that fragment retention film will not necessarily
hold glass fragments together when subjected to very
high blast pressures, and the designer may therefore
want to consider alternate methods for protection of
personnel. The application of film to glass
generally allows projectiles, fragments, or bullets
to pass through; however, the film does reduce
spalling of the glass associated with a projectile
passing through the film.
The film is available in 0.05 mm (0.002 in.), 0.10
mm (0.004 in.), 0.18 mm (0.007 in.), 0.20 mm (0.008
in.), 0.25 mm (0.010 in.), and 0.30 mm (0.012 inch)
thicknesses. A minimum thickness of 0.10 mm (0.004
inch) film is acceptable for fragment retention.
The use of greater than 0.10 mm (0.004 inch) film
thickness and/or factory laminated films of 0.10 mm
(0.004 inch) or greater may provide more protection
for occupants from flying fragments of glass but may
not be warranted for low blast pressure. The
designer must investigate window frames and building
components adjacent to the glazed opening for
transfer of the blast load when using 0.18 mm (0.007
inch) and thicker films.
The properties of fragment retention film and/or the
adhesive may change over time, effecting the film's
capacity to retain fragments. Testing has shown the
film retains fragments up to 7 years of use.
The application of film to glass provides some
resistance against impacts from hammers, rocks,
clubs, or thrown objects. An impact on the film
reinforced glass creates a hole approximately the
size of the impacting object. Therefore, several
impacts are needed to make a hole large enough for
entry. The use of greater film thickness and/or
factory laminated films provides more resistance
against these impacts.
Tints and reflective films can improve the thermal
energy performance of a building. However, darkly
tinted and reflective films can cause internal heat
buildup and internal stresses in the glass resulting
in a weakened glazing system. If reflective films
are used to reduce visibility into a facility, also
provide curtains or shades for night use because
films are not reflective when the light level on the
exterior side of the film is less than that on the
interior side.
**************************************************************************
Fragment retention film shall be polyester, polyethylene terephthalate, or
a composite. Fragment retention film shall be optically clear and free of
waves, distortions, impurities, and adhesive lines. The film may be a
single layer or laminated. Lamination of the film shall only occur at the
factory of the fragment retention film manufacturer. The film shall
include an abrasion resistant coating on the surface that does not receive
the film adhesive. Fragment retention film shall be a minimum thickness of
SECTION 08850
Page 6
Previous Page
