ISO/PRF 2403

Textiles -- Cotton fibres -- Determination of micronaire value

Textiles -- Fibres de coton -- Détermination de l'indice micronaire

General Information

• Status: Published
• ICS: 59.060.10 - Natural fibres
• Technical Committee: ISO/TC 38/SC 23 - Fibres and yarns
• Drafting Committee: ISO/TC 38/SC 23/WG 2 - Fibres - Natural cellulosic

RELATIONS

• Revised: ISO 2403:2014 - Textiles -- Cotton fibres -- Determination of micronaire value
• Effective Date: 23-Apr-2020

Standards Content (sample)

INTERNATIONAL ISO
STANDARD 2403
Third edition
Textiles — Cotton fibres —
Determination of micronaire value
Textiles — Fibres de coton — Détermination de l'indice micronaire
PROOF/ÉPREUVE
Reference number
ISO 2403:2021(E)
ISO 2021
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ISO 2403:2021(E)
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ISO 2403:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1  Scope ................................................................................................................................................................................................................................. 1

2  Normative references ...................................................................................................................................................................................... 1

3  Terms and definitions ..................................................................................................................................................................................... 1

4  Principle ........................................................................................................................................................................................................................ 1

5  Apparatus and materials.............................................................................................................................................................................. 1

6  Conditioning .............................................................................................................................................................................................................. 2

7  Preparation of test specimen .................................................................................................................................................................. 2

8  Procedure..................................................................................................................................................................................................................... 2

9  Calculation and expression of results ............................................................................................................................................. 3

10  Test report ................................................................................................................................................................................................................... 3

Annex A (informative) Method of calibration of instruments .................................................................................................... 5

Annex B (informative) Precision experiment.............................................................................................................................................. 6

Annex C (informative) Comparison experiment ....................................................................................................................................... 7

Bibliography ................................................................................................................................................................................................................................ 9

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ISO 2403:2021(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 38, Textiles, Subcommittee SC 23, Fibres

and yarns.

This third edition cancels and replaces the second edition (ISO 2403:2014), which has been technically

revised.
The main changes compared to the previous edition are as follows:
— an introduction clause has been added;

— a short description of the available apparatus, operation details and reference to calibration method

in 5.2, Notes 1 and 2, respectively, has been added ;

— permission of the use of two different sample preparation methods have been added in 7.2;

— the specification of applied sample preparation method, the date of the test, any deviations from the

procedure, and any unusual features observed have been added in the test report in Clause 10;

— former Annexes B and C (operation of different instruments) have been removed;

— a new informative Annex B with precision data for micronaire measurements has been added;

— a new informative Annex C with precision data for comparison of the both test specimen preparation

methods has been added;
— a bibliography has been added;
— grammar and linguistic consistency have been reviewed.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
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ISO 2403:2021(E)
Introduction

The micronaire value, one of the most important cotton fibre quality parameters, is measured on a

plug of cotton fibres, it hence represents an average value. Due to a simple test specimen preparation, a

measurement is carried out in relatively short time and thereby leads to fast testing results.

Based on the air permeability of a compressed cotton fibre test specimen, early manual micronaire

testers used a mechanical air-flow meter, where a float sensor indicates the amount of air flowing

through the test specimen, and a mechanical manometer showing the air pressure difference across the

test specimen. Modern micronaire testers generally use electronic sensors for both, the air flow and the

pressure difference.

In any case, the dimensionless micronaire value is calculated from the air flow through the test

specimen and the pressure difference along the test specimen. Micronaire values are within a scale of 2

and 8, where a value of 2 represents a low air permeability (high packing density of the test specimen,

caused by very fine and/or immature fibres) and a value of 8 represents a high air permeability (low

packing density of the test specimen, caused by very coarse and/or mature fibres).

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INTERNATIONAL STANDARD ISO 2403:2021(E)
Textiles — Cotton fibres — Determination of micronaire
value
1  Scope

This document specifies a method of determining the micronaire value of loose disorientated cotton

fibres taken from bales, laps and slivers, or other sources of lint cotton.
2  Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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.

ISO 139, Textiles — Standard atmospheres for conditioning and testing
ISO 1130, Textile fibres — Some methods of sampling for testing
3  Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
micronaire value
measure for the air permeability of a mass of cotton under specified conditions

Note 1 to entry: The micronaire scale is based on a range of cottons to which micronaire values have been

assigned by international agreement.

Note 2 to entry: It is expressed in terms of an arbitrary scale, the so-called micronaire scale.

4  Principle

Air is passed through a test specimen consisting of a plug of fibres. The permeability is indicated on a

scale for recording variations in either the rate of flow through, or the pressure difference across, the

plug. The mass and volume of the test specimen are either a constant for a given type of instrument or

varied appropriately in relation to each other. The scale indicating variations in permeability can be

calibrated in arbitrary units of micronaire value or marked in the appropriate absolute units of rate of

flow or of pressure difference and a table or graph provided for conversion of the observed readings

into micronaire values.
5  Apparatus and materials

5.1  Balance, of sufficient capacity to weigh the test specimen required for the airflow instrument used,

with an accuracy of ±0,2 %.
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ISO 2403:2021(E)
5.2  Airflow instrument, whose principal parts are as follows.

5.2.1  Compression cylinder with perforated ends of such dimensions that with the prescribed

mass of test specimen each cubic centimetre shall contain between 0,16 g and 0,30 g of cotton when

compressed.

5.2.2 Means for measuring the air permeability of the test specimen, comprising, for example:

a) a suitable air pump;

b) one or more valves or other means for controlling the flow of air through, or the pressure difference

across, the test specimen in the compression cylinder;

c) a manometer for measuring the required air pressure difference across the test specimen and a

flowmeter for indicating the rate of airflow through it.

NOTE 1 There are several models of airflow instruments, which vary only in details of construction and

operation. Any details of the operation are described in the manufacturer's instructions included with the

instrument.

NOTE 2 For information on the method of calibration of airflow instruments, see Annex A.

5.3  International calibration cotton standards (see A.1).
6  Conditioning

6.1 Condition samples in the standard atmosphere for 4 h in moving air (or alternatively for 12 h in

still air) or for a shorter time if the change in mass in a 2 h period does not exceed 0,25 % before weighing

and testing the test specimen. Preconditioning is not required.

6.2 Weigh and test the test specimen in the standard atmosphere for conditioning in accordance with

ISO 139.
7  Preparation of test specimen
7.1 Take test specimens in accordance with
...