Proper position, Setting position of piston – Carlon Expansion Joints for PVC Rigid Nonmetallic Conduit User Manual
Page 3
Proper Position
Expansion joints are usually installed in a horizontal position. However, if they must be put in a vertical
application, the open end should be securely fastened in the down position. The expansion coupling must
be installed close to the top of the run with the barrel pointing down, so that rain water does not enter
into the opening. The lower
end of the conduit run should
be secured at the bottom.
This will result in an upward
movement due to the length
change caused by
temperature variations.
Length
Inches of Expansion Allowance Needed
of Run
for Temperature Changes of:
(Feet)
60°F
80°F
100°F
120°F
140°F
25
5
/
8
3
/
4
1
1
1
/
4
1
3
/
8
50
1
1
/
4
1
5
/
8
2
2
3
/
8
2
3
/
4
75
1
3
/
4
2
3
/
8
3
3
1
/
2
4
1
/
8
100
2
3
/
8
3
1
/
8
4
4
3
/
4
5
1
/
2
125
3
4
5
6
7
150
3
5
/
8
4
3
/
4
6
7
1
/
8
8
1
/
4
Add 30°F to
temperature
change for direct
sunlight exposure.
Setting Position of Piston
If an expansion joint was installed completely closed with the piston bottomed on a cool day, there
would be no travel available when the conduit warmed up and expanded. If it was installed in a
maximum open position on a hot day, the expansion joint would pull apart when cooled. Thus, “setting”
the expansion joint is very important.
In addition to the proper number and sizes of expansion joints chosen, they must also be installed so
they can accommodate the expected length change. This requires proper “setting” of the expansion
joint. Most will be installed at a temperature halfway between maximum and minimum; for example,
installation at 65°F with an anticipated maximum temperature of 125°F and a minimum of 5°F. In this
case, the expansion joint would be installed or set with the inner piston halfway out. Expansion joints
are marked with a mid-point ring. If it was a colder day, for example 35°F with the same expected
temperature change range, the inner piston would be set with
3
/
4
of its maximum travel out. If the
temperature was hot (95°F), it would be set with the inner piston only
1
/
4
way out.
Solvent weld
Mid-point ring
Piston opening
Pipe strap
should be anchored
tightly to barrel
Pipe strap
mounted loosely
to allow movement
Solvent weld
Gross Automation (877) 268-3700 · www.carlonsales.com · [email protected]