GB/T 6499-2022Test method for percentage of trash content in raw cotton (English PDF)

3.1 Trash

Non-cotton fiber materials contained in raw cotton and fibers attached to these materials, such as sand, branches and leaves, boll shells, insect feces, insect corpses, cottonseeds, seed cotton, seed coat fragments, motes, seed-coat fragments with lint, soft seed epidermis, etc.

3.2 Percentage of trash

The percentage of the mass of trash in the raw cotton sample to the mass of the sample.

5.1 Method A - raw cotton trash analyzer method

5.1.5.5 All test results shall be rounded off according to GB/T 8170.

5.1.1 Principle

5.1.2 Instruments and tools

5.1.2.1 Raw cotton trash analyzer, which consists of a cotton feeding table, a cotton feeding roller, a licker-in roller, a dust removal knife, a streamline plate, a cotton stripping knife, a dust cage, a trash box, a fan, and a motor.

5.1.2.2 Balance: range >= 100 g, division value 0.01 g

5.1.2.3 Brown brush, tweezers […]

5.1.3 Sample preparation

From the laboratory sample, use the quartering method to extract two (50 ± 1) g test samples and one (50 ± 1) g spare sample, and weigh the sample mass with a balance to an accuracy of 0.1 g.

5.1.4 Test steps

5.1.4.1 Start the machine and run for 1 min ~ 2 min, then stop the machine to clean the trash box, clean cotton box, cotton feeding table, and licker-in roller.

5.2.1 Principle

According to the principle of aerodynamics, the sample is fed into the fully automatic raw cotton trash analysis system; under the action of the combing roller, the sample is loosened; under the action of the dust removal knife and streamline knife, the fibers and trashes in the sample are separated; the fibers in the sample are attached to the surface of the dust cage with the movement of the airflow and fall into the waste cotton box; the trashes in the sample fall on the electronic scale tray in the trash box because of their greater specific gravity than the fibers, and the trashes are automatically weighed; through the automatic calculation system, the percentage of trash content in raw cotton is obtained.

According to the principle of aerodynamics, the cotton fibers and trashes attached to them are separated by the combined action of high-speed rotating mechanical parts and airflow, the trashes are collected and weighed, and the percentage of trash mass to the sample mass is calculated to obtain the percentage of trash content in raw cotton.

5.2.2 Instruments and reference materials

5.2.2.1 Fully automatic raw cotton trash analysis system, which consists of an efficient trash separation and collection system, an automatic trash weighing and calculation system, etc.

5.2.2.3 Reference material of percentage of trash content in raw cotton, GSB 11-3812.

5.2.2.2 Balance: range >= 100 g, division value 0.01 g

5.2.3 Sample preparation

From the laboratory sample, use the quartering method to extract two (100 ± 10) g test samples and one (100 ± 10) g spare sample, and weigh the sample mass with a balance to an accuracy of 0.1 g.

5.2.4 Equipment calibration and calibration check

Select the reference material of percentage of trash content in raw cotton (GSB 11-3812), and calibrate according to the calibration procedure of the fully automatic raw cotton trash analysis system. If the test difference of the reference material is within the uncertainty range of the reference material, it is determined to have passed the calibration.

For the fully automatic raw cotton trash analysis system in use, reference materials shall be selected regularly for calibration checks. If the test difference is within the uncertainty range of the reference material, it is determined to have passed the calibration check.

5.2.5 Test steps

5.2.5.1 Check and empty the waste cotton box and trash box of the instrument.

5.2.5.2 Select the instrument test procedure.

5.2.5.3 Enter the cotton sample type (saw ginned cotton or roller ginned cotton) and sample information.

5.2.5.4 Spread the test sample evenly on the sample table or automatic cotton feeding device.

5.2.5.5 The test instrument automatically performs steps such as combing, trash collection, trash weighing, and result calculation on the cotton sample.

5.2.5.6 Repeat test steps 5.2.5.1 ~ 5.2.5.5 to test the second sample.

5.2.6 Calculation of test results and rounding off of numerical values

5.2.6.1 The percentage of trash content of a single sample shall be rounded off to two decimal places according to GB/T 8170; the final percentage of trash content of sample shall be expressed as the average value of the samples and rounded off to one decimal place.

5.2.6.2 For saw ginned cotton with percentage of trash content less than 2.5 %, if the difference between the two test results is greater than 0.34, test a spare sample; the final result shall be expressed as the arithmetic mean of the three samples and rounded off to one decimal place.

5.2.6.3 For saw ginned cotton with percentage of trash content greater than 2.5 %, if the difference between the two test results is greater than 0.57, test a spare sample; the final result is expressed as the arithmetic mean of the three samples and rounded off to one decimal place.

5.2.6.4 For roller ginned cotton, if the difference between the two test results is greater than 0.95, test a spare sample; the final result is expressed as the arithmetic mean of the three samples and rounded off to one decimal place.

5.2.6.5 All test results shall be rounded off according to GB/T 8170.