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Design of 3-WAY FLOW LOGIC
1. Model Selecting and Capacity Calculator
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Straight equivalent length of joints
1-6. Straight Equivalent Length of Joints
Design the tubing system by referring to the following table for the straight equivalent length of joints.
Straight Equivalent Length of Joints
Wide tubing size (mm)
12.7
15.88
19.05
22.22
25.4
28.58
31.8
38.1
90
°
elbow
0.3
0.35
0.42
0.48
0.52
0.57
0.7
0.79
45
°
elbow
0.23
0.26
0.32
0.36
0.39
0.43
0.53
0.59
U-shape tube bent (R60 100 mm)
0.9
1.05
1.26
1.44
1.56
1.71
2.1
2.37
Trap bend
2.3
2.8
3.2
3.8
4.3
4.7
5.0
5.8
Y-branch distribution joint
Equivalent length conversion not needed.
Ball valve for service
Equivalent length conversion not needed.
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Capacity loss caused by differences in tubing diameters
* Capacity loss will occur if a tubing system that matches the horsepower is not selected (for example, if a tubing
system was determined and installed with no plan for extension and extension occurs later). The loss rate can be
found from the graph below.
Cooling
Heating
95
96
97
98
99
100
Capacity ratio based on Suction and
Discharge tubes diameter (%)
Recommended Suction and Discharge tubes diameter (mm)
φ
19.05
φ
22.22
φ
22.22
φ
28.58
φ
28.58
φ
31.75
φ
31.75
φ
38.1
φ
25.4
φ
25.4
10
12
14
16
18
20
26
30
35
40
45
46
47
48
(Reading the graph)
<Example 1>
Currently a 20 HP system and
φ
28.58 Suction & Discharge tubings are used. Subsequently the system is expand-
ed, with 8 HP added to the same tubing system.
• Horsepower after extension: 20 + 8 = 28 HP
• From the graph above: Cooling: Capacity ratio is 96.7%. Actual capacity = 28
×
0.967 = 27.1 HP
Heating: Capacity ratio is 98.6%. Actual capacity = 28
×
0.986 = 27.6 HP
04-218 Airwell-2.qxp 01/06/2007 13:15 Page 9