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GB/T8618—2001
This standard is a revision of GB/T8618—1988 "Sampling Method for Main Products of Salt Industry". This standard adopts ROCT13685—1984 "Test Method for Edible Salt" in a non-equivalent manner. JISK1051—1985 "Sampling Method for Industrial Salt". This standard has been revised to add sampling for iodine content test of standard type edible salt for measurement of defective product rate, and supplement and modify the sampling and expression of main products of salt industry in the original standard. This standard will replace GB/T8618—1988 from the date of implementation. Appendix A of this standard is the appendix of the standard.
This standard is proposed by the State Bureau of Light Industry.
This standard is under the jurisdiction and interpretation of the National Sea and Lake Salt Standardization Center. The drafting unit of this standard: National Sea and Lake Salt Standardization Center. The main drafters of this standard: Liu Zhida, Chen Sujuan, Wang Zhibin. 1 Scope
National Standard of the People's Republic of China
Sampling methods of the main products in the salt industry
Sampling methods of the main products in the salt industryGB/T8618—2001
Replaces GB/T8618—1988
This standard specifies the sampling of technical indicators for the main products of the salt industry, such as edible salt, industrial salt, industrial potassium chloride, industrial magnesium chloride and industrial bromine, when they are delivered, and specifies the standard sampling method for the rate of non-conforming products and the principle of accepting batch products for the iodine content test of edible salt.
This standard is applicable to the sampling of the delivery and supervision inspection of the main products in the salt industry. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard by reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and the parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T8053-1987 Standard for measurement of defective product rate Single sampling inspection procedures and tables Part I
3 Sampling of major products in the salt industry
3.1 General provisions
3.1.1 The equipment, tools and sample containers used for sampling and sample preparation must be kept clean, sturdy and durable. 3.1.2 Sampling and reduction must be carried out strictly in accordance with the methods specified in this standard. 3.1.3 If foreign matter is mixed into the product, remove it before sampling. 3.1.4 The samples should be properly kept. After the inspection report is issued, the samples should be kept for one month for inspection. 3.1.5 Pay attention to safe operation during the entire sampling process. 3.1.6 In principle, large sample reduction should be carried out indoors to avoid the reduction of samples being affected by climatic conditions, and pay attention to being as fast as possible. 3.2 Explanation of terms
3.2.1 Sampling unit
A certain amount of material with boundaries, the boundaries may be tangible, such as a container, or imaginary, such as a time interval in the material flow.
3.2.2 Batch and batch
All packages of the same grade produced by the same processing method in one delivery constitute a batch. The number of unit products contained in a batch is called a batch.
3.2.3 Incremental sample
A sample taken from a point or a part of a batch of products according to regulations. 3.2.4 Bulk sample
A sample composed of all incremental samples of a batch of products. 3.2.5 Prepared sample
Approved by the State Administration of Quality and Technical Supervision on April 8, 2001 and implemented on October 1, 2001
GB/T8618-2001
A sample prepared from each incremental sample or bulk sample according to the prescribed sample preparation method. 3.2.6 Reduced sample
Representative sample taken from the bulk sample. 3.2.7 Laboratory sample
Sample sent to the laboratory for inspection and testing. 3.2.8 Spare sample
Sample prepared at the same time as the laboratory sample. In case of dispute, it can be accepted by the relevant parties as a laboratory sample. 3.2.9 Standard deviation (8)
The sum of the squares of the differences between the measured values (a) and the average value () divided by the square root of the number of measurements (m) minus 1. 3.2.10 Quality fluctuation standard deviation (Sw) The standard deviation of the fluctuation of the main component quality characteristics between the samples within the batch. According to the size of the S value, the quality fluctuation of various products can be divided into three types: large, medium and small.
3.3 Determination of the number of samples
3.3.1 Determine according to the prescribed method (suitable for products with small variability of material characteristic values and basically uniform) The number of sample units to be selected shall be determined according to the number of units contained in the population. When the number of units of the overall material is greater than a certain number as determined by the table, the number of samples shall be taken as multiples of the cube root of the number of overall units, that is, f×N (N is the number of overall units, f is the coefficient). If a decimal is encountered, it shall be rounded up to an integer.
