9
In order to compensate for the expansion of the tubing, it is
necessary to estimate the amount of expansion and then
provide offsets or loops in the refrigerant piping. Normally the
area to be most concerned with is the straight line distance
from the fixture to the parallel compressor unit.
A simple form of expansion loop can be made of soft
tempered copper tube by bending it to the correct size and
shape. A neater type is made by assembling hard tube with
solder elbows as in Figure 9. The correct proportions of such
expansion loops to meet various conditions are shown in
Table 1.
In compensating for expansion and contraction, two items are
very important.
• Liquid and suction lines can not be joined
together and should not touch at any point.
• Pipe hangers must be located and installed in
such a manner as not to restrict the
expansion and contraction of the tubing. All
tubing clamps should have an insulating
material (i.e. Hydra Sorb bushing) to prevent
metal to metal contact.
Expansion Loops
Suction, liquid and remote condenser lines are subject to
expansion and contraction and proper piping techniques must
be employed (especially on hot gas lines) to prevent line
breakage. This is critical on long straight runs of generally
70’ or more where expansion loops must be provided and
hangers should allow for longitudinal movement of the piping.
On a refrigeration system with gas defrost, the refrigerant
lines expand and contract with temperature changes. The
suction line normally has the greatest movement since it has
the largest temperature change during defrost. If the
expansion and contraction is not planned for during the
installation of refrigeration lines, kinking and breaking of the
lines could occur.
Figure 9. Offsets
Table 1. Expansion Chart
Table of Values for "L"
Ref. Line Amount of Expansion (Inches)
O.D. " 1/211
1/222
1/23456
7/810 15 19 22 25 27 30 34 38
11/811 16 20 24 27 29 33 38 42
13/811 17 21 26 29 32 36 42 47
15/812 18 23 28 31 35 39 46 51
21/814 20 25 31 34 38 44 51 57
25/816 22 27 32 37 42 47 56 62
NOTE: Calculations for expansion and contraction should be based on the average coefficient of expansion of copper
which is .0000094 per degree Fahrenheit between 77
°
F and 212
°
F. Example, the expansion for each 100 feet of
length of any size of tube heated from room temperature of 70
°
F to 170
°
F, a rise of 100
°
F, is:
100

°

F (rise

°

F) X 100 (linear feet) X 12 (inches) X.0000094 (coefficient) = 1.128 inches
(Reprinted from Copper & Brass Research Association)