INSTALLATION INSTRUCTIONS
PREFERREDFAIR (Standard)
POOR | NOT ACCEPTABLE |
Various Elbows Showing Radius Ratios
FIG. 2.3
E D D I E S |
|
ITEM 1 | ITEM 4 |
Sharp Angle | Long Radius Bend |
E D D I E S |
|
ITEM 2 | ITEM 5 |
Rounded | Splitters, or turning vanes |
Outer | installed in sharp angle |
Corner | bend |
R
D
RR = R
WW
Radius Ratio (RR)
or RR = 1.5
FIG. 2.4
R b
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| D |
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| R a | CR = R a |
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W |
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| R b |
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| Curve Ration (CR) |
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| Optimum Reading CR = .05 |
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| FIG. | 2.5 |
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| CR = | Ra |
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| Rb |
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| R1 | R1 = 2 Ra |
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| CR = .25 |
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R b | R a |
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| CR = | Ra |
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| Rb |
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| R1 | R1 = 2 Ra |
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| (Rb - R1) |
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| R2 = |
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R2 |
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| 2 | + Ra |
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R b |
| CR = .15 |
| |
R a
FIG. 2.6Using Splitters to reduce resistance.
| ITEM 6 |
ITEM 3 | Splitters in rounded |
Rounded | corner bend |
Corners |
|
FIG. 2.7
Different ways of making a 90 degree bend. Some
involve greater pressure losses than others.
LARGE DUCT | ABRUPT |
| |
| CONTRACTION |
E D D YSMALL
LOSSES D U C T
FIG. 2.8
Pressure losses occur with abrupt reducing fittings.
ABRUPT EXPAN-
S I O NLARGE D U C T
SMALL
D U C T
E D D Y
LOSSES
FIG. 2.9
Abrupt expansion results in excessive pressure losses.
6
