GB/T 12704.1-2009Textiles - Test method for water-vapour transmission of fabrics - Part 1: Desiccant method (English PDF)

Foreword

This document was issued on 19 March 2009 by the State Administration for Market Regulation and the Standardization Administration of the People's Republic of China, and has been in force since 1 January 2010.

It replaces GB/T 12704-1991.

Classification: ICS 59.080.30, CCS W04.

1 Scope

Part 1 of China's national test method for the water-vapour transmission of fabrics, covering the desiccant method. Breathability is the property that decides whether a garment is comfortable, and it is quite separate from air permeability: a waterproof membrane can pass no air at all and still let perspiration through as vapour. The desiccant method measures it in the way the name suggests - a cup of desiccant is sealed under the fabric, placed in a controlled atmosphere and weighed over time, and the mass gained is the vapour that crossed the fabric. It is the upward-cup arrangement, which suits fabrics used with the dry side out and gives the figure quoted for most apparel textiles. The test is slow, sensitive to the conditioning of the atmosphere and to the seal at the rim, and it is the number on which the whole outdoor and sportswear market compares its membranes and coatings.

About this edition

GB/T 12704.1-2009 is the current edition. It was issued on 19 March 2009 and has been in force since 1 January 2010, replacing GB/T 12704-1991.

GB/T 12704-1991 has been superseded: a specification that still cites it is citing a withdrawn edition.

The interval between issue and effect is the transition period. It exists so that producers, laboratories and buyers can requalify products, revise procedures and use up documentation before the new text becomes the one that applies. The date on this page is the official one from the record of the Standardization Administration.

Classification and status

GB/T 12704.1-2009 is classified under ICS 59.080.30, in the field of textile and leather technology. ICS is the International Classification for Standards, the same scheme used by ISO and by the national bodies of most countries, which is what allows a Chinese standard to be placed beside its foreign counterparts on subject rather than on number.

Its Chinese Standard Classification code is CCS W04. CCS is the domestic scheme, a letter for the sector and two digits for the subject within it, and it is the code by which the standard is filed and searched in China.

The GB/T prefix marks a recommended national standard. It is not, in itself, law: it becomes binding when a contract names it, when a regulation or a mandatory standard refers to it, or when a producer declares conformity with it. In practice that covers most of the cases in which it will be read - a purchase specification, an inspection agreement or a certification scheme.

How a Chinese national standard is set out

Chinese national standards are drafted to the rules of GB/T 1.1, which fixes the order in which a standard is set out. The document opens with a foreword recording the issuing bodies, the relationship to any previous edition and the technical committee responsible for it. Clause 1 is the scope. Clause 2 lists the normative references - the other standards that have to be applied together with this one, and without which its requirements cannot be met. Clause 3 gives the terms and definitions. The technical clauses follow: the requirements themselves, the test or measurement methods by which conformity is established, the inspection rules that say how a lot is sampled and judged, and, for a product standard, the provisions on marking, packaging, transport and storage. Annexes, normative or informative, come last.

GB/T 12704.1-2009 runs to 8 pages in the English translation. What is delivered is the complete document in that order: every clause, every table, every figure and every annex of the Chinese original, with the same numbering, so that a reference to a clause number in a contract or a test report points to the same place in both languages.