GB/T 18146.2-2015Hemp fiber—Part 2: Raw white hemp sliver (English PDF)

1 Scope

This Part of GB/T 18146 specifies technical requirements, sampling quantity and sampling method, test method, quality assessment, inspection rules, packaging, marking, transportation and storage for raw white hemp sliver.

This Part is applicable to quality assessment of raw white hemp sliver.

2 Normative references

The following referenced documents are indispensable for the application 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.

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

GB/T 9995, Determination of moisture content and moisture regain of textile - Oven-drying method

GB/T 18147.1, Test method for hemp fibre - Part 1: Test method for oil content of hemp fibre

GB/T 18147.3, Test method for hemp fiber - Part 3: Test method for length of hemp fiber

GB/T 18147.4, Test method for hemp fiber - Part 4: Test method for fineness of hemp fiber

GB/T 18147.5, Test method for hemp fiber - Part 5: Test method for breaking strength of hemp fiber

GB/T 18147.6, Test method for hemp fiber - Part 6: Test method for defect in hemp fiber

3 Technical requirements

3.1 The raw white hemp sliver is divided into first, second and third categories according to the fineness. Each category is divided into first class and second class. The products lower than the second class are substandard.

4 Sampling quantity and sampling method

4.2.1.1 Sampling for moisture regain test: Randomly draw a hemp ball from each piece.

Each hemp ball is sampled about 50g (half shall be taken from the core and the outer layer of the hemp ball). Immediately pack into an airtight container for moisture regain testing.

4.2.1.2 Sampling for appearance quality inspection: Take 2 hemp silvers from each hemp ball in each piece. Each silver is 3m. There are 10 silvers in total, for appearance quality inspection.

4.2.1.3 Sampling for quality coefficient of variation inspection per meter: From the samples after appearance quality inspection, extract 2 from each piece. Each one is 1m.

There are 20 in total. Measure the coefficient of variation of the mass per meter.

4.2.1.4 In the specimens for which the coefficient of variation of mass per meter has been measured, randomly extract 3 hemp slivers to form a laboratory sample for test sampling:

a) Sampling for oil content test: Take 1 specimen from each hemp sliver. Each is about 5g. Measure the oil content.

b) Sampling for length test: Take 1 specimen from each hemp sliver. Each is about 500mg. Measure the fiber length.

c) Sampling for fineness test: Take 1 specimen from each hemp sliver. Each is about 300mg. Measure the fineness.

d) Sampling for breaking strength test: Take 4 specimens from each hemp sliver. Each is about 8mg. Measure the breaking strength.

e) Sampling for hemp grain and hard strip rate test: Take 1 specimen from each hemp sliver. Each is about 1g. Measure the hemp grain and hard strip rate.

5 Test methods

5.3.2.4

Calculate the coefficient of variation of mass per meter according to formula (3). The result is rounded to one decimal place.

Where, CV - The coefficient of variation of mass per meter; S - Standard deviation of mass per meter, in grams (g); m - The average mass of the specimen per meter, in grams (g).

5.3.2.5

The numerical rounding of the calculation results is carried out according to GB/T 8170.