GB/T 6679-2003General rules for sampling solid chemical products (English PDF)

3.1 Sample types of solid chemical products

Sample types include partial sample, directional sample, representative sample, cross-sectional sample and geometric sample.

The sample type shall be determined based on the sampling purpose, sampling conditions, and material conditions (batch size, geometric state, particle size, uniformity, and variability distribution of characteristic values).

3.2 Basic requirements for samples

3.2.1 Sampling inspection is an inspection method that evaluates and judges the quality of the overall material by inspecting samples. The sample must be representative of the overall material characteristics.

3.2.2 The amount of samples collected shall be able to represent all the characteristics

3.4 Sampling plan

3.4.1 A sampling plan must be developed before sampling.

3.4.2 The purpose of developing a sampling plan is to obtain representative samples of the overall material at the lowest cost and within the allowable sampling error range.

3.4.3 The factors that must be considered when developing a sampling plan are mainly the sampling purpose, the difference in overall material characteristic values, the allowable sampling error, and the packaging and transportation method of the material (according to the provisions of GB/T 6678).

3.4.4 The theoretical basis for formulating the sampling plan is specified in GB/T 6678.

3.5 Others

3.5.1 Since there are many types of solid chemical products and the sampling conditions are ever-changing, the sampling shall be based on the basic principles and methods specified in this standard, and the optimal sampling plan and sampling techniques shall be selected according to the actual situation and possibility.

4.1 Principle for selecting sampling techniques

4.1.1 The principles for selecting sampling techniques shall be based on the shape, particle size, quantity, difference in material characteristic values, and state (stationary or moving) of the materials to be sampled.

4.2 Basic requirements for samplers and sample dividers

4.2.1 The materials used must not have any reaction with the materials to be sampled, and must not cause contamination, delamination or loss of the materials to be sampled.

4.2.2 It shall be clean, dry, easy to use, clean, maintain, inspect and repair.

4.2.3 Any sampling device (especially automatic sampler) shall be subject to a feasibility test before formal use.

4.2.4 For the types of samplers and sample dividers, see Appendix A, Appendix B, Appendix C, Appendix D and Appendix E.

4.3 Sampling method

4.3.1 Sampling of powders, granules and small crystals

4.3.4 Sampling of solids that can be cut

Use a knife or other suitable tool (such as a metal wire) to take a cross-sectional sample or a geometric sample of a certain shape and weight from a certain part of the material.

4.3.3 Sampling of massive materials

4.3.3.1 Stationary materials

Respectively take partial samples, directional samples, geometric samples or representative samples according to the material conditions. They are separately described as follows.

a) Partial sample

4.3.3.2 Moving materials

Take cross-sectional samples randomly or at certain time intervals.

If the material can be crushed, take samples according to the method in 4.3.1 after crushing.

4.3.5 Solids requiring special processing

4.3.5.4 Sampling of solids that react with the surrounding environment

4.3.5.5 Reactive or unstable solids

Such solids shall be sampled in accordance with relevant standards and regulations.

5.1 Purpose of sample preparation

Obtain the optimal amount of samples from a larger amount of original samples that can meet the inspection requirements and whose properties to be measured can represent the overall material characteristics.

5.2 Principle of sample preparation

5.3 Sample preparation stage

It generally includes three stages. crushing, mixing and reduction. The operation shall be repeated one or more times depending on the situation until the final sample is obtained.

5.4 Sample preparation techniques

Crushing, mixing, and reduction can be carried out by manual or mechanical methods according to the situation and possibility.

5.4.1 Crushing

5.4.2 Mixing

5.4.2.1 Manual method

Depending on the size of the sample, use an appropriate hand tool (such as hand shovel, etc.) to mix the sample.

5.5 Final sample quantity and storage

5.5.1 The final sample quantity shall meet the needs of testing and preparation. Divide the sample into two generally equal parts. One for testing and one for reference. The amount of each sample shall be at least three times the amount required for testing.

5.5.2 Packaging materials and appropriate packaging forms that are inert to the sample shall be selected based on the sample and storage time.

5.5.3 Sample packaging containers shall comply with the provisions of GB/T 6678.

5.5.4 The container shall be labeled with the specified content immediately after loading (according to the provisions of GB/T 6678).