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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-540
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 = 748 lbs. (339 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 0.75 1 1.25 1.5 1.75
540
1
175
CFM
15488 1250
BHP
0.61 0.65
Sones
6.9 6.3
195
CFM
17258 14674 11068
BHP
0.85 0.90 0.87
Sones
7.8 7.5 7.2
205
CFM
18143 15724 12632
BHP
0.99 1.04 1.03
Sones
8.3 8.2 8.1
1
1
⁄2 235
CFM
20798 18814 16229 12673
BHP
1.49 1.57 1.56 1.50
Sones
10.1 10.4 10.5 10.6
2 259
CFM
22922 21228 18963 16439
BHP
1.99 2.09 2.11 2.08
Sones
12.3 12.1 11.9 11.6
3 296
CFM
26197 24874 22870 20831 18610
BHP
2.97 3.11 3.14 3.13 3.10
Sones
16.2 15.6 15.3 15.0 14.3
5 351
CFM
31064 30005 28492 26810 25115 21376
BHP
4.96 5.13 5.21 5.24 5.23 5.15
Sones
21 21 19.9 19.3 18.7 17.4
7
1
⁄2 402
CFM
35578 34653 33552 32075 30612 27519 24274
BHP
7.45 7.65 7.80 7.84 7.87 7.82 7.73
Sones
27 26 26 25 24 23 21
10 442
CFM
39118 38277 37435 36109 34766 32131 29134 26111
BHP
9.90 10.12 10.34 10.39 10.44 10.46 10.36 10.24
Sones
32 32 32 32 32 28 27 26
15
474
CFM
41950 41165 40381 39287 38034 35558 32927 30151 26271
BHP
12.21 12.45 12.68 12.80 12.85 12.90 12.84 12.73 12.42
Sones
36 36 37 36 35 33 31 30 28
505
CFM
44694 43957 43221 42332 41157 38813 36503 33869 31293 26758
BHP
14.77 15.02 15.27 15.45 15.51 15.60 15.60 15.48 15.36 14.84
Sones
40 40 40 40 39 38 36 35 32 30
MAXIMUM BHP AT A GIVEN RPM = (RPM/202)
3
MAXIMUM RPM = 505
TIP SPEED (ft/min) = RPM x 14.137
MAXIMUM MOTOR FRAME SIZE = 256T