Pneumatic Circuit Calculator #
Calculate total air demand for multi-cylinder pneumatic circuits. Configure up to 4 cylinder groups with different bore, stroke, and cycle rates. Get total FAD consumption, required compressor size, valve/port sizing, and FRL unit recommendation. Supports metric and imperial units.
Circuit Configuration
Cylinder Groups
Advanced calculator
Add Groups 2–4 for multi-size cylinder banks. Group 1 stays in Quick calculator.
About This Calculator
This pneumatic circuit calculator supports both quick single-group estimates and advanced multi-group configuration with up to 4 cylinder groups, simultaneous use factor, and double/single-acting modes. It calculates total swept volume per cycle, converts to Free Air Delivery (FAD) using the absolute pressure ratio, applies simultaneous use factor for realistic peak demand, and recommends compressor size, valve port sizes, and FRL unit capacity. This is a planning-level estimator, not a dynamic simulation. Example: a 2 inch bore × 6 inch stroke double-acting cylinder (0.5 in rod) at 90 PSIG cycling 10 times per minute consumes about 1.5 SCFM FAD. Browse all pneumatic calculators including cylinder sizing and compressor sizing.
Results
Continue Your Calculation
After total circuit demand, size the compressor or calculate pipe pressure drop for your distribution system.
Pneumatic Cylinder Configuration Reference #
Standard cylinder bore sizes and typical applications. Use this as a starting point for selecting cylinder bore for your load and pressure requirements.
| Bore (mm) | Bore (inch) | Force @ 6 bar | Force @ 90 PSI | Typical Application |
|---|---|---|---|---|
| 16 | 5/8 | 120 N | 28 lb | Clamping, small gates |
| 32 | 1-1/4 | 480 N | 110 lb | Conveyor diverters |
| 50 | 2 | 1178 N | 265 lb | Pressing, lifting |
| 80 | 3-1/8 | 3016 N | 678 lb | Heavy clamping |
| 100 | 4 | 4712 N | 1060 lb | Heavy lifting, pressing |
Circuit Demand Formulas #
Cylinder Air Consumption
V_extend = pi/4 x D^2 x S
V_retract = pi/4 x (D^2 - d^2) x S (double-acting)
FAD = (V_ext + V_ret) x cycles/min x (P_gauge + 14.7) / 14.7 / 1728
Total Circuit Demand
Total FAD = sum of all cylinder FAD values
Peak demand = Total FAD x simultaneous use factor (0.5-0.85)
Assumptions and Limitations
This is a planning-level estimator for steady-state air demand. It does not model transient effects, acceleration/deceleration, valve flow coefficients, or pressure dynamics. Actual peak demand may be higher during simultaneous cylinder starts. Compressor sizing should include 10-20% margin for leakage and future expansion. Always verify with component manufacturer datasheets. This result is not a substitute for professional engineering judgment or dynamic simulation.
Example Circuit Scenarios #
| Scenario | Cylinder mix | Peak FAD (approx.) | Next step |
|---|---|---|---|
| Small assembly cell | 4× 1.5″ bore @ 10 cpm | ~4–6 SCFM | Confirm with air consumption |
| Packaging line | 4× 1.5″ + 2× 2″ | ~12–20 SCFM | Size compressor |
| Heavy clamp bank | 6× 80 mm @ 6 cpm | ~25–40 SCFM | Size valve Cv |
Frequently Asked Questions #
How do you calculate total air demand for a pneumatic circuit?
Total air demand = sum of each cylinder's air consumption × simultaneous use factor. Each cylinder's consumption = (extend volume + retract volume) × cycles per minute × pressure ratio. Extend volume = π/4 × bore² × stroke. Retract volume = π/4 × (bore² - rod²) × stroke for double-acting. Pressure ratio converts compressed volume to FAD. Apply simultaneous use factor (0.5-0.85) because not all cylinders cycle simultaneously.
How do you size a valve for multiple cylinders?
Size the main supply valve (or manifold) for the total peak flow of all cylinders that could act simultaneously. Use the required Cv formula: Cv = Q × sqrt(G/ΔP) for the total flow at maximum allowable pressure drop (typically 5 PSI). For individual cylinder valves, size each for that cylinder's peak flow. A common rule: valve port size should match or exceed the cylinder port size. Use 1/4" valves for cylinders up to 40mm bore, 3/8" for 50-63mm, 1/2" for 80-100mm.
What simultaneous use factor should I use?
Use 0.5–0.65 for lightly sequenced machines, 0.7 as a common plant average, and 0.85–1.0 when many cylinders can fire together (transfer lines, press banks). If unsure, start at 0.7 and confirm with a peak-demand trend from a flow meter.
Related Tools
Related Guides
- Pneumatic Cylinder Sizing Guide — Force formula, bore selection, air consumption, and safety factors
- Pneumatic Cylinder Troubleshooting — Common faults, diagnosis steps, and fixes
- Pneumatic vs Hydraulic Actuators — Force density, speed, cost, and selection framework
- Compressed Air System Efficiency Guide — Leak detection, pressure optimization, and ROI