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A. DUCT FRICTION LOSS - TABLES & CHARTS

A. DUCT FRICTION LOSS - TABLES & CHARTS

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DUCT DESIGN TABLES AND CHARTS

B

Figure 14-4 Correction Factor for Unextended Flexible Duct
Table 14-7 Velocities/Velocity Pressures (Metric Units)
Table 14-8 Angular Conversion
Loss Coefficients for Straight-Through Flow
Table 14-9
Figure 14-5 Air Density Friction Loss Correction Factors

14.16
14.17
14.17
14.18
14.18

FITTING LOSS COEFFICIENT TABLES

14.19

Loss Coefficients, Elbows

14.19

A.
B.
C.
D.
E.
F
G.
H.
I.
J.

Elbow, Smooth Radius (Die Stamped), Round
Elbow, Round, 3 to 5 pc-90°
Elbow, Round, Mitered
Elbow, Rectangular, Mitered
Elbow, Rectangular, Mitered with Converging or Diverging Flow
Elbow, Rectangular, Smooth Radius without Vanes
Elbow, Rectangular, Smooth Radius with Splitter Vanes
Elbow, Rectangular, Mitered with Turning Vanes
Elbows, 90°, Rectangular, Z-Shaped
Elbows, 90°, Rectangular in Different Planes

14.19
14.19
14.19
14.20
14.20
14.20
14.21
14.22
14.22
14.23

K.
L.

Elbows, 30°, Round, Offset
Elbows, 90°, Rectangular Wye or Tee Shape

14.23
14.23

Table 14-11
A.
B.
C.
D.
E.
F
G.
H.
I.
J.

Loss Coefficients, Transitions (Diverging Flow)
Transition, Round, Conical
Transition, Rectangular, Pyramidal
Transition, Round to Rectangular
Transition, Rectangular to Round
Transition, Rectangular, Sides Straight
Transition, Symmetric at Fan with Duct Sides Straight
Transition, Asymmetric at Fan with Duct Sides Straight, Top Level
Transition, Asymmetric at Fan with Duct Sides Straight, Top 10° Down
Transition, Asymmetric at Fan with Duct Sides Straight, Top 10° Up
Transition, Pyramidal at Fan with Duct

14.24
14.24
14.24
14.25
14.25
14.25
14.25
14.26
14.26
14.26
14.26

Table 14-12
A.
B.
C.

Loss Coefficients, Transitions (Converging Flow)
Contraction, Round and Rectangular, Gradual to Abrupt
Contraction, Conical, Round and Rectangular
Contraction, Rectangular Slot to Round

14.27
14.27
14.27
14.28

Table 14-13
A.

Loss Coefficients, Converging Junctions (Tees, Wyes)
Converging Wye, Round

14.28
14.28

B.

Converging Tee, 90°, Round

14.29

C.
D.
E.
F
G.
H.
I.

Converging Tee, Round Branch to Rectangular Main
Converging Tee, Rectangular, Main and Branch
Converging Wye, Conical, Round
Converging Tee, 45° Entry, Branch to Rectangular Main
Symmetrical Wye, Dovetail, Rectangular
Converging Wye, Rectangular
Wye, Rectangular and Round

14.29
14.29
14.30
14.30
14.31
14.32
14.32

Table 14-10

Table 14-14

14.2

Loss Coefficients, Diverging Junctions (Tees, Wyes)

14.33

A.

Tee or Wye, 30° to 90°, Round

14.33

B.

90° Conical Tee, Round

14.34

C.
D.

45° Conical Wye, Round
90° Tee, Round, Rolled 45° with 45° Elbow, Branch 90° to Main

