251934-YTG-G-0708
66
Johnson Controls Unitary Products
Drive Selection
1.
Determine desired airflow.
2.
Calculate or measure the amount of external static pressure.
3.
Using the operating point determined from steps 1 & 2, locate this point on the appropriate supply air blower performance table.
(Linear interpolation may be necessary.)
4.
Noting the RPM and BHP from step 3, locate the appropriate model and drive on the RPM selection table.
5.
Review the BHP compared to the motor options available. Select the appropriate motor.
6.
Review the RPM range for the motor options available. Select the appropriate drive if multiple drives are available for the
chosen motor.
7.
Determine turns open to obtain the desired operation point.
Example
1.
19000 CFM
2.
5.4 iwg
3.
Using the supply air blower performance table below, the following data point was located: 1150 RPM & 36 BHP.
4.
Using the RPM selection table below, Size X and Model Y is found.
5.
36 BHP exceeds the maximum continuous BHP rating of the 30 HP motor. The 40 HP motor is required.
6.
1150 RPM is within the range of the 30 & 40 HP drives, but step 5 requires the 40 HP motor.
7.
Using the 40 HP motor and drive, 5.5 turns open will achieve 1150 RPM.
Example Supply Air Blower Performance
Air Flow
(CFM)
Available External Static Pressure - IWG
3.0
3.4
3.8
4.2
4.6
5.0
5.4
5.8
6.2
6.6
RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP
30 HP & Field Supplied Drive
Standard 30 HP & Drive
Alternate 40 HP & Drive
18000
800
10.00
850
14.00
900
18.00
950
22.00 1000 26.00 1050 30.00 1100
34.00 1150
38.00 1200
42.00
1250
46.00
19000
850
12.00
900
16.00
950
20.00
1000 24.00 1050 28.00 1100 32.00 1150
36.00 1200
40.00 1250
44.00
1300
48.00
20000
900
14.00
950
18.00
1000 22.00
1050 26.00 1100 30.00 1150 34.00 1200
38.00 1250
42.00 1300
46.00
1350
50.00
21000
950
16.00
1000
20.00
1050 24.00
1100 28.00 1150 32.00 1200 36.00 1250
40.00 1300
44.00 1350
48.00
1400
52.00
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
30
34.50
1VL51
BK99
1000
1025
1045
1060
1110
1150
N/A
40
46.00
1VL63
BK67
1125
1175
1250
1325
1400
1475
N/A