3.3.2 Determine by calculation according to the statistical formula (suitable for products with large variability of material characteristic values) When the sample characteristics constituting the population obey the normal distribution, they can be estimated according to the statistical formula based on the given parameters. The minimum number of basic batch samples is calculated according to formula (1):
Where: n——number of samples;
Sw——standard deviation of the principal component measurement values of samples between samples within the batch; .(1)
E——maximum allowable sampling error, which means the maximum allowable error between the average value of m samples and the average value of the whole;
t——probability coefficient, the confidence probability of this standard is set at 95%, and the probability coefficient is 1.96. The calculated minimum number of samples can only be increased but not decreased. 3.3.3 Calculation of standard deviation of batch product quality fluctuation The standard deviation of each batch of products with similar batches can be calculated according to formula (2) based on product quality data to determine the category of quality fluctuation. When the quality fluctuation of the product cannot be determined, sampling is applicable for the case of "large" quality fluctuation. :-)
Where: S.——standard deviation of quality fluctuation of each batch of products; ——single measurement value;
, —arithmetic mean of single measurement value: —number of samples in each batch.
3.3.4 Determination of the number of incremental samples when the batch size increases
When the batch size increases, the number of incremental samples to be taken shall be calculated according to formula (3): Actual batch size (tons or pieces)
n1=n×original batch size (tons or pieces)
Where: n1——the number of incremental samples to be taken when the batch size increases; n——the number of incremental samples to be taken for the basic batch size. bzxZ.net
(3)
3.4 Sampling
3.4.1 Types of sampling
GB/T8618—2001
When incremental samples are taken within the batch, any of the following methods or a combination thereof may be used. 3.4.1.1 Belt conveyor sampling: When the batch is transported by a belt conveyor, incremental sampling is used. 3.4.1.2 Bag and box sampling: When the batch is delivered in bags or boxes, incremental sampling is used. Truck sampling: when the batch is delivered by truck, the method of taking incremental samples from it. 3.4.1.3
3.4.1.4 Truck sampling: when the batch is delivered by train, the method of taking incremental samples from it. 3.4.1.5 Ship sampling: when the batch is delivered by ship (barge, ship), the method of taking incremental samples from it. 3.4.1.6 Jar sampling: when the batch is delivered by jar, the method of taking incremental samples from it. 3.4.2 Method of taking incremental samples
When delivering in batches or for supervisory inspection, no matter the product is in a static or flowing state, the first incremental sample shall be taken randomly, and then incremental samples shall be taken at a certain distance or a certain time according to the determined number of incremental samples. When the product in the bag (or box) is a small package bag, a sample shall be taken from the small bag. 3.4.3 Sample quantity
The sample quantity of the incremental samples taken according to the number of incremental samples shall meet the following requirements after mixing and reduction. 3.4.3.1 Meet the needs of secondary inspection and verification. 3.4.3.2 The sample volume of edible salt, industrial salt, potassium chloride and magnesium chloride is greater than 1000g, and the volume of industrial bromine is greater than 100mL. 3.4.3.3 Meet the needs of spare samples.
3.4.4 Sampling of edible salt
Edible salt includes refined salt, crushed washing salt and sun-dried salt, which are packaged in bags (or boxes) and are sampled according to the number of samples listed in Table 1. Table 1 Minimum number of samples for edible salt
Batch, bag
<100
101~200
201~300
301~500
501~1000
1001~2000
2001~3000
3001~5000
Refined salt
Sw≥0.15%
Crushed washing salt, sun-dried salt
When sampling, insert the sampler into the middle of the bag to take the sample, and the weight of each sample is about 100g. The samples taken are mixed evenly and divided into quarters to obtain the divided samples.
3.4.5 Industrial salt sampling
Industrial salt includes processed salt from different salt regions, and its batches can be delivered in bags, boxes, vehicles, ships, belt conveyors, etc. The quality fluctuation of industrial salt is expressed by the standard deviation of the systematic sampling of the main content of sodium chloride. When refined salt is used as industrial salt, its sampling is in accordance with the provisions of refined salt in edible salt.
3.4.5.1 Classification of quality fluctuation
Classification of industrial salt quality fluctuation is shown in Table 2.
