Calculating Air Consumption at Different Inlet Pressures
METHOD 1
Air consumption is directly proportional to absolute inlet pressure | SCFM2 | | P2 + 1 atmosphere |
| = |
|
| SCFM1 | | P1 + 1 atmosphere |
|
| EXAMPLE: | A Model 3215 Vortex Tube consumes 15 SCFM at 100 PSIG (425 SLPM @ 6.9 Bar). To calculate the airflow with an inlet pressure of 80 PSIG (5.5 Bar), the calculation is as follows: |
| |
| English: | |
| | SCFM2 | | 80 PSIG + 14.7 |
| = |
| | 15 | | 100 PSIG + 14.7 | |
| |
| SCFM2 = 12.3845 |
|
| Metric: | |
| | SLPM2 | | 5.5158 Bar + 1.0135 |
| = |
| | 424.7527 | | 6.8948 Bar + 1.0135 | |
| |
| | SLPM2 | | 6.5293 |
| = |
| | 424.7527 | | 7.9083 | |
| |
| |
METHOD 2
Multiply the known flow by the ratio of the input pressures converted to absolute
STEP 1 Calculate the ratio of absolute inlet pressures
| (English) | | (Metric) |
| 80 PSIG + 14.7 | | | | 5.5158 Bar + 1.0135 | | |
| = | .8256 | | | = | .8256 |
| 100 PSIG + 14.7 | | | | 6.8948 Bar + 1.0135 | | |
STEP 2 Multiply known flow by the above ratio you just calculated
| (English) | | (Metric) |
| 15 SCFM x .8256 = 12.384 SCFM | | 4224.7527 SLPM x .8256 = 350.6869 SLPM |
THEREFORE
Model 3215 which consumes 15 SCFM @ 100 PSIG (425 SLPM @ 6.9 bar) will consume 12.4 SCFM @ 80 PSIG (351 SLPM @ 5.5 Bar).
| NOTE: | | To convert SCFM to SLPM multiply by the factor 28.3168 |
| | To convert PSIG to Bar multiply by the factor .0689 |