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45
Roof Downblast - Exhaust
Belt Drive
GB-500
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)
Damper Size = 54 x 54 (1371 x 1371)
Roof Opening = 56 x 56 (1435 x 1435)
Shroud Thickness = 0.100 (2.5)
Motor Cover Thickness = 0.064 (1.6)
Curb Cap Thickness = 0.100 (2.5)
^Approximate Unit Weight = 687 lbs. (312 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
83
(2108)
14
1
⁄2 (368)
*50
3
⁄4
(1289)
64
(1626)
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
500
1
175
CFM
14102 11123
BHP
0.50 0.57
Sones
6.7 6.5
200
CFM
16117 13588 10593
BHP
0.75 0.85 0.83
Sones
8.4 8.0 7.7
214
CFM
17245 14939 12242
BHP
0.92 1.04 1.04
Sones
9.5 9.1 8.7
1
1
⁄2 245
CFM
19743 17749 15481 12983
BHP
1.38 1.54 1.57 1.53
Sones
11.9 11.5 11.0 10.7
2 269
CFM
21677 19873 17857 15752
BHP
1.83 2.02 2.06 2.08
Sones
14.0 13.8 13.2 12.7
3 308
CFM
24820 23263 21627 19752 17903 15284
BHP
2.74 3.00 3.09 3.11 3.11 2.96
Sones
17.7 17.4 16.9 16.2 15.8 15.6
5
337
CFM
27157 25739 24253 22614 20937 19206 16671
BHP
3.59 3.89 4.01 4.06 4.08 4.06 3.88
Sones
19.9 19.5 19.1 18.5 17.9 17.6 17.4
366
CFM
29494 28188 26834 25429 23831 22310 20688 18366
BHP
4.60 4.92 5.10 5.20 5.20 5.24 5.19 4.99
Sones
22 22 21 21 20 19.8 19.5 19.4
7
1
⁄2 419
CFM
33764 32624 31467 30265 29015 27607 26276 24940 23486
BHP
6.90 7.27 7.57 7.70 7.80 7.80 7.84 7.88 7.78
Sones
27 27 27 26 26 25 24 24 23
10
440
CFM
35457 34371 33279 32134 30989 29679 28373 27107 25801 22407
BHP
8.00 8.38 8.74 8.87 9.01 9.03 9.05 9.10 9.09 8.73
Sones
30 29 29 29 29 28 27 26 26 25
460
CFM
37068 36030 34991 33900 32805 31625 30342 29127 27917 25310
BHP
9.14 9.54 9.94 10.10 10.24 10.32 10.32 10.36 10.41 10.26
Sones
32 32 32 32 32 31 30 29 28 27
MAXIMUM BHP AT A GIVEN RPM = (RPM/210)
3
MAXIMUM RPM = 460
TIP SPEED (ft/min) = RPM x 14.137
MAXIMUM MOTOR FRAME SIZE = 256T