FEC manufactures an air permeability tester that measures the rate of air flow through fabrics under varying pressures. The tester features exchangeable test areas of 10, 20, 50, and 100 cm2 and measures air flow rates from 9 to 19,400 lph. A digital pressure indicator precisely measures pressure differences up to 999 mm water column. The tester clamps fabric samples between rubber-lined rings and uses a vacuum pump to draw air through the material, with flow measured by rotameters according to ISO and DIN testing standards.