Use of an Image Analyzer and Statistical Analysis to Determine and Minimize Air Permeability Tester Error and the Establishment of Air Permeability Without...", 1994 Nonwovens Conference Proceedings

J. Robert Wagner

An image analyzer was utilized to determine the actual air permeability orifice diameter and the presence of grit and indentations within or near the edge of the orifice which could enable incorrect air permeability to be obtained without being known to the operator. The effect of incorrect orifice diameter apparently is overcome when the air permeability manufacturer calibrates each orifice. When an orifice is lost and a replacement is obtained, the initial calibration chart for that orifice would no long be correct due to diameter differences. Instead, a calibration chart for the replacement orifice should be obtained.

A simple visual scan of the calibration chart revealed one calibration or typographical error when numbers may have been transposed in the calibration chart as supplied by the manufacturer. Statistical curve fitting revealed one additional calibration error in addition to numerous probable air permeability errors when the Merriam Red Oil level is less than two inches.