Determination of woven fabric impact permeability index

Abstract

An uncertainty in measuring a feature of technical fabrics called ‘impact permeability’ has been assessed in the form of impact permeability index. Impact permeability describes the difference in the behaviour of a fabric in dynamic airflow conditions in relation to its behaviour in static conditions. A mathematical model of pressure drop in woven fabric, which is formed as a result of impact airflow through the product, has been presented. For the assessment of inaccuracy in impact permeability index determination, the procedures described in ‘guide to the expression of uncertainty in measurement’ are used. An example of calculating uncertainty budgets of the parameters analysed has also been reported. It is observed that the method of determination of impact permeability index is useful. The index is a good measure of impact permeability for the technical fabrics with respect to their flow properties