Table 2 Classification of industrial salt quality fluctuation
Classification of quality fluctuation
Sw, %
3.4.5.2 Belt conveyor sampling
Sampling is taken when the belt conveyor transports industrial salt. The minimum number of samples is shown in Table 3. Small
Number of samples
Batch, t
≤500
501～1000
1001~2000
2001~3000
3001~5000
500110000
GB/T8618—2001
Table 3 Minimum number of samples taken for industrial salt on belt conveyor
Take samples at regular intervals at any position or drop point perpendicular to the direction of belt travel, and the weight of each sample is about 300g. Mix the samples evenly and divide them into quarters to obtain the divided samples. 3.4.5.3 Bag sampling
The minimum number of samples taken for bagged industrial salt is shown in Table 4. Table 4 Minimum number of bags for bagged industrial salt
Number of samples, bag
Batch, t
201500
501~1000
1001~2000
2001~3000
3001~5000
Use the sampler to insert into the middle of the bag to take samples, and the weight of each sample is about 200g. The samples taken are mixed evenly and divided into four parts to obtain the reduced samples.
3.4.5.4 Sampling on trucks
In the case of bulk industrial salt in trucks, one truck is selected for sampling for every 20t, and the minimum number of samples is shown in Table 5. Table 5 Minimum number of samples taken by selected trucks Number of samples
Truck load, t
The sampling points should be evenly distributed at various locations of the truck and arranged according to Figure 1. Remove the surface layer, insert the sampler vertically into the depth of 0.5m to take the sample, and the weight of each sample is about 300g. The samples taken are mixed evenly and divided into four parts to obtain the subsamples. 1
Figure 1 Sampling distribution points of trucks
3.4.5.5 Sampling on trucks
GB/T8618—2001
The minimum number of samples taken from each truck loaded with industrial salt is shown in Table 6. Table 6 Minimum number of samples of industrial salt taken from a truck Batch size
Number of samples
A truck
Load, t
Below 60
Below 200t
Above 200t
The sampling points on the truck should be evenly or cyclically distributed on the diagonal line of the car (Figure 2), and the points at both ends should not be less than 0.5m from the corner of the car. Remove the surface layer, and note that the particle size ratio of the sample is roughly consistent with the particle size distribution in the car, and the mass of each sample is about 300g. The samples taken are mixed evenly and divided into quarters to obtain the divided samples. 12
Figure 2 Sampling distribution points of trucks
3.4.5.6 Sampling in ships (barges)
The salt loaded on a ship (barge) is regarded as a batch, and the samples are taken during loading (or unloading). The first sample is taken at the beginning of loading (or unloading), the second sample is taken when the ship (barge) loads (or unloads) a quarter of the whole batch of salt, and the third sample is taken when the ship (barge) loads (or unloads) three quarters of the whole batch of salt. Each sampling point is taken from ten different points of the ship (barge). A total of 30 samples are taken, each with a mass of about 300g. All samples are mixed evenly and divided into quarters to obtain the divided samples. 3.4.6 Sampling of industrial potassium chloride
3.4.6.1 Classification of quality fluctuation
The magnitude of quality fluctuation of industrial potassium chloride is expressed by the standard deviation of the measured value after sampling according to the main content of potassium chloride component. The classification is shown in Table 7. Table 7 Classification of quality fluctuation of industrial potassium chloride
Classification of quality fluctuation
3.4.6.2 Sampling of bags
The minimum number of samples taken for bagged industrial potassium chloride is shown in Table 8.
Table 8 Minimum number of bags for industrial potassium chloride
Number of sample portions, bag
Batch, t
≤100
101~200
201～300
301~500
501～1000
1001～2000
GB/T8618—2001
Use a sampler to insert into the middle of the bag to take samples, and the weight of each sample is about 200g. The samples taken are mixed evenly and divided into four parts to obtain the subsamples. 3.4.7 Sampling of industrial magnesium chloride
3.4.7.1 Classification of quality fluctuation
The size of the quality fluctuation of industrial magnesium chloride is expressed by the standard deviation of the measured value after sampling according to the main content of industrial magnesium chloride components. The classification is shown in Table 9.
