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VAV Boxes and Controls Replacement in Academic Building at Gordon College
Barnesville, Georgia
C.
Construct T's, bends, and elbows with radius of not less than 1-1/2 times width of duct on
centerline (Figure 2-2, Type RE-3 and Figure 2-5,2-6). Where there is not sufficient space and
at the Contractor's option in all other locations, rectangular elbows with turning vanes may be
substituted.
D.
For turning vane construction see Figure 2-2, Type RE-2 and Figure 2-3 and 2-4. Provide at all
square elbows in supply, return and exhaust ductwork and where noted.
E.
Increase duct sizes gradually, not exceeding 15 degrees divergence wherever possible.
Divergence upstream of equipment shall not exceed 30 degrees; convergence downstream shall
not exceed 45 degrees. Provide Type 2 or Type 3 offsets where required. See Figure 2-9.
F.
Provide easements where low pressure ductwork conflicts with piping and structure. Where
easements exceed 10 percent duct area, split into two ducts maintaining original duct area. See
Figure 2-10 for easement construction.
G.
All branch take-offs of rectangular ducts shall be made with "45 degree entry" fitting in
accordance with Figure 2-8 or by means of "parallel flow branches" with turning vanes and
locking splitter dampers (Figure 2-7) where indicated. All branch take-offs of round ducts shall
be made with "Bellmouth take-off collar,” or “45° take-off collars" as specified in Section
15820.
END OF SECTION 15815
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