Mil-Spec for Compressed Air Quality

Q. We just completed a Nadcap audit, and all went well. However, there was this finding: “Observed: No procedure exists and no point-of-use inspection is being performed to verify the cleanliness of the compressed air supply used in chemical processing area.” Is there a procedure or mil-spec for doing this check so I can create a procedure? If we started using nitrogen, would this negate the need for this test?­ –R.Z.

A. I am not familiar with a specific standard for industrial compressed air quality. I did find a Mil-Spec (BB-A-1034) that specifies compressed air for breathing, but that may not be relevant for your needs. The ISO 8573 standard provides guidance as to the amount of contaminants allowed per cubic meter, based on about 10 quality or classes of compressed air as well as test methods for oil, water and other contaminants. As with many standards, it will be up to you or your equipment suppliers to provide requirements for your needs. I did find one suggestion that specified the following for paint spraying: Level 3 for particulate (maximum 5-micron particle size); Level 4 for water, which requires a maximum dewpoint of +7°C; and Level 3 for oil, which is a maximum of 1 mg/m³.