Leak Rate Estimator

System Information

Total system volume (ft³)

Initial pressure (psig)

Final pressure (psig)

Elapsed time (seconds)

Leak rate (scfm)

Instructions

The leak rate estimator is designed to estimate the total system leak rate of a compressed air system and can be used for similar compressed gas systems. The estimator uses the total system volume and a system pressure drop over time to calculate the volume of gas that is leaving the system over that time period.

Performing the test

• Ideally, no valid compressed air consumption will be taking place during the test so that only the leaks in the compressed air system will be measured. If it is not possible to shut off all compressed air usage, then each valid usage of air during the test must be identified and measured, so that it can be subtracted from the leak rate at the completion of the exercise.
• Calculate the total system volume of the compressed air system. This will include all storage tanks, headers and other piping. Small piping (less than 1" diameter) can generally be neglected, since the total volume of small piping is typically a small portion of the total system volume. Call the Clearinghouse if you need assistance estimating your total system volume.
• Locate or install a pressure gage, ideally near a receiving tank or large header. Record the system pressure at the start of the test.
• Valve out or completely shut down the air compressor and record the time.
• Wait for the system pressure to drop by a minimum of 10% from the starting pressure.
• Record the time and system pressure at the end of the test.
• Return the system to normal.

Inputs

• Total system volume - the volume of storage tanks, headers, and other piping.
• Initial pressure - the pressure of the system at the beginning of the test.
• Final pressure - the pressure of the system at the end of the test. Let the pressure drop by at least 10% for more accurate results.
• Elapsed time - the amount of time, in seconds, that it takes for the system to fall from the initial pressure to the final pressure. (End Time minus Start Time)

Outputs

• Leak rate - the rate at which compressed air is leaving the system during the test. This is an estimate of the rate at which compressed air leaves the system in the normal pressure range. This rate will contain all leaks, as well as all appropriate uses of compressed air during the test, so you should either ensure that all equipment is shut down during the test, or subtract any appropriate uses from the total.

Estimator assumes barometric pressure is 14.7 psia. To use a different value, enter here (psia)

Contact the Arkansas Industrial Energy Clearinghouse if you need assistance with this calculator.