GB/T 2543.2-2001 Textiles — Determination of twist in yarns — Part 2: Untwist-retwist method
1 Scope
This standard specifies a method for the determination of the direction of twist and the amount of twist by the untwist-retwist method.
This method is applicable to the determination of twist in single spun yarns. It is designed primarily for yarns in packages, but by the application of special precautions the procedures can be used for yarns taken from fabrics.
This standard is not applicable to open-end spun yarns, false-twist yarns, self-twist yarns and air-jet yarns.
This method is not applicable to yarns that stretch more than 0.5% when the tension increases from 0.5 cN/tex to 1.0 cN/tex. Exceptions apply if approved by the agreement. Such yarns may be tested under special conditions of tension which are accepted by all parties interested in the test results.
This method is not applicable to yarns that are too large to permit their being placed in the clamps of testing apparatus without crushing or distortion severe enough to affect the test results.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, all editions cited are valid. All normative references are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the latest editions of the normative standards indicated below.
GB 6529-1986 Textiles - Standard atmospheres for conditioning and testing
3 Definitions
For the purposes of this standard, the following definitions apply.
3.1
twist
number of turns about the axis of a yarn based on its nominal gauge length before untwisting Twist should preferably be expressed as turns per metre (turns/m), or as turns per centimeter (twist/cm).
Contents
Foreword II
1 Scope
2 Normative references
3 Definitions
4 Principle
5 Apparatus
6 Standard atmosphere
7 Sampling
8 Test specimens
9 Determination of direction of twist
10 Determination of amount of twist
11 Calculations
12 Test report
Annex A (Informative) Suggested procedure for sampling
GB/T 2543.2-2001 Textiles — Determination of twist in yarns — Part 2: Untwist-retwist method
1 Scope
This standard specifies a method for the determination of the direction of twist and the amount of twist by the untwist-retwist method.
This method is applicable to the determination of twist in single spun yarns. It is designed primarily for yarns in packages, but by the application of special precautions the procedures can be used for yarns taken from fabrics.
This standard is not applicable to open-end spun yarns, false-twist yarns, self-twist yarns and air-jet yarns.
This method is not applicable to yarns that stretch more than 0.5% when the tension increases from 0.5 cN/tex to 1.0 cN/tex. Exceptions apply if approved by the agreement. Such yarns may be tested under special conditions of tension which are accepted by all parties interested in the test results.
This method is not applicable to yarns that are too large to permit their being placed in the clamps of testing apparatus without crushing or distortion severe enough to affect the test results.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, all editions cited are valid. All normative references are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the latest editions of the normative standards indicated below.
GB 6529-1986 Textiles - Standard atmospheres for conditioning and testing
3 Definitions
For the purposes of this standard, the following definitions apply.
3.1
twist
number of turns about the axis of a yarn based on its nominal gauge length before untwisting Twist should preferably be expressed as turns per metre (turns/m), or as turns per centimeter (twist/cm).
Contents of GB/T 2543.2-2001
Contents
Foreword II
1 Scope
2 Normative references
3 Definitions
4 Principle
5 Apparatus
6 Standard atmosphere
7 Sampling
8 Test specimens
9 Determination of direction of twist
10 Determination of amount of twist
11 Calculations
12 Test report
Annex A (Informative) Suggested procedure for sampling
