6.1 This test method has been developed as a result of research performed by Air Dispersion Limited (Manchester, UK) and funded by the Barrier Test Consortium Limited. The results of this research have been published in a peer-reviewed journal.4 This research demonstrated that testing the barrier performance of porous packaging materials using microorganisms correlates with measuring the filtration efficiency of the materials.

6.2 This test method does not require the use of microbiological method; in addition, the test method can be conducted in a rapid and timely manner.

6.3 When measuring the filtration efficiency of porous packaging materials a typical filtration efficiency curve is determined (see Fig. 1). Since the arc of these curves is dependent upon the characteristics of each individual material, the appropriate way to make comparison among materials is using the parameter that measures maximum penetration through the material.

FIG. 1 A Typical Curve Showing Penetration as a Function of Flow Rate

Note 1: The point of maximum penetration is indicated by the upward pointing triangle.

6.4 The particle filtration method is a quantitative procedure for determining the microbial barrier properties of materials using a challenge of 1.0 µm particles over range of pressure differentials from near zero to approximately 30 cm water column (WC) (2942 Pa). This test method is based upon the research of Tallentire and Sinclair4 and uses physical test methodology to allow for a rapid determination of microbial barrier performance.