Model C-522 is designed to measure the permeability of materials based on ASTM standards. It measures pressure difference and flow rate in the ranges recommended by ASTM. Resistance characteristics are computed from measured values. A number of characteristics of the acoustical material, including specific airflow resistance (rayl), airflow resistivity (rayl/m) and airflow resistance (ohm) are reported. When performing a test, the sample is placed in the sample chamber and sealed using a top and a bottom o-ring to prevent air leakage through the sides of the sample. The sample diameter, thickness and desired test settings (like pressure drop, flowrate) are entered into the computer. Once the test is complete the report software is used for data reduction and calculation of permeability values. A range of models can measure the permeability of a sample in Rayls, Gurley, Frazier and Darcy, as well as other units.
Porous Materials Inc. (PMI)