Table 9 Classification of quality fluctuation of industrial magnesium chloride
Classification of quality fluctuation
3.4.7.2 Sampling of bags
The minimum number of samples taken for bagged industrial magnesium chloride is shown in Table 10. Medium
Minimum number of bags
Number of samples, bag
Batch, t
201~500
501~1000
1001~2000
2001~3000
3001~5000
Use a small shovel to scoop the granular or flaky industrial magnesium chloride product at a depth of 0.2m from the surface, and the weight of each sample is about 200g. The samples taken are put into a large plastic bag, mixed evenly, and divided to obtain the divided samples. 3.4.8 Industrial bromine sampling (limited to jars)
The minimum number of samples for industrial bromine is shown in Table 11. Table 11
Minimum number of jars for industrial bromine
Batch, jar
51~100
101~200
201～300
Select the minimum number of jars
When the batch is greater than 300 jars, take the cube root of the total number of jars in each batch, that is, the number of samples is equal to N (N is the total number of jars in each batch). If there is a decimal, round it up to an integer.
Use a glass sampler to insert the middle two-thirds of the jar to take the sample. The capacity of each sample is about 50mL, and the sample is mixed evenly. Part II
4 Sampling for iodine content test of edible salt
General provisions
This method is limited to sampling for iodine content test. The iodine content of each batch of products is determined by the results of a single random inspection. 4.2 Terms and symbols
4.2.1 Terms
4.2.1.1 Unit product
GB/T8618—2001
The basic unit of product division for the purpose of implementing sampling inspection. 4.2.1.2 Sample
A number of incremental samples taken from a batch of products constitute a sample. 4.2.1.3 Inspection batch (lot)
Same as 3.2.2.
4.2.1.4 Sampling inspection once
Decide whether to accept the batch based on the inspection results of the sample taken once. 4.2.1.5 Acceptable quality
In sampling inspection, it corresponds to a certain, higher probability of acceptance, and is considered to be satisfactory. 4.2.1.6 Limit quality
For isolated batches, for sampling inspection, it is limited to a certain quality level with a low probability of acceptance. 4.2.1.7 Variable sampling inspection
The process of extracting a certain number of unit products from a batch according to a specified sampling plan, obtaining their quality characteristic values by measurement, testing or other methods, comparing them with the quality requirements, and judging whether the batch of products can be accepted. 4.2.1.8 Producer's risk
For a given sampling plan, the probability of rejection when the batch quality level (defective product rate) is a specified acceptable value. 4.2.1.9 User's risk
For a given sampling plan, the probability of acceptance when the batch quality level (defective product rate) is a specified unsatisfactory value. 4.2.1.10 Standard sampling inspection
In order to protect the interests of both production and users, the sampling inspection that fixes the producer risk and the user risk to a specific value. 4.2.1.11 Quality statistics
A function composed of specification limits, sample mean and batch standard deviation, used to judge whether the batch can be accepted. 4.2.1.12 Acceptance constant
In the sampling criteria for metrological acceptance, a constant determined by the acceptable quality level and sample size used to decide whether a lot is acceptable. 4.2.1.13 Bilateral specification limits
Specify the maximum and minimum limit values allowed for the quality characteristics of qualified products. 4.2.2 Symbols
This standard uses the following symbols:
U: upper specification limit.
L: lower specification limit.
P: batch defective rate.
Po: acceptable quality level when the batch defective rate is the quality indicator. P1: limit quality level when the batch defective rate is the quality indicator. α: producer risk.
β: user risk.
n: sample size.
2: unit product quality characteristic value in the sample, indicating the unit product quality characteristic value. : sample mean.
a: standard deviation of batch quality characteristic values, referred to as batch standard deviation. 7
Qu: quality statistic of the upper specification limit.
QL: quality statistic of the lower specification limit.
k: Acceptance constant.
4.3 Sampling plan
GB/T8618—2001
This standard is a metrological standard type single sampling inspection method standard, with the batch defective rate as the quality indicator. The plan is applicable to inspection batches whose product quality characteristics are expressed as measured values and obey or approximately obey the normal distribution. 4.3.1 Plan design
The plan stipulates that the production risk α=0.05 and the user risk β=0.10 are set according to the quality characteristics of iodized salt products and batch standard deviation. U=50.0,L-20.0,P. =5%,P1-25%
According to the table of GB/T8053, we get: n=9, =1.114.3.2 Judgment rules
If Q>k and QL≥k, then the batch of products is qualified. If Qu
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