Determining the correct compressor size is a very complex issue that requires significant experience from compressed air technology specialists. However, the following procedure shows a basic approximate determination of the required compressor performance. The complete range of compressors in our e-shop can be found here.
STEP 1 - Instantaneous air consumption and duty cycle
The first step is to determine the instantaneous air consumption for the individual applications we intend to use. At the same time, it is necessary to know the so-called duty cycle (utilization factor), which is a general ratio of the time the connected device draws air to the total time including downtime. Basic applications and their parameters are listed in the following table:
| Equipment | Compressed air consumption (l/min) | Duty Cycle (Utilization factor) | |
|---|---|---|---|
| Production (continuous) | Maintenance (occasional) | ||
| Drill 10 mm | 500 | 0.2 | 0.1 |
| Angle grinder 125 mm | 900 | 0.2 | 0.2 |
| Angle grinder 160 mm | 1 600 | 0.1 | 0.1 |
| Polisher | 900 | 0.1 | 0.2 |
| Impact wrench 1/2" | 450 | 0.2 | 0.1 |
| Impact wrench 1" | 800 | 0.2 | 0.1 |
| Chipping hammer | 400 | 0.1 | 0.05 |
| Coating machine | 500 | 0.2 | 0.3 |
| Cleaning gun | 350 | 0.05 | 0.05 |
| Spray gun | 300 | 0.6 | 0.1 |
| Sandblasting gun 6 mm | 2 000 | 0.6 | 0.1 |
| Blow gun | 90 | 0.2 | 0.1 |
| Jackhammer (medium) | 3 840 | 0.3 | 0.2 |
STEP 2 - Determining total air consumption
Once we know the instantaneous consumption of individual devices and their duty cycle, we proceed as follows:
- Calculate average consumption (consumption × duty cycle)
- Determine the total consumption based on expected simultaneous use
- Add a margin for leaks and future needs
STEP 3 - Designing the compressor displacement (suction capacity)
To simplify the design, we provide a guideline table of the relationship between real consumption (free air delivery) and the required compressor suction capacity (l/min):
| Consumption (FAD l/min) | Required suction capacity (l/min) by drive type | ||
|---|---|---|---|
| DIRECT DRIVE | BELT (1st.) | BELT (2st.) | |
| 10 | 20 | 18 | 14 |
| 50 | 100 | 85 | 68 |
| 100 | 200 | 170 | 137 |
| 150 | 300 | 255 | 205 |
| 200 | 400 | 340 | 274 |
Calculation example:
Let's design a compressor for simultaneous use: 2× blow gun, 1× impact wrench 1/2", and 2× spray gun.
 |
2× blow gun (2x90x0.1) = 18 l/min Basic consumption: 123 l/min TARGET CONSUMPTION: 172 l/min |
For this consumption (172 l/min), we look for a suction capacity of approx. 570 l/min in the table (for belt drive). Read the full article on how to correctly choose a compressor here.