One or more stages
In a single-stage design, air reaches the final pressure in one compression stage. In a multistage machine, partially compressed air passes to the next stage, often through an intercooler. Dividing compression into stages and cooling affect both temperature and energy use. Cylinder count alone does not indicate the number of stages.
Air delivery and rest periods
Geometric intake displacement differs from delivered air at working pressure. Operating limits may require rest periods or restrict starts and ambient temperature. Industrial piston compressors also exist for demanding duty, so the same duty cycle cannot be prescribed for every piston compressor.
What to check in practice
- Check actual air delivery at the tool's operating pressure.
- Check the permitted running time and number of starts in the manual.
- Include the receiver, condensate drainage and air treatment in the complete system.
Example scenario
A tool uses 250 L/min while working and runs for 2 minutes out of every 10. Its time-averaged demand is 50 L/min, but the instantaneous supply must cover 250 L/min or draw the difference from the air receiver. The time needed to replenish the receiver must also be checked.
What to watch out for
- Comparing intake litres alone.
- Assuming a larger receiver allows unlimited continuous air demand.
- Exceeding the duty cycle because the receiver fills slowly.
Will replacing the pressure switch increase capacity?
No. The pressure switch changes when the compressor starts and stops, not its designed air delivery. Improperly increasing the cut-out pressure can exceed the limits of both compressor and receiver. Changes in demand should be addressed by reviewing the whole system design.