ISO 9237 pdf download.Textiles一Determination of the permeability of fabrics to air
1 Scope
This International Standard describes a method for measuring the permeability of fabrics to air and is ap- plicable to most types of fabrics, including industrial fabrics for technical purposes, nonwovens and made-up textile articles that are permeable to air.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publi- cation, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most re- cent editions of the standards indicated below. Members of IEC and ISO maintain registers of cur- rently valid International Standards. ISO 48:1994, Rubber, vulcanized or thermoplastic – Determination of hardness (hardness between 10 IRHD and 100 IRHD). ISO 139:1973, Textiles – – Standard atmospheres for conditioning and testing. ISO 10012-1:1992， Quality assurance requirements for measuring equipment – Part 1: Metrological confirmation system for measuring equipment.
3 Definition
For the purposes of this International Standard, the following definition applies. 3.1 air permeability: Velocity of an air flow passing perpendicularly through a test specimen under speci- fied conditions of test area, pressure drop and time.
4 Principle
The rate of flow of air passing perpendicularly through a given area of fabric is measured at a given pressure difference across the fabric test area over a given time period.
5 Sampling
Select samples either in accordance with the pro- cedure laid down in the material specification for the fabric, or as agreed between the interested parties. In the absence of specification, follow the example of sampling given in annex B.
6 Atmospheres for conditioning and testing
The atmospheres for preconditioning， conditioning and testing shall be as specified in ISO 139.
7 Apparatus
Metrological confirmation of the test apparatus shall be carried out in accordance with ISO 10012-1. 7.1 Circular specimen holder, with an orifice al- lowing the test to be carried out on an area of 5 cm*, 20 cm’. 50 cm2 or 100 cm2. The tolerance on the test area shall not exceed 士0,5 %. NOTE 1 Adequate support of the test specimen, particu- larly for large test surfaces, is recommended. 7.2 Means for clamping, to secure the specimen without distortion. NOTE 2Care should be taken to prevent leakage of air around the edges of the test specimen. Alternatively the leakage may be measured separately and subtracted from the test results. 7.3 Guard ring device, to prevent leakage, for Op- tional use in conjunction with the clamping means (7.2), (see A.2.1). 7.4 Pressure gauge or manometer, connected to the test head to indicate a pressure drop across the specimen test area of 50 Pa，100 Pa，200 Pa or 500 Pa, with an accuracy of at least 2 %. 7.5 Means for drawing a steady flow of air al controlled temperature and humidity through the specimen holder and for adjusting the flowrate to produce a pressure drop across the specimen of be- tween 50 Pa and 500 Pa. 7.6 Flowmeter, volumetric counter or measuring aperture, indicating the rate of air flow in cubic decimetres per minute (litres per minute) with an ac- curacy of at least士2 %. NOTE 3 Flowmeters or volumetric counters measuring the rate of air flow in cubic centimetres per second (or other suitable units) may be used if the required accuracy of at least土2 % is maintained.
Mount the test specimen in the circular specimen holder (7.1) with sufficient tension to eliminate wrin- kles, if any, taking care that the fabric is not distorted in its own plane. Avoid selvedges and areas with creases or folded places. For fabrics for which the air permeability may be different between the two faces of the fabric, specify in the test report [see 11 a)2)] which face was tested. Clamp specimens coated on one side with the coating towards the lower pressure side to prevent air leakage. Start the suction fan or other means (7 .5) to force the air through the test specimen and adjust the flow of air gradually till a pressure drop, as recommended above, is achieved across the test area of the fabric. Record the air flow (see 7.6) after at least 1 min or until steady conditions are achieved.