Compressed Air Audits
A compressed air audit identifies waste, inefficiency, and improvement opportunities. Learn what an audit covers, the data needed, and how to use the results.
What is a Compressed Air Audit?
A compressed air audit is a systematic assessment of your compressed air system: generation, distribution, treatment, and usage. The goal is to identify waste, quantify costs, and recommend improvements with payback analysis.
A professional audit typically includes: flow and pressure logging over 7 to 14 days, power consumption measurement, leak survey, assessment of compressor sequencing, and evaluation of air treatment equipment.
What an Audit Covers
- Supply side: Compressor capacity vs demand, compressor efficiency, sequencing logic, pressure settings, receiver sizing, unloading performance.
- Treatment: Dryer sizing and performance, filter condition, condensate management, dew point measurement.
- Distribution: Pipe sizing and pressure drop, leak survey and quantification, pressure profile across the system.
- Demand side: Actual air usage by equipment, inappropriate uses (cleaning, cooling), artificial demand (over-pressurisation), intermittent vs continuous demand.
- Energy: kWh consumption, specific energy (kWh per cubic metre), cost per year, peak vs average demand.
Key Metrics from an Audit
| Metric | Target | Typical Finding |
|---|---|---|
| Leakage rate | Below 10% | Most plants: 20 to 30% |
| Specific energy | 0.08 to 0.12 kWh/m3 | Often 0.15 to 0.20 kWh/m3 |
| Pressure drop (compressor to point of use) | Below 0.5 bar | Often 1 to 2 bar |
| Artificial demand (over-pressurisation) | 0 bar | Often 0.5 to 1 bar |
| Compressor utilisation | 70 to 90% of capacity | Often 30 to 50% (oversized) |
| Heat recovery | 70 to 90% of input energy | Usually 0% (wasted) |
Acting on Audit Results
- Fix leaks first. Highest ROI, lowest cost. Most audits show 20 to 30% leakage.
- Reduce system pressure. Every 1 bar reduction saves 7% in energy.
- Fix sequencing. Ensure the most efficient compressor combination is running.
- Eliminate inappropriate uses. Replace compressed air cleaning with blowers or brushes.
- Install VSD compressor for variable loads.
- Recover heat from compressors for space or water heating.
- Resize piping if pressure drop is excessive.
- Replace undersized or failed dryers.
Typical savings
A compressed air audit and improvement program typically saves 20 to 50% of compressed air energy costs. For a plant spending $100,000 per year on compressed air, that is $20,000 to $50,000 per year. Most improvements pay for themselves in 6 to 18 months.
Tip: Install permanent flow and power monitoring after the audit. You can't manage what you don't measure. Continuous monitoring catches new leaks, efficiency drift, and demand changes early. PlantLogica's sensor monitoring system can integrate this data with your maintenance program.