The Real Cost of Compressed Air

Written By Stan Riddle, Technical Training Supervisor Acoem USA

Acoem USA has recently begun selling the SoundCam Ultra 3, an easy-to-use acoustic imager and video leak detector that can detect, measure, and display air and gas leaks, vacuum leaks, as well as partial electrical discharges, and includes infrared capabilities.

There are other tools available to detect air leaks, so what’s the big deal? A lot—if you know the true cost of air leaks. Fortunately, the SoundCam Ultra 3 can calculate the cost of a compressed air leak right on the screen!

Uncovering the True Cost of Compressed Air Leaks

Compressed air leaks in manufacturing, building controls, fire protection, and other areas can result in significant energy and financial losses. The U.S. Department of Energy has published the following formula to calculate the cost of a compressed air leak.

Cost ($) =

(bhp) x (0.746) x (# of operating hours) x ($cost/kWh) x (% run time) x (%full load bhp)

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Motor Efficiency

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• bhp =?brake horsepower, usually slightly higher than the motor nameplate horsepower rating
• 0.746 =?conversion between hp and kW
• # of operating hours = hours per year of run time
• $cost/kWh = cost of electrical power from your power company
• % run time = time the compressor is fully loaded
• % full load bhp

As an example:

• 00 hp air compressor (101 bhp)
• .746 is a constant
• Runs 8760 hours per year (6200 hr. loaded/2560 hr. unloaded)
• Cost per kWh (Often negotiated by a company, and we will assume $0.10/kWh)

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LOADED = (101 bhp) (.746) (6200 hr) ($.10k Wh) (.714 %loaded) (1.0 full load) = $33,354.17 per year

UNLOADED = (101 bhp) (.746) (2560 hr) ($.10kWh) (.20 %loaded) (.21 full load) = $810.12 per year

TOTAL = $34,164.29 per year for compressed air

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But –? that’s just the cost of making compressed air.

It does not include:

• Cost and depreciation of the air compressor
• Mechanical maintenance and spare parts
• Filtering the air coming in
• Cooling and drying compressed air
• Piping, valves, controls, regulators, moisture separators, etc

A decent estimate of the real cost of compressed air may be more like 1.5 times the electrical cost.

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Complex Leaks: SoundCam Ultra 3’s Solution

There are many formulas available to calculate the size of air leaks, but many are based on orifice diameters, like this chart published by the US Department of Energy. However, these formulas are designed for “round hole” orifice leaks. In many cases, leaks originate from threaded pipes, fittings, ball valves, cracked lines, and other sources that are not round holes, making the leak sizes much more challenging to calculate.

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The SoundCam Ultra 3 bases its calculations on sound pressure levels and cost per kWh. In the image below, a cost of $.20/kWh was input.

• ( $.14/kWh + a multiplier of 43% to include mechanical maintenance and associated costs)

This test was done with 140 psi compressed air blowing through a pipe cap with (2)-?” diameter holes drilled in the end.

The SoundCam Ultra 3 calculates this leak as:

• 98.1dB
• 75.7cfm
• A cost of $1194.08 per year

So, what does compressed air cost? A LOT!

And compressed air leaks are:

• Wasted energy
• Extra air compressor requirements
• Noise

If your company is not performing a compressed air leak preventative maintenance (PM) program, or if you are not capturing the true costs of compressed air leaks, we can help!