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.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 on the RPM selection table.
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
1.2600 CFM
2.1.6 iwg
3.Using the supply air blower performance table below, the following data point was located: 1268 RPM & 1.95 BHP.
4.Using the RPM selection table below, Size X and Model Y is found.
5.1.95 BHP exceeds the maximum continuous BHP rating of the 1.5 HP motor. The 2 HP motor is required.
6.1268 RPM is within the range of the 2 HP drives.
7.Using the 2 HP motor and drive, .5 turns open will achieve 1268 RPM.
Airflow Performance
Example Supply Air Blower Performance
Air Flow |
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| Available External Static Pressure - IWG |
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0.2 | 0.4 | 0.6 | 0.8 | 1.0 | 1.2 |
| 1.4 |
| 1.6 |
| 1.8 |
| 2.0 |
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(CFM) |
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RPM | BHP | RPM | BHP | RPM | BHP | RPM | BHP | RPM | BHP | RPM BHP | RPM BHP | RPM BHP | RPM BHP | RPM BHP | |||||||
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| 1.5 HP & Field | Supplied Drive |
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| Standard 1.5 HP & Drive |
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| Alternate 2 HP & Drive |
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2200 | 804 | 0.50 | 866 | 0.71 | 925 | 0.90 | 982 | 1.06 | 1038 | 1.21 | 1092 | 1.35 | 1147 | 1.48 | 1203 | 1.61 | 1259 | 1.73 | 1317 | 1.87 | |
2400 | 835 | 0.66 | 897 | 0.87 | 956 | 1.06 | 1013 | 1.22 | 1069 | 1.37 | 1124 | 1.51 | 1178 | 1.64 | 1234 | 1.77 | 1290 | 1.90 | 1348 | 2.03 | |
2600 | 869 | 0.84 | 931 | 1.05 | 990 | 1.24 | 1047 | 1.40 | 1103 | 1.55 | 1158 | 1.69 | 1212 | 1.82 | 1268 | 1.95 | 1324 | 2.07 | 1382 | 2.21 | |
2800 | 906 | 1.03 | 968 | 1.25 | 1027 | 1.43 | 1084 | 1.60 | 1139 | 1.75 | 1194 | 1.89 | 1249 | 2.02 | 1304 | 2.14 | 1361 | 2.27 | - | - | |
Table X: RPM Selection
Size | Model | HP | Max | Motor | Blower | 6 Turns | 5 Turns | 4 Turns | 3 Turns | 2 Turns | 1 Turn | Fully | |
(Tons) | BHP | Sheave | Sheave | Open | Open | Open | Open | Open | Open | Closed | |||
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X | Y | 1.5 | 1.73 | 1VM50 | AK74 | N/A | 897 | 945 | 991 | 1035 | 1079 | 1126 | |
2 | 2.30 | 1VM50 | AK64 | N/A | 1039 | 1094 | 1150 | 1207 | 1256 | 1308 | |||
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32 | Johnson Controls Unitary Products |