14.34
14.34

CHAPTER 14

E.
E
G.
H.
I.
J.
K.
L.
M.
N.

90° Tee, Round, Rolled 90° Tee, Round, Rolled 90° with 90° Elbow, Branch 90° to Main
90° Tee, Round, Rolled 45° with 60° Elbow, Branch 45° to Main
90° Conical Tee, Round, Rolled 45° with 45° Elbow, Branch 90° to Main
90° Conical Tee, Round, Rolled 45° with 60° Elbow, Branch 45° to Main
45° Wye, Round, Rolled 45° with 60° Elbow, Branch 90° to Main
45° Conical Wye, Round, Rolled 45° with 60° Elbow, Branch 90° to main
45° Wye, Round, Rolled 45° with 30° Elbow, Branch 45° to Main
45° Conical Wye, Round, Rolled 45° with 30° Elbow, Branch 45° to Main
45° Wye, Conical Main and Branch with 45° Elbow, Branch 90° to Main
Tee, 45° Entry, Rectangular Main and Branch

14.34
14.35
14.35
14.35
14.35
14.36
14.36
14.36
14.37
14.37

P
Q.
R.
S.
T.
U.
V.
W.
X.
Y
Z.

Tee, 45° Entry, Rectangular Main and Branch with Damper
Tee, Rectangular Main and Branch
Tee, Rectangular Main and Branch with Damper
Tee, Rectangular Main and Branch with Extractor
Tee, Rectangular Main to Round Branch
Wye, Rectangular
Tee, Rectangular Main to Conical Branch
Wye, Rectangular
Symmetrical Wye, Dovetail, Rectangular
Wye, Rectangular and Round
Tee, Rectangular Reducing, 45° Entry Branch

14.37
14.38
14.38
14.38
14.39
14.39
14.40
14.40
14.40
14.41
14.41

Loss Coefficients, Entries
Duct Mounted in Wall, Round and Rectangular
Smooth Converging Bellmouth, Round, without End Wall
Smooth Converging Bellmouth, Round, with End Wall
Conical, Converging Bellmouth, Round and Rectangular without End Wall
Conical, Converging Bellmouth, Round and Rectangular, with End Wall
Intake Hood
Hood, Tapered, Flanged or Unflanged
Hood, Canopy Island or Range
Hood, Slot (Dishwasher)

14.41
14.41
14.42
14.42
14.42
14.43
14.43
14.43
14.44
14.44

Loss Coefficients, Exits
Exhaust Hood
Exit, Conical, Round, with or without a Wall
Exit, Plane Diffuser, Rectangular, with or without a Wall
Exit, Pyramidal Diffuser, Rectangular, with or without a Wall
Exit, Discharge to Atmosphere form a 90° Elbow, Round and Rectangular
Exit, Duct Flush with Wall, Flow along Wall
Plane Asymmetric Diffuser at Fan Outlet without Ductwork
Pyramidal Diffuser at Fan Outlet without Ductwork
Fan, Free Discharge, Plenum
Exit, Abrupt, Round and Rectangular, with or without a Wall

14.44
14.44
14.45
14.45
14.45
14.46
14.46
14.47
14.47
14.47
14.47

Table 14-17
A.
B.

Loss Coefficients, Screens and Plates
Screen in Duct, Round and Rectangular
Perforated Plate in Duct, Thick, Round and Rectangular

14.48
14.48
14.48

Table 14-18
A.
B.
C.
D.
E.

Loss Coefficients, Obstructions (Constant Velocities)
Damper, Butterfly, Thin Plate, Round
Damper, Butterfly, Thin Plate, Rectangular
Damper Gate, Round
Damper Gate, Rectangular
Damper, Rectangular, Parallel Blades

14.49
14.49
14.49
14.49
14.50
14.50

Table 14-15
A.
B.
C.
D.
E.
F.

G.
H.
I.
Table 14-16
A.
B.
C.
D.
E.
F.

G.
H.
I.
J.

14.3

DUCT

F.
G.
H.
I.
J.
K.
L.

C

DESIGN

TABLES

Damper, Rectangular, Opposed Blades
Damper, Butterfly, Airfoil Blade, Rectangular
Obstruction, Smooth Cylinder in Round and Rectangular Ducts
Round Duct, Depressed to Avoid an Obstruction
Rectangular Duct, Depressed to Avoid an Obstruction
Rectangular Duct with 4-45° Smooth Radius Ells to Avoid an Obstruction
Rectangular Duct with 4-90° mitered Ells to Avoid an Obstruction

14.53

Duct Heat Transfer Coefficients (U.S. Units)

