Pneumatic cylinder air consumption calculator
Estimate how much free air a pneumatic cylinder consumes per minute: enter bore, stroke, cycles per minute and supply pressure, and read the flow to size the compressor and FRL.
Cylinder air consumption
Extension uses the full bore area; retraction subtracts the rod area from the chamber. Free air accounts for the compression ratio (P_gauge + 1.013) / 1.013 — at 6 bar gauge the actual consumption is roughly 7× the geometric volume.
Free-air flow is the number that sizes the compressor and FRL: add 30–50 % margin for the duty cycle and another 20 % for leaks as a rule of thumb. FRL size and air-dryer capacity should be based on the peak free-air flow. The rod chamber is assumed to exhaust to atmosphere on retraction.
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Frequently asked questions
How do you calculate the air consumption of a pneumatic cylinder?
The calculator works out the swept volume of each stroke — extension uses the full bore area π/4 × D², retraction subtracts the rod area π/4 × (D² − d²) — then multiplies by cycles per minute and by the compression ratio (P_gauge + 1.013) / 1.013 to give free air in L/min.
Why is air consumption roughly 7× the cylinder volume at 6 bar?
Free air is the volume at atmospheric pressure (1.013 bar absolute). At 6 bar gauge the compression ratio is (6 + 1.013) / 1.013, about 6.9, so the compressor must supply roughly 7 litres of free air for every litre of geometric cylinder volume per cycle.
What should I add to the calculated free-air flow when sizing a compressor?
The free-air flow figure is the base demand for compressor and FRL sizing. As a rule of thumb add 30–50 % margin for the duty cycle and another 20 % for leaks, and size the FRL and air dryer on the resulting peak free-air flow.
AO Ctrl provides this tool for reference only.