In his article "How to conduct compressed air audits on a budget," Ron Marshall from the Compressed Air Challenge encourages readers to take the initiative and conduct a budget-friendly DIY compressed air audit. The article explores eight key considerations when conducting the audit, including calculating baseline energy and cost.
Making a block diagram tells you what you have; the next items you need to calculate are how much energy the system is consuming and how much it's costing. The second step in the road to improvement involves creating a baseline, determining your energy consumption. This step involves taking basic electrical measurements or estimating the electrical consumption. In addition, annual operating hours need to be determined. For more accurate cost estimate results, you’ll also need a copy of your most recent electrical bill.
For most operating modes, it's fairly easy to get a rough idea of each compressor’s energy consumption. The tricky part is estimating how much compressed air flow each compressor is producing so you can estimate the supply system efficiency, expressed as specific power (kW per 100 cfm produced). The method of measurement depends on how accurate you want to be, with the highest accuracy costing the most money.
Measuring the compressor power consumption is best done using a three-phase kW meter. If measuring an air compressor for baselining without a kW meter there is a standard formula to use to estimate the power consumption from measured Amps and Volts:
A = average Amps of all three phases
V = average line-to-line voltage
PF = measured or estimated power factor (Power factor at full load can often be taken from the main compressor nameplate. If not known, use 0.85 at full load and 0.6 at in the unload position.)
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