14.53

Figure 14-7

Duct Heat Transfer Coefficients (Metric Units)

14.53

Table
Table
Table
Table
Table
Table
Table

14-20
14-21
14-22
14-23
14-24
14-25
14-26

Air Equations
Fan Equations
Pump Equations
Hydronic Equivalents
Hydronic Equations
Converting Pressure in Inches of Mercury to Feet of Water
Electric Equations
Air Density Correction Factors

E HVAC EQUATIONS (METRIC UNITS)
Table
Table
Table
Table
Table
Table

14.4

14.50
14.51
14.51
14.51
14.52
14.52
14.52

HEAT TRANSFER COEFFICIENTS

Table 14-19

G

CHARTS

Figure 14-6

D HVAC EQUATIONS (U.S. UNITS)

F

AND

14-27
14-28
14-29
14-30
14-31
14-32

Air Equations
Fan Equations
Pump Equations
Hydronic Equations
Electric Equations
Air Density Correction Factors

14.54

14.54
14.55
14.55
14.55
14.56
14.56
14.57
14.57
14.58
14.58
14.59
14.59
14.60
14.61
14.61

METRIC UNITS AND EQUIVALENTS

14.62

Table 14-33

Metric Units (Basic and Derived)

14.62

Table 14-34

Metric Equivalents

14.63

DUCT SOUND DESIGN TABLES

14.65

Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table

14.65
14.66
14.66
14.68
14.68
14.68
14.69
14.69
14.69
14.70
14.70
14.70
14.71
14.71
14.71
14.72
14.72

14-35
14-36
14-37
14-38
14-39
14-40
14-41
14-42
14-43
14-44
14-45
14-46
14-47
14-48
14-49
14-50
14-51

Recommended NC-RC Levels for Different Indoor Activity Areas
Listening Conditions and Telephone Use as a Function of NC-RC Levels
Sound Sources, Transmission Paths, and Recommended Noise Reduction Methods
Specific Sound Power Levels, Kw, for Fan Total Sound Power
Blade Frequency Increments (BFI)
Correction Factor, C, for Off-Peak Operation
TLout vs. Frequency for Various Rectangular Ducts
TLinvs. Frequency for Various Rectangular Ducts
Experimentally Measured TLout vs. Frequency for Round Ducts
Calculated TL,,, vs. Frequency for Round Ducts
Experimentally Determined TL,, vs. Frequency for Round Ducts
Calculated TL,, vs. Frequency for Round Ducts
TLout vs. Frequency for Various Flat-Oval Ducts
TLin vs. Frequency for Various Flat-Oval Duct
Absorption Coefficients for Selected Plenum Materials
Sound Attenuation in Unlined Rectangular Sheet Metal Ducts
Coefficients for Equation 11-102 in Chapter 11

CHAPTER 14

Table 14-52
Table 14-53
Table 14-54
Table 14-55
Table 14-56
Table 14-57
Table 14-58
Table 14-59
Table 14-60
Table 14-61
Table 14-62
Table 14-63
Table 14-64
Table 14-65
Table 14-66
Table 14-67
Table 14-68
Table 14-69
Table 14-70
Table 14-71
Table 14-72
Table 14-73

Insertion Loss for Rectangular Ducts with 1" of Fiberglass Lining
Insertion Loss for Rectangular Ducts with 2" of Fiberglass Lining
Sound Attenuation in Straight Round Ducts
Constants for Use in Equation 11-104 in Chapter 11
Insertion Loss for Acoustically Lined Round Ducts-1 Inch Lining
Insertion Loss for Acoustically Lined Round Ducts-2 Inch Lining
Insertion Loss for Acoustically Lined Round Ducts-3 Inch Lining
Insertion Loss of Unlined and Lined Square Elbows Without Turning Vanes
Insertion Loss of Round Elbows
Insertion Loss of Unlined and Lined Square Elbows with Turning Vanes
7 Foot, Rectangular, Standard Pressure Drop Duct Silencers
7 Foot, Rectangular, Low Pressure Drop Duct Silencers
Round, High Pressure Drop Duct Silencers
Round, Low Pressure Drop Duct Silencers
Coefficients for Determining Static Pressure Drop Across Duct Silencers
Coefficient for System Component Effect on Duct Silencers
Transmission Loss Values for Ceiling Materials
Correction Coefficient " "for Different Types of Ceilings
Average Sound Absorption Coefficients, o,for Typical Receiving Rooms
Air Absorption Coefficients
Decibel Equivalents of Numbers (N)
Five-place Logarithms

