Double-Width Centrifugal Fan Performance Supplement - Greenheck

STEP 1
Enter the performance table with the desired CFM
and Ps. Obtain the fan RPM, BHP and Class.
EXAMPLE
For this example, we will use 13,400 CFM at 2.0 Ps.
This gives us a fan RPM of 1847, requiring 10.9 BHP,
with Class I construction.
NOTE: If your specific fan selection requires inlet
vanes or if the fan operating point is not at standard air
(70°F), refer to the inlet vane and air density correction
factor graphs and tables found on pages 5 and 6.
D
)
0
0
1
x
a
P
(
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u
s
s
e
r
P
c
i
t
a
t
S
40
35
30
25
20
15
10
5
0
Class Max RPM
I 1960
II 2554
III 3219
)
g
w
.
n
i
(
e
r
u
s
s
e
r
P
c
i
t
a
t
S
18
16
14
12
10
8
6
4
2
BIDW-20
25 30
40
3
2
1½
1
DO NOT SELECT TO THE LEFT OF THIS SYSTEM CURVE
800
1100
1400
1700
0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
Inlet Sound Power, Lwi
RPM %WOV 1 2 3 4 5 6 7 8 L wi A
550 100 78 75 74 78 68 62 56 52 76
80 76 73 71 75 67 60 54 50 74
60 75 70 70 76 67 60 54 50 74
50 75 69 69 76 67 60 54 50 75
40 74 69 69 77 67 60 54 50 75
800 100 79 91 83 82 76 72 64 60 83
80 80 89 81 78 72 67 59 54 80
60 77 83 76 77 71 67 59 54 77
50 76 80 74 76 71 67 60 55 77
40 77 78 74 76 71 67 60 55 77
1100 100 85 92 91 89 85 81 74 70 90
80 84 88 88 87 81 77 69 65 87
60 83 84 83 83 79 76 70 65 85
50 80 83 82 83 79 76 70 66 84
40 80 83 82 83 78 75 70 66 84
1600 100 91 94 98 95 92 89 83 78 97
80 88 91 96 93 90 86 80 75 95
60 87 88 93 89 86 83 78 75 92
50 87 88 91 88 85 82 78 75 91
40 89 88 90 87 85 82 78 76 90
2200 100 98 100 103 105 98 96 91 88 105
80 95 97 100 103 96 92 87 84 102
60 92 93 98 99 93 91 87 84 100
50 93 93 98 97 93 90 87 84 99
40 95 95 98 98 92 90 88 86 99
3219 100 105 109 110 114 110 106 102 98 115
80 103 106 107 111 107 102 98 94 112
60 100 102 105 107 104 101 97 94 109
50 101 103 105 105 103 100 97 94 108
40 103 105 106 106 103 99 98 96 108
Step 3
E
20
15
10
7½
5
Volume (cfm x 1000)
0 5 10 15 20 25 30 35 40 45
3
Volume (m /hr x 1000)
The sound power level ratings shown are in decibels, referred to 10
23
-12 watts calculated per AMCA Standard 301. Values shown are for inlet Lwi, LwiA and outlet
Lwo, LwoA sound power levels for Installation Type B: free inlet, ducted outlet. Outlet ratings include the effects of duct end correction. The A-weighted sound
ratings shown have been calculated per AMCA International Standard 301.
50
1960
Step 2
2300
Fan Selection Procedure
50% WOV
2554
60
60% WOV
Sound Power [dB Ref 10 -12 watts]
2800
3000
F
3219
11
STEP 2
Enter the Fan Curve with the desired CFM and Ps.
Obtain the fan operating point, % WOV, Motor HP
and verify fan class by curve shading.
EXAMPLE
For this example, the fan operating point is at
85% WOV using a 15 HP motor.
70% WOV
RPM
BHP
% WOV
Density 0.075 lb/ft 3
Density 1.2 kg/m 3
80% WOV
90% WOV
20 BIDW
% WOV = (CFM X 100) / (RPM X 8.58)
Outlet Sound Power, Lwo
RPM %WOV 1 2 3 4 5 6 7 8 L wo A
550 100 90 78 75 68 67 59 52 47 73
80 90 77 71 64 64 54 47 45 70
60 83 74 68 63 62 54 48 45 67
50 82 73 67 63 63 54 48 45 67
40 82 73 67 63 63 54 48 46 67
800 100 93 96 83 77 77 71 63 57 84
80 90 92 81 73 72 64 57 52 80
60 87 84 76 72 69 63 57 53 75
50 87 82 74 72 68 62 57 54 74
40 89 83 73 71 68 62 57 54 74
1100 100 99 93 90 86 86 80 74 67 90
80 96 92 88 83 81 74 67 61 86
60 91 87 83 78 77 71 66 61 82
50 91 86 82 77 76 71 66 62 81
40 92 86 81 76 75 70 66 62 80
1600 100 105 98 98 94 93 89 85 77 98
80 102 95 96 91 92 87 81 73 96
60 100 91 93 87 87 83 77 72 92
50 100 92 92 86 86 81 76 72 91
40 100 93 92 85 84 81 76 72 90
2200 100 109 105 106 109 102 97 93 88 109
80 107 101 101 105 98 93 89 83 105
60 103 97 96 99 96 91 86 81 100
50 104 98 95 97 94 89 85 81 99
40 107 100 95 95 92 89 85 81 98
3219 100 117 115 113 118 114 108 104 99 118
80 115 112 109 113 110 104 100 94 114
60 111 108 105 107 106 102 97 92 110
50 112 109 104 105 104 100 96 92 108
40 116 112 106 103 102 99 95 92 107
®
STEP 3
Enter the Fan Sound Table
with the Fan RPM from the
performance table and the %
WOV from the fan curve. Obtain
the eight octave ratings for inlet
(Lwi) and Outlet (Lwo) Sound
Power.
EXAMPLE
For this example, the eight octave
ratings are circled in the table
below.
NOTE: The exact % WOV for your
desired performance can be found
using the equation at the top of
the Sound Power Tables if it is
not published. The eight octave
ratings can then be found using the
interpolation instructions found in
the Sound Performance section on
pages 8 and 9.
®