Duct fitting pressure drop coefficients for
mitered, rectangular elbow
From ASHRAE (1989), with permission
The pressure drop coefficient is given by C = KRE · C'
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Re x 10-4 |
1 |
2 |
3 |
4 |
6 |
8 |
10 |
³ 14 |
KRE | 1.40 |
1.26 |
1.19 |
1.14 |
1.09 |
1.06 |
1.04 |
1.0 |
Values for C'
H/W | ||||||||||||
0.25 | 0.5 | 0.75 | 1.0 | 1.5 | 2.0 | 3.0 | 4.0 | 5.0 | 6.0 | 8.0 | ||
q, deg | 20 | 0.08 | 0.08 | 0.08 | 0.07 | 0.07 | 0.07 | 0.06 | 0.06 | 0.05 | 0.05 | 0.05 |
30 | 0.18 | 0.17 | 0.17 | 0.16 | 0.15 | 0.15 | 0.23 | 0.13 | 0.12 | 0.12 | 0.11 | |
45 | 0.38 | 0.37 | 0.36 | 0.34 | 0.33 | 0.31 | 0.28 | 0.27 | 0.26 | 0.25 | 0.24 | |
60 | 0.60 | 0.59 | 0.57 | 0.55 | 0.52 | 0.49 | 0.46 | 0.43 | 0.41 | 0.39 | 0.38 | |
75 | 0.89 | 0.87 | 0.84 | 0.81 | 0.77 | 0.73 | 0.67 | 0.63 | 0.61 | 0.58 | 0.57 | |
90 | 1.3 | 1.3 | 1.2 | 1.2 | 1.1 | 1.1 | 0.98 | 0.92 | 0.89 | 0.85 | 0.83 |