What a 3 mm compressed air leak actually costs
A worked example: converting an audible leak into annual kWh, dollars, and the compressor horsepower it quietly reserves.
- Compressed air
- Worked example
Compressed air is the most expensive utility in most plants and the one nobody meters. The arithmetic that turns a hiss into a number is short enough to do on a clipboard, and it is usually enough to justify a leak survey on its own.
The chain of conversions
Leak orifice → free air delivered → compressor specific power → annual kWh → dollars. Each step has a defensible source, and each one is where a savings estimate gets challenged.
Leak flow scales with the square of the orifice diameter, which is why a survey that only chases the loud ones misses most of the money.
What to do with the number
Rank leaks by annual cost, not by how easy they are to hear. Then check whether fixing them lets the compressor unload or shut off — if the system stays in modulation, the kWh savings will land well under the calculation.
A leak repair program only pays if the control strategy can convert reduced demand into reduced power.
Write the assumption into the report. It is the first thing a utility reviewer will ask about.