Is the calculated force the available cylinder force?

No. It is ideal net pressure force before seal friction, side load, acceleration, gravity and other loads.

Can I enter normal litres per minute or SCFM?

No. Q/A needs actual volumetric flow at the powered chamber state and operating point, not standardized free-air flow.

Does ISO 15552 define this calculator formula?

No. ISO 15552:2018 establishes interchangeability dimensions for a specified cylinder family; the pressure-area and continuity equations are general engineering relations.

Why are both chamber pressures required?

Exhaust-side or opposing chamber pressure acts on the opposite effective area and changes net pressure force.

Pressure-area and actual-flow arithmetic — not cylinder sizing

Documented Pneumatic-Cylinder Pressure-Force Arithmetic

Compute ideal two-chamber pressure force from controlled piston geometry and measured cap/rod chamber gauge pressures. Optionally compute a geometric rate from actual local powered-chamber volumetric flow. No friction, safety factor, valve capacity or available-force/speed prediction is invented.

Two chamber pressuresSigned net forceActual flow onlyNo ISO formula claim

Ideal pressure force in selected direction

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Signed extension-axis pressure force

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Cap area Ab

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Rod-side annular area Aa

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Q/A geometric rate

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Ideal arithmetic only.

Ab=πD²/4; Aa=π(D²−d²)/4
Fext-axis=pc·Ab−pr·Aa; Fselected=Fext-axis (extend) or −Fext-axis (retract)
vgeom=Qactual/Apowered

D is controlled piston/bore diameter; d is rod diameter; pc and pr are cap- and rod-chamber gauge pressures referenced to the same ambient; positive Fext-axis acts toward extension. For Q/A, Apowered is Ab during extension or Aa during retraction.

These relations are general force balance and geometric continuity. They are not formulas specified by ISO 15552.

Theoretical only. Available force also depends on seal/bearing friction, breakaway, side load, acceleration, gravity, external load, cushioning, pressure dynamics and component condition. Actual speed also depends on compressibility/storage, leakage, valve/line conductance, upstream/downstream pressure, temperature, load and control method.

Critical flow basis

Normal/standard/free-air flow is referenced to a stated standard condition and cannot be divided directly by chamber area. Convert it to actual chamber volumetric flow using a documented gas-state model and the same operating point before using this worksheet. The old imperial conversion was also nearly 1,000 times too small: one exact international cubic foot per minute is 471,947.4432 mm³/s, not 473.176 mm³/s.

ISO 15552 scope

ISO 15552:2018, edition 2, published and confirmed 2025, establishes metric basic, mounting and accessory dimensions for interchangeability of detachable-mounting pneumatic cylinders, single or double rod, with/without magnetic-sensor provision, rated up to 1,000 kPa (10 bar), with bores from 32 to 320 mm. It does not establish universal friction percentages, safety factors, rod sizes, available force or speed for an arbitrary cylinder.

NEEDS_LICENSED_SOURCE: exact selected-cylinder dimensions/ratings, friction/breakaway data, cushioning/load limits, valve and tubing flow characteristics, standardized-flow reference conditions and sizing/acceptance rules. Use the current manufacturer datasheet and complete applicable standards.

Fuentes

ISO 15552:2018 official record; Festo/Lab-Volt pneumatic actuator training; SMC air-cylinder characteristics; NIST exact unit conversions.