Correction Factors for Altitudes above Sea Level

These factors can be used to obtain air flow rates applicable for your altitude when conditions are 70 deg. F., 65% Relative Humidity, and 30.00" Mercury.  

Use of this correction factor is mentioned in ASTM D737-96 - Note 5 - "For air permeability results obtained 600 m (2000 ft) above sea level, correction factors may be required."

To calculate a sea level corrected airflow result, multiply the airflow value that you obtain at your altitude by the Factor for your altitude.

Example: If you tested Sample #1 at Sea Level and got an airflow result of 34.7 CFM (10.3" on VM), then when you tested the same sample on the same tester at 4,000 ft Altitude you would get a reading of 32.2 CFM (8.9" on VM) -> 32.2 CFM x 1.077 = 34.7 CFM, and when the same sample tested on the same tester at 6,000 ft Altitude you would get a reading of 31.0 CFM (8.3" on VM) -> 31.0 CFM x 1.119 = 34.7 CFM.

To calculate a calibration chart for your instrument at your altitude, multiply the correction factor for your appropriate altitude by each of the table values in the sea level chart that was shipped with your instrument.

The Frazier 2000 Air Permeability Tester automatically incorporates altitude correction in results when location elevation is set in the software.