5567611-BIM-B-1218
50
Johnson Controls Ducted Systems
Drive selection
1.
Determine side or bottom supply duct application.
2.
Determine desired airflow.
3.
Calculate or measure the amount of external static pressure.
4.
With the operating point determined from steps 1, 2, and 3, locate this point on the appropriate supply air blower performance
table. Linear interpolation may be necessary.
5.
Note the RPM and BHP from step 4 and 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 the 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 and 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 achieves 1230 RPM.
Example supply air blower performance
Air flow
(CFM)
Available external static pressure - IWG
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
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
Standard 1.5 HP & Drive
Hi Static 2 HP & Drive
2100
759
0.65
819
0.77
881
0.87
943
0.98
1005
1.08
1065
1.18
1121
1.28
1172
1.38
1217
1.48
1254
1.59
2200
778
0.73
838
0.84
900
1.95
962
1.05
1024
1.15
1083
1.25
1139
1.35
1191
1.45
1236
1.56
1273
1.66
2300
797
0.81
857
0.92
919
1.03
981
1.13
1043
1.23
1103
1.33
1159
1.43
1210
1.53
1255
1.64
1292
1.74
2400
817
1.90
877
1.01
939
1.12
1002
1.22
1063
1.32
1123
1.42
1179
1.52
1230
1.62
1275
1.73
1312
1.83
Table X: RPM selection
Size
(tons)
Model
HP
Max BHP
Motor
sheave
Blower
sheave
6 turns
open
5 turns
open
4 turns
open
3 turns
open
2 turns
open
1 turn
open
Fully
closed
X
Y
1.5
1.73
1VL40
AK61
N/A
787
847
908
968
1029
1089
2
2.30
1VP56
AK74
N/A
1035
1084
1134
1183
1232
1281
