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43
Roof Downblast - Exhaust
Belt Drive
GB-420
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 = 42 x 42 (1067 x 1067)
Roof Opening = 44 x 44 (1130 x 1130)
Shroud Thickness = 0.080 (2.0)
Motor Cover Thickness = 0.064 (1.6)
Curb Cap Thickness = 0.100 (2.5)
^Approximate Unit Weight = 495 lbs. (225 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
65
1
⁄4
(1657)
9
3
⁄4 (248)
*44
(1118)
52
(1321)
Motor
HP
Fan
RPM
Static Pressure in Inches wg
0 0.125 0.25 0.375 0.50 0.625 0.75 1.00 1.25 1.5
420
1/2
200
CFM
8242 6454
BHP
0.27 0.29
Sones
3.1 2.9
240
CFM
9890 8573 6365
BHP
0.46 0.50 0.48
Sones
4.6 5.0 4.9
3/4 275
CFM
11332 10219 8698
BHP
0.69 0.75 0.76
Sones
6.2 6.8 5.6
1 305
CFM
12568 11579 10320 8672
BHP
0.95 1.01 1.03 1.01
Sones
8.0 8.4 7.5 7.2
1
1
⁄2 345
CFM
14217 13357 12411 11102 9463
BHP
1.37 1.45 1.49 1.50 1.45
Sones
11.7 11.3 10.8 10.1 9.6
2 380
CFM
15659 14892 14043 12983 11787 10108
BHP
1.83 1.92 1.97 2.00 2.00 1.91
Sones
14.4 13.8 13.3 12.7 12.3 12.0
3 435
CFM
17925 17264 16540 15792 14790 13764 12502
BHP
2.74 2.86 2.93 2.97 2.99 3.00 2.95
Sones
19.0 18.4 17.8 17.3 16.6 16.4 16.5
5
475
CFM
19574 18968 18320 17640 16887 15929 14994 12315
BHP
3.57 3.69 3.78 3.84 3.88 3.90 3.91 3.69
Sones
22 21 20 19.8 19.3 18.6 18.3 18.3
515
CFM
21222 20663 20081 19459 18826 18046 17162 15254 12312
BHP
4.55 4.68 4.80 4.87 4.92 4.95 4.98 4.92 4.56
Sones
24 24 23 22 21 21 20 19.4 19.1
7
1
⁄2
558
CFM
22994 22478 21957 21383 20805 20219 19446 17835 15908
BHP
5.79 5.93 6.07 6.15 6.22 6.28 6.31 6.34 6.21
Sones
27 27 26 25 24 24 23 23 22
600
CFM
24725 24245 23765 23243 22709 22166 21621 20104 18585 16590
BHP
7.20 7.35 7.51 7.61 7.70 7.76 7.81 7.87 7.86 7.64
Sones
30 30 30 29 27 27 26 26 26 26
MAXIMUM BHP AT A GIVEN RPM = (RPM/302)
3
MAXIMUM RPM = 600
TIP SPEED (ft/min) = RPM x 11.061
MAXIMUM MOTOR FRAME SIZE = 215T