Heatcraft Refrigeration Products H-IM-72A User Manual download pdf (Page 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. "

/2 11

/2 22

/2 3456

/8 10 15 19 22 25 27 30 34 38

/8 11 16 20 24 27 29 33 38 42

/8 11 17 21 26 29 32 36 42 47

/8 12 18 23 28 31 35 39 46 51

/8 14 20 25 31 34 38 44 51 57

/8 16 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)

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Heatcraft Refrigeration Products H-IM-72A User Manual Page 9

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