For overseas work the following subparagraph will
also be added:
1. When units other than United States manufacturer
are proposed for use, the manufacturer shall prove
successful use of the insulating window units in
aircraft control tower cabs.
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Control tower glass units shall be of sizes required to properly fit
aluminum frames. Tolerances and clearances for units shall be designed to
prevent the transfer of stress in aluminum frames to the glass. Resilient
setting blocks, spacer strips, clips, bolts, washers, angles, glazing
sealants, and resilient channels or cemented-on-materials shall be of the
type recommended in the glass manufacturer's approved written instructions.
Edges and corners of units shall not be ground, nipped, cut, or fitted
after leaving the factory.
2.2.2.1
Control Tower Insulating Glass
Insulating glass units for air traffic control towers shall meet the wind
load design requirement of [_____] kPa, [_____] psi, as determined in
accordance with ASCE 7. Insulating glass shall be Class A preassembled
units of dual-seal construction consisting of two lites of glass separated
by a dark bronze aluminum, steel, or stainless steel, spacer with desiccant
and dehydrated space conforming to ASTM E 773 and ASTM E 774. Spacer shall
be roll-formed, with bent or tightly welded or keyed and sealed joints, to
completely seal the spacer periphery to eliminate moisture and hydrocarbon
vapor transmission into airspace through corners. Primary seal shall be
compressed polyisobutylene. Secondary seal shall be silicone. Insulating
glass units shall be fabricated for use at an elevation of [_____] meters
[_____] feet above mean sea level and [_____] meters[_____] feet above
grade. Within bottom 1/3 of one of the vertical edges of each unit, the
manufacturer shall install an open 305 mm 12 inch long capillary/breather
tube for pressure equalization. The insulating glass units shall be free
of parallax or optical distortions. The manufacturer's identifying label
shall be permanently affixed to both exterior surfaces of the glass units.
The insulating glass units shall be a total thickness of 26 mm (1 inch) 1
inch consisting of two 6 mm (1/4 inch) 1/4 inch thick panels and air space,
or a total thickness of 32 mm (1-1/4 inch) 1-1/4 inch consisting of two 10
mm (3/8 inch) 3/8 inch thick panels and air space, or a total thickness of
38 mm (1-1/2 inch) 1-1/2 inch consisting of two 13 mm (1/2 inch) 1/2 inch
thick panels and an air space, as required to meet the wind loads
indicated. Glass type shall be as follows.
2.2.2.2
Control Tower Heat-Absorbing Insulating Glass
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NOTE: Coordinate with paragraph Heat Absorbing
Glass.
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Heat-absorbing insulating glass shall consist of two glass panels separated
by an air space and shall conform to ASTM C 1036, Type I, transparent flat
glass, Style A, Quality q3 - glazing select. Interior glass shall be Class
1-clear and exterior glass shall be Class 2-tinted green. Glass
performance shall be minimum Visible Transmittance of [70.8] [_____]
percent for each panel and K-Value of 3.07 R-Value of 1.85 for the unit.
SECTION 08800
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