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56 | REFRIGERANT DESIGN
Single Zone W
all Mounted
Art Cool
™
Premier Engineering Manual
Selecting Field-Supplied Copper Tubing
REFRIGERANT PIPING DESIGN
Figure 15: Coiled Expansion Loops and Offsets.
Large Tubing U-bend (>3/4 in.)
Loop
Small Tubing U-bend (<3/4 in.)
R
L
R
L
L
Anticipated Linear
Expansion (LE) (inches)
Nominal Tube Size (OD) inches
1/4
3/8
1/2
3/4
1/2
R
1
6
7
8
9
L
2
38
44
50
59
1
R
1
9
10
11
13
L
2
54
63
70
83
1-1/2
R
1
11
12
14
16
L
2
66
77
86
101
2
R
1
12
14
16
19
L
2
77
89
99
117
2-1/2
R
1
14
16
18
21
L
2
86
99
111
131
3
R
1
15
17
19
23
L
2
94
109
122
143
3-1/2
R
1
16
19
21
25
L
2
102
117
131
155
4
R
1
17
20
22
26
L
2
109
126
140
166
1
R = Centerline Length of Pipe.
2
L = Centerline Minimum Radius (inches).
Table 31: Linear Thermal Expansion of Copper Tubing in Inches.
Physical Pipe Length:
Actual length of straight segment(s) of pipe.
Equivalent Pipe Length:
Actual length of pipe plus equivalent lengths of long radius elbows, Y-branches, and valves.
1. Draft a one-line diagram of the proposed piping system connecting outdoor unit to indoor units. Follow the pipe limitations listed on the
previous page.
2. Calculate the physical length of each pipe segment and note it on the drawing.
3. Calculate the equivalent pipe length of each pipe segment.
Using Elbows
Field-supplied elbows are allowed as long as they are long radius and designed
for use with R410A refrigerant. The designer should be cautious with the quantity
and size of fittings used, and must account for the additional pressure losses in
equivalent pipe length calculation. The equivalent pipe length of each elbow must
be added to each pipe segment. See the table for equivalent lengths.
Table 32: Radii of Coiled Expansion Loops and Developed Lengths of Expansion Offsets.
Definitions
Layout Procedure
Component
Size (Inches)
1/4 3/8 1/2 5/8 3/4
Long Radius Elbow (ft.)
0.5 0.6 0.7 0.8 1.2
Pipe
Length
1
Fluid Temperature °F
35° 40° 45° 50° 55° 60° 65° 70° 75° 80° 85° 90° 95° 100° 105° 110° 115° 120° 125° 130°
10
0.04 0.04 0.05 0.06 0.06 0.07 0.08 0.08 0.09 0.09 0.10 0.10 0.11 0.11 0.11 0.12 0.13 0.14 0.15 0.15
20
0.08 0.08 0.10 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.20 0.21 0.22 0.22 0.23 0.26 0.28 0.29 0.30
30
0.12 0.12 0.15 0.18 0.20 0.21 0.23 0.24 0.26 0.27 0.29 0.30 0.32 0.33 0.32 0.35 0.39 0.42 0.44 0.45
40
0.16 0.16 0.20 0.24 0.26 0.28 0.30 0.32 0.34 0.36 0.38 0.40 0.42 0.44 0.43 0.46 0.52 0.56 0.58 0.60
50
0.20 0.20 0.25 0.30 0.33 0.35 0.38 0.40 0.43 0.45 0.48 0.50 0.53 0.55 0.54 0.58 0.65 0.70 0.73 0.75
60
0.24 0.24 0.30 0.36 0.39 0.42 0.45 0.48 0.51 0.54 0.57 0.60 0.63 0.66 0.65 0.69 0.78 0.84 0.87 0.90
1
Pipe length baseline temperature = 0°F. "Expansion of Carbon, Copper and Stainless Steel Pipe,"
The Engineers' Toolbox
, www.engineeringtoolbox.com.
Table 33: Equivalent Piping Length for Piping Components.
