Heatcraft Refrigeration Products When Are Expansion Loops Required? Understanding Expansion Loops and Their Tables

Parallel Compressor Systems

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.

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

Figure 9. Offsets

Table 1. Expansion Chart

Table of Values for “L”

•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

Ref. Line				Amount of Expansion (in.)
OD (in.)	1/2	1	1-1/2	2	2-1/2	3	4	5	6
7/8	10	15	19	22	25	27	30	34	38
1-1/8	11	16	20	24	27	29	33	38	42
1-3/8	11	17	21	26	29	32	36	42	47
1-5/8	12	18	23	28	31	35	39	46	51
2-1/8	14	20	25	31	34	38	44	51	57
2-5/8	16	22	27	32	37	42	47	56	62

NOTES: 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)

Parallel Compressor Systems Installation & Operations Manual, October 2004 9