Carlon P&C Duct and Telephone Duct Expansion and Contraction - Low Res - Manual

P&C ® Duct and Telephone Duct – Expansion & Contraction
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Expansion & Contraction
When duct temperature variations are anticipated during the
installation of Carlon P&C
® Duct and Telephone Duct, allow
extra duct footage at each tie-in for contraction. Terminated
duct runs should be covered with backfill from tie-in point
toward the end of the duct run. If the trench must be left
open, don’t terminate the run. All plastic duct may expand
or contract as concrete is poured and cured. When placing
concrete encasement, always encase from one end of the duct
section toward the other end of the section, to allow the free
end to move. Never encase from each end of the section
toward the center.
The coefficient of thermal expansion of Carlon P&C Duct
and Telephone Duct is 3.30 x 10
-5 in/in/°F. The following chart
indicates what expansion or contraction can be expected at
various temperature changes.
Type D Telephone Duct is designated specifically for use
in bridge crossings and exposed applications. Using the
expansion/contraction chart, calculate the number of expan-
sion joints required. Expansion joints provide a 6" allowance
for expansion/contraction. Utilize one expansion joint for each 100 feet of exposed length for most installations.
The duct should be free to move during expansion/contraction;
the barrel should be securely clamped and the piston should
be aligned properly with the barrel for easy movement.
Bridge Crossings and Exposed Applications
Expansion/Contraction Chart
47
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