Formula
Power ≈ 1% per 2 psi · unregulated flow ∝ (P₂ + 14.7) ÷ (P₁ + 14.7)Annual saving
$12,382
17.2% of the compressed-air bill, dropping 25 psi
Flow recovered
27cfm
Artificial demand removed
Power now / after
100 → 83kW
Where the money comes from
- Compressor works less per CFM (2 psi rule)
- $9,000
- Leaks and open blows pass less air
- $3,382
- Total annual
- $12,382
Unregulated demand is everything with no regulator downstream: leaks, open blow-offs, cabinet cooling, air motors, worn tools, and any drain stuck open. In a typical plant it is 25–40% of total flow — measure it by logging weekend or non-production flow.
Savings by target pressure
| Header | Drop | CFM recovered | $ / yr |
|---|---|---|---|
| 123 psig | −2 | 2 | $1,026 |
| 120 psig | −5 | 5 | $2,554 |
| 115 psig | −10 | 11 | $5,069 |
| 110 psig | −15 | 16 | $7,545 |
| 105 psig | −20 | 21 | $9,983 |
| 100 psig | −25 | 27 | $12,382 |
How to actually take the pressure down
- Find the real critical pressure — walk to the one machine that sets the setpoint and read the pressure at its inlet, not at the compressor.
- Fix the pressure drop between the compressor and that machine: separator ΔP, dryer, filters, undersized drops and quick-couplers.
- Add storage and a flow controller so the header can float lower without pressure dips during events.
- Lower the compressor setpoint in 2–3 psi steps, a week apart, and watch for complaints.
- Re-log flow after each step — the flow drop is the proof that artificial demand was real.
The 1% per 2 psi rule is a linearization around 100 psig and is accurate enough for 70–150 psig planning work. Below 70 psig or above 175 psig, use the actual CAGI curve for the package.
How to use this calculator
Quantify the extra air unregulated equipment consumes because the header runs higher than it needs to, and the energy recovered by lowering it.
- Enter the current header pressure and the lowest pressure your critical equipment truly requires.
- Enter total plant flow in CFM and the fraction of load that is unregulated open blowing, leaks and orifices.
- Read the artificial demand in CFM — the extra flow caused purely by the higher pressure.
- Read the combined savings: less flow to compress plus lower compressor specific power at the reduced setpoint.
- Verify pressure at the worst-case point of use before committing to a new setpoint.
Frequently asked questions
- What is artificial demand?
- Artificial demand is the additional air consumed by unregulated uses simply because the system pressure is higher than needed. Flow through an orifice or leak rises with absolute pressure, so every extra psi in the header is bought and blown away.
- How much can I save by lowering header pressure 10 psi?
- Typically 5% on compressor input power plus about 5–8% reduction in unregulated flow. In plants with significant leaks and open blowing, the combined effect is often 8–12% of total compressed air energy.
- How low can I safely set the header?
- Set it from the worst-case point of use, not the compressor room. Log pressure at the most demanding machine during peak production, add the pressure drop through its filter, regulator and hose, and keep a small margin — usually 5–10 psi — for transients.