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GB/T 35872-2018Cotton - Cotton of sterile seeds (English PDF)

棉花不孕籽棉

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Issued by

AQSIQ; SAC

Level / Type

National · Recommended

Issue date

February 6, 2018

Implementation date

September 1, 2018

Scope

GB/T 35872-2018 is the English-translated version of 棉花不孕籽棉.

China's national standard for cotton of sterile seeds, the fibre recovered from the unfertilised seed that the gin stand and the lint cleaner throw out with the waste. A sterile seed is a cotton seed that was never fertilised: it stays white, small and flat, and although it carries fibre it is separated out of the lint stream because it will not gin cleanly. Ginneries that process large tonnages accumulate that material in quantity, and rather than burn it they reclaim the fibre from it and sell it as a lower grade cotton for coarse yarns, wadding and nonwovens. What was missing was any agreed way to describe it, so a by-product with real value was bought and sold by eye and by argument, with no common language for colour, length or the amount of very short fibre it contains. This standard supplies that language: it specifies the technical requirements, the test methods and the marking, packaging, storage and transport of cotton of sterile seeds, and applies to inspection at the processing, the trading and the using stage. Its centre is a quality mark, of the form RC2251, that packs the type, the colour grade, the length grade and the short fibre content band into one code a buyer can read off the bale. Short fibre content is the variable that matters most here, because material reclaimed from gin waste is by nature full of it, and the standard is the only place that fixes a normative test method for measuring it in this product.

Document preview — GB/T 35872-2018

National Standard of the People's Republic of China

ICS: 59.060.10
Classification: B 32

Issued by: General Administration of Quality Supervision, Inspection and Quarantine; Standardization Administration of the PRC

1 Scope
2 Normative references
3 Terms and definitions
4 Technical requirements
4.1 Quality assessment indexes of cotton of sterile seeds
4.2 Method of expressing the quality mark of cotton of sterile seeds
4.3 Technical requirements for the colour grade and the short fibre content of cotton of sterile seeds
4.4 Length
4.5 Moisture regain
4.6 Trash content
5 Test methods
5.1 Preparation of the sample
5.2 Quality inspection
5.3 Inspection of the conditioned weight
5.4 Inspection of the conditioned weight of a lot of bales
5.5 Rounding of numerical values
6 Marking, packaging, storage and transport
Annex A (normative) Test method for the short fibre content of cotton of sterile seeds

Foreword

GB/T 35872-2018 was issued on 6 February 2018 by the General Administration of Quality Supervision, Inspection and Quarantine and the Standardization Administration of the People's Republic of China, and has been in force since 1 September 2018. The /T in the designation marks it as a recommended national standard.

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This standard was proposed by, and is under the jurisdiction of, the China Fiber Inspection Bureau. The drafting unit is the Hubei Provincial Fiber Inspection Bureau.

1 Scope

This standard specifies the technical requirements, the test methods and the marking, packaging, storage and transport of cotton of sterile seeds.

This standard applies to the inspection of cotton of sterile seeds at the processing, trading and use stages.

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including all amendments) applies.

GB/T 6097 Test methods for cotton fibres - Sampling

GB/T 6102.1 Test method for moisture regain of raw cotton - Oven-drying method

GB/T 6102.2 Test method for moisture regain of raw cotton - Electrical resistance method

GB/T 6499 Test method for trash content of raw cotton

GB/T 8170 Rules of rounding off for numerical values and expression and judgement of limiting values

GB/T 13786 Simulated daylight illumination for the cotton classing room

GB/T 19617 Test method for cotton length - Hand-stapling and ruler measuring method

3 Terms and definitions

The following terms and definitions apply to this document.

3.1 sterile seeds: Cotton seeds that have not been fertilised, white in colour and flat and round in shape.

3.2 cotton of sterile seeds: The cotton fibre obtained by processing the sterile seeds still carrying fibre and other such matter that are discharged from the gin stand and from the lint cleaner.

3.3 staple fibre: Cotton fibre whose length is 16 mm or less.

