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GB/T 450 paper and paperboard samples are taken in g. GB/T 450 sampling. g. Weigh the container containing the sample and calculate the mass of the sample. Mm, sample strips with a length of not less than 150 mm. The total mass is at least 50 g, immediately loaded into the container, the container containing the sample is weighed, and the mass of the sample is calculated. Mm strip, and cut paper or cardboard within 150mm from the edge of the original sample. After cutting, remove the top and bottom strips, combine the two groups into one sample, and cut the two samples from the side. Make two other samples, each with two samples, each sample having a mass of at least 50g. Immediately put each sample into the container, weigh each container containing the sample strip, and calculate The mass of each sample.
This standard is equivalent to the use of international standards
1 Subject content and scope of application
This standard specifies methods for determining moisture in paper and board during sampling.
This standard applies to the determination of moisture in various paper and board.
This standard does not apply to the determination of moisture in paper and board containing any substance that can be volatilized other than water at the specified test temperature.
2 Reference standard
3 definition
Moisture refers to the ratio of the reduced mass to the original mass of the sample when the paper or paperboard is baked to constant weight at the specified drying temperature, expressed as a percentage.
4 instruments
4.1 Balance: Sense 0.001
4.2 Sample container: For sample and weighing, it requires good sealing.
4.3 Dryer.
4.4 Oven: The temperature can be controlled at 105+2.
5 Container preparation
Prior to sampling, the clean, dry containers are numbered and equilibrated in the atmosphere, then each container is weighed and capped.
6 sampling
Should follow
7 Sample selection, preparation and weighing
7.1 When the unit is an order or a package
7.1.1 Determination of the average moisture content of a batch
The paper or paperboard has a basis weight less than or equal to 225.
Take at least 4 consecutive samples from the center of each order or package, and quickly fold or cut the sample into the container. The quality of the sample contained in the container is at least 50.
Paper or cardboard has a basis weight greater than 225.
Take one or more samples from the middle of each pack or each order. Take a width of 50-75
7.1.2 Water change between the middle and the side of the flat sample
Take several samples in succession from the middle of each order or each package, and cut these samples into 50-75 as shown below.
7.2 When the unit is the sample layer of mm in the reel, then the sample layer is laid flat, cut the sample strips with a width of 50-75mm in the longitudinal direction, and cut a set of strips from each side near the reel, between the two sides. At the middle of the section, another set of strips is cut or cut from the entire roll. When cutting the sample, be careful not to separate the sheets in a stack of samples or the strips in a set of samples. A sample of g is placed in the container. If the 50g sample volume is too large, a smaller amount of sample may be used, but it should be stated in the test report. The sample of mm, the larger size is tested in the longitudinal direction of the paper, and the sample taken at each position is tested, and the results are reported separately. Min weighing, repeat the above operation, until the difference between the two weighings is not more than 0.1% of the original sample weight, it can be considered to reach constant weight. X (%) is calculated as follows: - the mass of the sample before drying, - the mass of the sample after drying, a. the average value b. the maximum and minimum values ​​for all selected samples c. standard deviation d. test Number of times a. Average b. Maximum and minimum values ​​For each sample selected in accordance with the method specified in 7.1.2 or 7.2.2 c. Standard deviation d. Number of tests e. Sampling position
7.2.1 Determination of moisture content of a batch of samples
Remove the damaged layer on the outside of the reel and discard it. If the amount is less than, remove at least three layers of undamaged layer. If the amount is greater than, at least one more layer is not damaged.
Cut the roll at least 5 times in the transverse direction
Discard the upper and lower sheets of each set of strips and combine the remaining strips to form a sample, which will be no less than 50
7.2.2 Determination of changes in lateral moisture
Select the specimen at least three positions on the reel banner according to the method specified in 7.1.2, and cut the width 50-75 in the transverse direction.
8 test steps
Place the sample in a container that has been dried to constant weight, open the lid of the container, and dry it in a 105+2 oven with the lid. The sample can also be taken out from the container to spread the drying, container and lid. It is also dried in the same oven. When the drying is complete, the container should be covered in the oven. If it is spread out, put the paper strip back in the container and cover it. Move into the dryer and cool 30
9 Calculation of results
Moisture
In the formula:
The test results are accurate to 0.1%.
10 test report
The test report should include the following:
10.1 When determining the average value of a batch of water
10.2 When determining the change in moisture of a flat or reel banner
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