Textiles - Test methods for nonwovens - Part 15: Determination of air permeability
1 Scope
This part of GB/T 24218 specifies a method for determining the air permeability of nonwovens.
This part is applicable to all kinds of nonwovens, including laminates, which are treated or untreated.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 6529 Textiles - Standard atmospheres for conditioning and testing (GB/T 6529-2008, ISO 139: 2005, MOD)
GB/T 19022-2003 Measurement management systems - Requirements for measurement processes and measuring equipment (ISO 10012: 2003, IDT)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
air permeability
rate of an air flow passing perpendicularly through the specified test area under a prescribed pressure differential within a certain period of time
Note: Air permeability is expressed in litres per square centimetre per second [L/(cm2·s)], or any other equivalent unit.
4 Principle
The flow of air passing perpendicularly through the specified area of the test specimen is measured within a certain period of time, and the air permeability is calculated under a prescribed pressure differential.
5 Apparatus
5.1 Test head, which provides a circular test area of either 20cm2, 38.3cm2 or 50cm2. The tolerance on the test areas shall not exceed 0.5%.
5.2 Clamping system, to secure test specimens, capable of holding the specimen tight enough to the test head without distortion, and ensuring the absence of edge gas leakage beneath the test specimen.
5.3 Vacuum pump, for providing a steady flow of air perpendicularly through the test area of the test specimen and for adjusting the air flow rate that preferably provides pressure differentials of between 100Pa and 2,500Pa (10mmH2O and
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Apparatus
6 Procedure
7 Result calculation
8 Test report
