Air Permeability Test Methods and Acceptable Limits
Air Permeability is verified through ISO 9237 air permeability. Knowing how the method works avoids rejecting fabric that actually meets the requirement.
Method overview
ISO 9237 air permeability defines sample size, conditioning and calculation, so values are comparable only within the same revision. Working figures for Air Permeability normally sit around 50-500 mm/s depending on structure in mainstream production. Note ISO 9237 air permeability on the tech pack so nobody tests against an older revision.
Result interpretation
Read the value together with construction notes; 50-500 mm/s depending on structure is only meaningful for similar fabrics. Record elastane content alongside Air Permeability, because blends shift the measured value. A result outside 50-500 mm/s depending on structure usually points to process drift rather than to the fibre itself.
Typical limits
Buyers commonly write 50-500 mm/s depending on structure with a stated tolerance, then verify against ISO 9237 air permeability. Keeping reference values for Air Permeability lets suppliers quote without extra sampling rounds. Ask for conditioning details together with ISO 9237 air permeability, since both affect the reading.
Sources of variation
Conditioning time, operator technique and shade all influence the result. Working figures for Air Permeability normally sit around 50-500 mm/s depending on structure in mainstream production. Note ISO 9237 air permeability on the tech pack so nobody tests against an older revision.
Documentation
Record the standard revision on every report, because older versions can differ from current practice. Record elastane content alongside Air Permeability, because blends shift the measured value. A result outside 50-500 mm/s depending on structure usually points to process drift rather than to the fibre itself.