3.4 foreign fibre: Non-cotton fibre and non-natural-coloured cotton fibre mixed into the cotton of sterile seeds, such as chemical fibre, hair, silk, hemp, plastic film, plastic rope and dyed thread, rope or cloth.

3.5 gross weight: The sum of the weight of the cotton of sterile seeds and of its packaging.

3.6 net weight: The weight remaining after the weight of the packaging has been deducted from the gross weight.

3.7 conditioned weight: The weight obtained by converting the net weight, on the basis of the actual trash content and the actual moisture regain, to the standard trash content and the conditioned moisture regain.

4.1 Quality assessment indexes of cotton of sterile seeds

The quality assessment indexes of cotton of sterile seeds comprise the colour grade, the length, the short fibre content, the foreign fibre, the moisture regain and the trash content.

4.2 Method of expressing the quality mark of cotton of sterile seeds

The quality mark of cotton of sterile seeds is expressed by the principal colour grade, the length grade and the short fibre content band, in that order: type code, colour grade code, length grade code, short fibre content band.

The type code for cotton of sterile seeds is 'RC'. The colour grade codes are '1' for grade one and '2' for grade two. The length grade code is '24' to '27' for lengths from 24 mm to 27 mm. The short fibre content bands one and two are shown by the ordinal figures '1' and '2'.

Example: RC2251 means grade two cotton of sterile seeds, length 25 mm, short fibre content band 1.

4.3 Technical requirements for the colour grade and the short fibre content of cotton of sterile seeds

The technical requirements for the colour grade and the short fibre content of cotton of sterile seeds are given in Table 1.

Grade one is described as white in colour, slightly light grey, not bright; or milky white with a light yellow cast, somewhat bright. Within grade one, short fibre content band 1 is a short fibre percentage of not more than 30 per cent and band 2 is more than 30 per cent.

Grade two is described as grey-white or grey and dull; grey-white with a dull yellow cast, with light yellow spots; dull yellow with visible grey spots; or yellow in colour and not bright. Within grade two, short fibre content band 1 is a short fibre percentage of not more than 35 per cent and band 2 is more than 35 per cent.

4.4 Length

The length is graded in steps of 1 mm, as follows: 24 mm, comprising 24.9 mm and below; 25 mm, comprising 25.0 mm to 25.9 mm; 26 mm, comprising 26.0 mm to 26.9 mm; 27 mm, comprising 27.0 mm and above.

4.5 Moisture regain

The conditioned moisture regain of cotton of sterile seeds is 8.5 per cent.

4.6 Trash content

The standard trash content of cotton of sterile seeds is 5.0 per cent.

5.1 Preparation of the sample

5.1.1 Sampling of baled cotton of sterile seeds is carried out by drawing one bale out of every ten; a quantity of fewer than ten bales counts as ten bales.

5.1.2 After the top of the bale has been opened, the surface layer of cotton of sterile seeds is discarded and sample A is drawn, each sample having a total mass of not less than 300 g, to form the inspection lot sample. Sample B is drawn at a depth of 10 cm to 15 cm from the surface of the bale, each sample being about 100 g. Sample A is used for the inspection of the colour grade, the length and the foreign fibre; 50 g drawn at random from several points of the A lot sample forms one laboratory sample for the inspection of the short fibre content, and 600 g drawn at random from several points of the A lot sample forms one laboratory sample for the inspection of the trash content. Sample B is used for the inspection of the moisture regain; it forms the moisture regain inspection lot sample and, once drawn, shall be placed at once in a closed container and inspected within 24 h.

5.2 Quality inspection

5.2.1 Inspection of the colour grade. 5.2.1.1 The colour grade is inspected by the sensory method, the colour grade being determined by comparison with the written description of the colour characteristics. 5.2.1.2 The inspection of the colour grade shall be carried out in a cotton classing room; the classing room shall comply with GB/T 13786 or shall have north-facing daylight. 5.2.1.3 The colour grade of each sample of the A lot sample is inspected one by one and the results recorded. 5.2.1.4 The percentage accounted for by each grade in the lot sample is calculated, and the colour grade with the largest percentage is taken as the principal colour grade of that lot of cotton of sterile seeds, rounded to one decimal place.

