The present work investigated the permeation behavior at high-pressure of four commercial-grade media used for natural gas filtration. Samples of nonwoven fabrics (cellulose, polypropylene and polyethylene) and of a stainless steel cloth (dutch twilled pattern) were tested under airflow at room temperature, face velocities from 0.01 to 0.21 m/s and absolute pressures from 93 to 693 kPa. Permeability coefficients k(1) and k(2) based on Forchheimer's equation were fitted from experimental data and correlated to other physical properties, such as fiber diameter, medium thickness and packing density. The ranges found for k(1) (5.74-80.96 x 10(-12) m(2)) and k(2) (1.32-19.86 x 10(-7) m) are typical of fiber media used in filtrations applications. The increase of air pressure in the tested range did not induce deformations in the medium structure, but resulted in proportionally higher pressure drop levels due to the increase of gas density. Based on the experimental results with airflow, the pressure drop was simulated for flow of natural gas at 25 degrees C and pressures up to 5000 kPa. Considering the combined influences of thickness and permeability coefficients of each filtering medium, pressure drop was found to decrease in the following order: polypropylene > metallic cloth > cellulose > polyester. (C) 2012 Elsevier Ltd. All rights reserved.