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44
Roof Downblast - Exhaust
Belt Drive
GB-
Performance certified is for installation type A: Free inlet, Free outlet. Power rating (BHP) does not include transmission losses. Performance ratings include the effects
of a birdscreen. The sound ratings shown are loudness values in hemispherical sones at 5 ft. (1.5 m) in a hemispherical free field calculated per AMCA Standard 301.
Values shown are for installation type A: free inlet hemispherical sone levels.
Performance certified is for installation type A: Free inlet, Free outlet. Power rating (BHP) does not include transmission losses. Performance ratings include the effects
of a birdscreen. The sound ratings shown are loudness values in hemispherical sones at 5 ft. (1.5 m) in a hemispherical free field calculated per AMCA Standard 301.
Values shown are for installation type A: free inlet hemispherical sone levels.
1
3
⁄4 (44)
Roof Downblast - Exhaust
Belt Drive
GB-480
Damper Size = 48 x 48 (1219 x 1219)
Roof Opening = 50 x 50 (1283 x 1283)
Shroud Thickness = 0.080 (2.0)
Motor Cover Thickness = 0.064 (1.6)
Curb Cap Thickness = 0.100 (2.5)
^Approximate Unit Weight = 623 lbs. (283 kg)
All dimensions in inches (millimeters). *May be greater depending on
motor. ^Weight shown is largest cataloged Open Drip-Proof motor.
D
O
N
O
T
S
E
L
E
C
T
T
O
T
H
E
L
E
F
T
O
F
T
H
I
S
S
Y
S
T
E
M
C
U
R
V
E
Static Pressure (in. wg)
Static Pressure (Pa)
Volume (cfm x 1000)
3
Volume (m /hr x 1000)
RPM (Belt)
HP
Density 0.075 lb/ft
3
Density 1.2 kg/m
3
73
3
⁄4
(1873)
11
1
⁄4 (286)
*47
1
⁄4
(1200)
58
(1473)
Motor
HP
Fan
RPM
Static Pressure in Inches wg
0 0.125 0.25 0.375 0.5 0.625 0.75 0.875 1 1.25
480
1/2 200
CFM
12020 10059 6529
BHP
0.51 0.55 0.48
Sones
7.3 6.6 7.3
3/4 225
CFM
13522 11811 9500
BHP
0.73 0.77 0.76
Sones
8.3 8.0 7.6
1 250
CFM
15025 13516 11662 8820
BHP
1.00 1.05 1.06 0.98
Sones
9.5 9.5 8.6 8.1
1
1
⁄2 285
CFM
17129 15830 14379 12517 9587
BHP
1.48 1.54 1.58 1.56 1.42
Sones
11.8 11.2 10.7 10.0 9.1
2 310
CFM
18631 17437 16135 14589 12656
BHP
1.90 1.97 2.02 2.02 1.97
Sones
14.0 13.0 12.2 12.0 11.5
3 360
CFM
21636 20608 19548 18385 17010 15420 13507
BHP
2.98 3.06 3.13 3.17 3.17 3.21 3.00
Sones
17.6 17.0 16.4 15.9 15.5 15.0 14.2
5
393
CFM
23619 22678 21736 20683 19605 18254 16764 15086
BHP
3.87 3.66 4.05 4.10 4.14 4.12 4.06 3.94
Sones
20 19.9 19.5 18.8 18.3 18.0 17.5 16.7
415
CFM
24942 24050 23158 22189 21181 20012 18733 17211 15486
BHP
4.56 4.65 4.75 4.81 4.85 4.86 4.84 4.74 4.58
Sones
22 22 22 21 21 20 20 19.1 18.1
425
CFM
25542 24672 23801 22868 21883 20799 19550 18156 16604
BHP
4.90 4.99 5.09 5.16 5.20 5.22 5.20 5.13 5.00
Sones
23 23 23 22 22 21 21 20 19.3
7
1
⁄2
455
CFM
27345 26532 25719 24886 23966 23046 21953 20786 19471 15870
BHP
6.01 6.11 6.22 6.31 6.36 6.41 6.41 6.38 6.30 5.85
Sones
27 27 27 26 26 25 25 24 24 21
485
CFM
29149 28386 27623 26860 26016 25153 24290 23201 22106 19517
BHP
7.28 7.39 7.50 7.61 7.67 7.72 7.78 7.75 7.73 7.49
Sones
31 31 31 31 30 29 29 28 28 26
MAXIMUM BHP AT A GIVEN RPM = (RPM/245)
3
MAXIMUM RPM = 485
TIP SPEED (ft/min) = RPM x 12.632
MAXIMUM MOTOR FRAME SIZE = 215T