KEVOS® MAKEOS · Pneumatics
Compressed-Air System Sizing
How big a compressor, receiver and main pipe does this plant need, and what do the leaks cost?
Sizing a compressed-air system from the average demand: compressor free-air delivery with leakage and growth allowances, theoretical compression power with an overall efficiency (the same method as the compressor power tool), receiver volume to cover a peak deficit within the pressure band, the main pipe bore that keeps the pressure drop within a limit (Darcy–Weisbach, as the air line tool), and the annual energy cost of leakage.
Open the calculatorRuns in your browser. No account needed.
How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Demand | ||
| Average demand of the users | m³/min FAD | Average free-air demand of all users together (after diversity). |
| Leakage allowance | % | Air lost to leaks, as a share of demand (often 20–30% in unsurveyed plants). |
| Future growth allowance | % | Allowance for future users. |
| Peak demand above compressor output | m³/min | Short-term demand above what the compressor supplies. |
| Duration of the peak | min | How long that peak lasts. |
| Pressure | ||
| Working pressure | bar g | Pressure needed at the users. |
| Receiver upper pressure | bar g | Pressure at which the compressor unloads. |
| Receiver lower pressure | bar g | Lowest acceptable receiver pressure. |
| Main pipe | ||
| Main pipe length (incl. fitting allowance) | m | Length of the main pipe run, plus an allowance for fittings. |
| Allowable pressure drop | bar | Largest pressure drop you accept along the main. |
| Air temperature | °C | Temperature of the air in the main. |
| Pipe roughness | mm | Pipe roughness. |
| Energy | ||
| Compressor overall efficiency | % | Overall efficiency relating theoretical adiabatic power to shaft power. |
| Running hours per year | h | Hours the system is pressurised each year. |
| Electricity price | $/kWh | Cost of electricity. |
Method and formulas
- Compressor FAD = Q × (1 + leak) × (1 + growth).
- Power = single-stage adiabatic k = 1.4 from 1.013 bar to (p₁ + 1.013) bar ÷ efficiency.
- Receiver V = deficit × time × 1.013 ÷ (p₁ − p₂).
- Main bore found so the Darcy–Weisbach drop with Colebrook friction at working pressure equals the limit.
- Leak cost = leak flow × specific power × hours × price.
- Example: 5 m³/min of demand needs a 6.9 m³/min compressor of about 47.156 kW, a 1,351 L receiver and a 50.922 mm main.
Limitations
- Single-stage power estimate; real compressors publish their own specific power.
- Pipe bore is the minimum internal bore; choose the next larger standard pipe.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Plan a compressor, receiver and ring main for a workshop
- Show the energy cost of leaks to justify a leak survey
- Check a plant after adding air users
Who it is for
- Plant engineers
- Compressed-air engineers
- Maintenance managers
What you get
- Compressor capacity and power
- Receiver volume
- Main pipe bore and leak cost
Interpreting the result
- Fixing leaks is usually the cheapest capacity increase available.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 3030–3037, 3421–3425. Topic reference; no source tables or recommended settings are reproduced.
WORKOS tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
