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Drive Selection
1.
Determine side or bottom supply duct Application.
2.
Determine desired airflow.
3.
Calculate or measure the amount of external static pressure.
• Add or deduct any additional static resistance from "Additional Static Resistance Table".
4.
Using the operating point determined from steps 1, 2 & 3, locate this point on the appropriate supply air blower performance
table. (Linear interpolation may be necessary.)
5.
Noting the RPM and BHP from step 4, locate the appropriate motor and, or drive.
6.
Review the BHP compared to the motor options available. Select the appropriate motor and, or drive.
7.
Review the RPM range for the motor options available. Select the appropriate drive if multiple drives are available for the
chosen motor.
8.
Determine turns open to obtain the desired operation point.
Example
1.
2400 CFM
2.
1.6 IWC
3.
Using the supply air blower performance table below, the following data point was located: 1230 RPM & 1.62 BHP.
4.
Using the RPM selection table below, Size X and Model Y is found.
5.
1.62 BHP exceeds the maximum continuous BHP rating of the 1.5 HP motor. The 2 HP motor is required.
6.
1230 RPM is within the range of the 2 HP drives.
7.
Using the 2 HP motor and drive, .5 turns open will achieve 1230 RPM.
Example Supply Air Blower Performance
Air Flow
0.2
(CFM)
RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP
1.5 HP & Field Supplied Drive
2100
759
0.65
819
2200
778
0.73
838
2300
797
0.81
857
2400
817
1.90
877
Example RPM Selection
Size
Airflow
Model
(Tons)
Option
Std.
X
Y
H. Static
Example Additional Static Resistance
Size
Model
CFM Cooling Only
(Tons)
900
1000
X
Y
1100
1200
1300
Johnson Controls Ducted Systems
Available External Static Pressure - IWG
0.4
0.6
0.8
0.77
881
0.87
943
0.84
900
1.95
962
0.92
919
1.03
981
1.01
939
1.12
1002
Max
Motor
HP
BHP
Sheave
Sheave
1.5
1.73
1VM50
2
2.30
1VM50
Economizer
0.05
-0.05
0.05
-0.03
0.04
-0.02
0.04
0.00
0.03
0.01
1.0
1.2
Standard 1.5 HP & Drive
0.98
1005
1.08
1065
1.18
1.05
1024
1.15
1083
1.25
1.13
1043
1.23
1103
1.33
1.22
1063
1.32
1123
1.42
Blower
6 Turns
5 Turns
Open
Open
AK74
N/A
897
AK64
N/A
1039
4" Pleated Filter
3
0.01
0.00
0.02
0.00
0.03
0.01
0.04
0.01
0.05
0.01
1.4
1.6
Hi Static 2 HP & Drive
1121
1.28
1172
1.38
1217
1139
1.35
1191
1.45
1236
1159
1.43
1210
1.53
1255
1179
1.52
1230
1.62
1275
4 Turns
3 Turns
2 Turns
Open
Open
Open
945
991
1035
1094
1150
1207
Electric Heat kW
6
9
15
0.00
0.00
0.01
0.00
0.00
0.02
0.01
0.01
0.02
0.01
0.01
0.02
0.01
0.01
0.03
5566228-BIM-A-0818
1.8
2.0
1.48
1254
1.59
1.56
1273
1.66
1.64
1292
1.74
1.73
1312
1.83
1 Turn
Fully
Open
Closed
1079
1126
1256
1308
20
24
0.01
0.01
0.02
0.02
0.02
0.02
0.02
0.02
0.03
0.03
39
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