5.2.2 Inspection of the length. 5.2.2.1 The length is inspected by the hand-stapling and ruler measuring method in accordance with GB/T 19617. 5.2.2.2 The arithmetic mean of the lengths of the individual specimens in the A lot sample and the percentage of each length grade are calculated; the length grade corresponding to the mean length is taken as the length grade of that lot of cotton of sterile seeds. 5.2.2.3 The result of the length inspection is kept to one decimal place.

5.2.3 Inspection of foreign fibre. Each sample of the A lot sample is inspected for foreign fibre one by one, by manual picking, as a qualitative inspection; the result is 'present' or 'absent'.

5.2.4 Inspection of the short fibre content. 5.2.4.1 The short fibre content is inspected by the hand-stapling method or by the Rolla method, the Rolla method being the reference. 5.2.4.2 For a lot of 100 bales or fewer, two test specimens are taken for inspection and the mean of the two results is taken as the short fibre content of that lot; for a lot of more than 100 bales, three test specimens are taken and the mean of the three results is taken as the short fibre content of that lot. 5.2.4.3 The test method for the short fibre content of cotton of sterile seeds is carried out in accordance with Annex A.

5.3 Inspection of the conditioned weight

5.3.1 Inspection of the trash content. The method for inspecting the trash content of baled cotton of sterile seeds is carried out in accordance with GB/T 6499.

5.3.2 Inspection of the moisture regain. 5.3.2.1 The moisture regain is inspected by the electrical resistance method or the oven-drying method, the oven-drying method being the reference. 5.3.2.2 The method for inspecting the moisture regain is carried out in accordance with GB/T 6102.1 or GB/T 6102.2.

5.4 Inspection of the conditioned weight of a lot of bales

5.4.1 The inspection of the conditioned weight takes the lot as its unit and every bale is weighed. The accuracy of the weighing instrument shall not be lower than 1 part per thousand, and the weight should be as close as possible to the maximum capacity of the instrument.

5.4.2 Depending on the size of the lot, 2 to 5 representative bales of cotton of sterile seeds are drawn from the lot sample, opened and the packaging weighed, and the mean weight of the packaging of a single bale is calculated, rounded to 0.01 kg.

5.4.3 The net weight of each lot of cotton of sterile seeds is calculated by formula (1), rounded to 0.001 t: W2 = (W1 - N x M) / 1 000, where W2 is the net weight of the inspection lot of cotton of sterile seeds in tonnes (t), W1 is the total gross weight of the inspection lot in kilograms (kg), N is the total number of bales in the inspection lot and M is the mean packaging weight per bale in kilograms (kg).

5.4.4 The conditioned weight of each lot of cotton of sterile seeds is calculated by formula (2), rounded to 0.001 t: W = W2 x (100 - Zmean) x (100 + R0) / [(100 - Z0) x (100 + Rmean)], where W is the conditioned weight of the inspection lot in tonnes (t), Zmean is the mean trash content of the inspection lot in per cent, R0 is the conditioned moisture regain of cotton of sterile seeds in per cent, Rmean is the mean moisture regain of the inspection lot in per cent and Z0 is the standard trash content of cotton of sterile seeds in per cent.

5.5 Rounding of numerical values

Carried out in accordance with GB/T 8170.

6 Marking, packaging, storage and transport

6.1 Each bale of cotton of sterile seeds shall be marked in black paint at both ends of the bale with the place of origin (province, city and county), the processing unit, the quality mark, the lot number, the bale number, the gross weight and the date of production.

6.2 When cotton of sterile seeds is baled the packaging shall be complete and intact, and oily cotton, floor sweepings and harmful foreign matter shall not be mixed into the bale.

6.3 When baled cotton of sterile seeds is stored it shall be stacked separately according to the place of origin, the lot and the colour grade, and attention shall be paid to ventilation, to protection from damp and to the prevention of mould and of fire.

6.4 During transport, cotton of sterile seeds shall be protected against fire, immersion in water, rain and contamination.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 10 pages — is available in the English PDF.

Referenced standards

Normative references

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