glass plates that make up the IG unit.
Thus if an
IG unit is constructed using two pieces of 1/8 in. (3.0 mm) monolithic glass, its
thickness should be recorded as 1/8 in. (3.0 mm).
The nominal thickness of a laminated glass unit is found by
doubling the nominal thickness of the glass plates that are incorporated into the
laminated glass unit. Thus, if a laminated glass unit is constructed using two pieces of
1/8 in. (3.0 mm) monolithic glass, the glass thickness of the laminated glass unit should
be recorded as 1/4 in. (6.0 mm). It should be noted that an ultrasonic thickness
measurement made on a piece of laminated glass will provide the thickness of only one of
the layers of the glass that is incorporated in the unit. A micrometer or optical
measurement will provide the total thickness of the laminated glass plate (thickness of
both glass plates plus the interlayer thickness).
As a general rule:
- The use of solar control film is not recommended for clear annealed
glass if the thickness of the glass exceeds 3/8 in. (10.0 mm).
- The use of solar control film is not recommended for tinted annealed
glass if the thickness of the glass exceeds 1/4 in. (6.0 mm).
- The use of solar control film is not recommended for clear or tinted
annealed laminated glass of any thickness.
Check your film manufacturer's guidelines for specific
recommendations regarding these special glass types.
Guide
Topics
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