14.72
14.73
14.74
14.75
14.75
14.76
14.77
14.77
14.78
14.78
14.78
14.79
14.79
14.80
14.80
14.81
14.81
14.82
14.82
14.83
14.83
14.84

14.5

14.6

DUCT

DESIGN

TABLES

A
DUCT FRICTION LOSS
TABLES AND CHARTS
AND

CHARTS

CHAPTER 14

14.7

DUCT

DESIGN

TABLES

AND

CHARTS

Table 14-1 DUCT MATERIAL ROUGHNESS FACTORS

Duct Material
Uncoated carbon steel, clean (Moody 1944)
(0.00015 ft) (0.05 mm)

Roughness
Category

Absolute
Roughness E,
mm
ft

Smooth

0.0001

0.03

Medium
Smooth

0.0003

0.09

PVC plastic pipe (Swim 1982)
(0.0003 to 0.00015 ft) (0.01 to 0.05 mm)
Aluminum (Hutchinson 1953)
(0.00015 to 0.0002 ft) (0.04 to 0.06 mm)

Galvanized steel, longitudinal seams, 4 ft
(1200 mm) joints (Griggs 1987)
(0.00016 to 0.00032 ft) (0.05 to 0.1 mm)
Galvanized steel, spiral seam with 1, 2, and 3
ribs, 12 ft (3600 mm) joints
(Jones 1979, Griggs 1987)
(0.00018 to 0.00038 ft) (0.05 to 0.12 mm)

(New Duct Friction Loss Chart)

Hot-dipped galvanized steel, longitudinal seams,
2.5 ft
(760 mm) joints (Wright 1945)
(0.0005 ft) (0.15 mm)

Old
Average

0.0005

0.15

Fibrous glass duct, rigid

Medium
rough

0.003

0.9

0.01

3.0

Fibrous glass duct liner, air side with facing
material (Swim 1978)
(0.005 ft) (1.5 mm)
Fibrous glass duct liner, air side spray coated
(Swim 1978)
(0.015 ft) (4.5 mm)
Flexible duct, metallic,
(0.004 to 0.007 ft (1.2 to 2.1 mm) when fully
extended)
Flexible duct, all types of fabric and wire
(0.0035 to 0.015 ft (1.0 to 4.6 mm)
when fully extended)
Concrete (Moody 1944)
(0.001 to 0.01 ft) (0.3 to 3.0 mm)

14.8

Rough

CHAPTER 14

Figure 14-3 DUCT FRICTION LOSS CORRECTION FACTORS

14.9

DUCT

DESIGN

TABLES

Table 14-2 CIRCULAR EQUIVALENTS OF RECTANGULAR DUCTS FOR
EQUAL FRICTION AND CAPACITY (U.S. Units) (2)
Dimensions in Inches

14.10

AND

CHARTS

CHAPTER 14

Cont. Table 14-2 CIRCULAR EQUIVALENTS OF RECTANGULAR DUCTS FOR
EQUAL FRICTION AND CAPACITY (U.S. Units) (2)
Dimensions in Inches

Equation for Circular Equivalent of a Rectangular Duct:
De = 1.30 [(ab)0.625/(a + b)0.250]

where
a = length of one side of rectangular duct, inches.
b = length of adjacent side of rectangular duct, inches.
De = circular equivalent of rectangular duct for equal friction and capacity, inches.

14.11

DUCT

DESIGN

TABLES

AND

Table 14-3 CIRCULAR EQUIVALENTS OF RECTANGULAR DUCTS FOR
EQUAL FRICTION AND CAPACITY (Metric Units) (2)
Dimensions in mm

14.12

CHARTS