Questions and Answers
What is the purpose of adding a sampling unit variance correction term to equation (3)?
To account for the variance in sampling units when only some of the elements are sampled and tested (discontinuous sampling)
What is the symbol for the number of sampling units in a batch of coal?
u
When is a special sampling plan required?
When the sampling precision is expressed by coal quality parameters other than ash, or when the required ash precision value is less than the values listed in Table 1, or when a sampling plan has been agreed upon by the interested party.
What is the purpose of the bias test and sampling precision verification according to Appendix C?
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What is specified in Table 1?
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What is the basic sampling program based on?
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What is the purpose of dividing a batch of coal into multiple sampling units?
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What is the minimum mass of the total sample that can be reduced to, according to Table 4?
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What is the formula used to determine the number of coal sampling units?
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Why may sub-samples or sub-samples need to be added during sampling?
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What is the basic sampling unit amount of coal in tons (t)?
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What is the purpose of Table 4 and Table 5?
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What is the consequence of not meeting the minimum mass requirements during sampling?
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What is the formula used to calculate the number of increments when the coal sampling unit is greater than 1000t?
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What is the first step in designing a sampling plan?
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What is the purpose of determining the sampling method?
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What are the three types of sampling modes?
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What is the importance of determining the sampling location?
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What is the purpose of determining the quality parameters?
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What factors affect the determination of sampling precision?
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What is the importance of defining the mass of the primary increment, the post-fractionation sample, and the test sample?
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What is the purpose of outlining the elements included in all sampling plans?
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What is the minimum increment mass, and how is it calculated?
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What is the purpose of Table 6 in the context of coal sampling?
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What is increment average mass, and how is it calculated?
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What are the steps involved in setting up a sampling plan for coal?
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What is the purpose of determining the nominal top size of the coal in the sampling plan?
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What is the role of coal variability in the sampling plan?
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What is the purpose of determining the parameters to be determined in the sampling plan?
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What is the relationship between the minimum sample mass and the increment mass?
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What is the purpose of determining the sampling unit variance in coal sampling?
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What are the two methods used to determine the sample preparation and testing variance?
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What is the formula used to calculate the sample and laboratory variance in Method one?
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What is the initial assumption of the sample preparation and testing variance in the absence of data?
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What is the purpose of calculating the initial sampling units?
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What is continuous sampling, and how is it used in coal sampling?
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Why is it important to determine the sample preparation and laboratory variance in coal sampling?
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What is the significance of the number of sampling units and increments in coal sampling?
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Study Notes
Sampling Principles
- Discontinuous sampling requires a sampling unit variance correction term to be added to equation (3)
- VSPT and PL calculations are performed according to equations (6) and (7)
Basic Sampling Scheme
- The sampling principle is based on the provisions of this standard, and special sampling plans can be devised in certain cases
- The sampling precision is expressed by the coal quality parameters other than ash
- The required ash precision value is less than the values listed in Table 1
- A sampling plan has been agreed upon by the interested party
Sampling Unit and Increment
- The total precision (ash, Ad) of sampling, preparation, and testing of coal and other coal washing is specified in Table 1
- The number of increments when the coal sampling unit is greater than 1000t is calculated according to formula (8)
- The sampling unit of coal amount of more than 1000t, the number of increments is calculated according to formula (8)
- A batch of coal can be used as a sampling unit, and can be divided into m sampling units according to formula (9)
Determination of Number of Coal Sampling Units
- The precision of sampling is better when a batch of coal is divided into multiple sampling units
- The minimum mass of the total sample is specified in Table 4 and Table 5 for general coal samples, total moisture coal samples, and particle size analysis coal samples
Sample Quality and Increment Mass
- The minimum increment mass is calculated by formula (10), but at least 0.5kg
- The minimum increment mass is specified in Table 6 according to the nominal top size of the coal sampled
- The increment average mass is calculated according to equation (11)
Design Special Sampling Scheme
- The basic procedure to set up the sampling plan includes:
- Determining the coal source, batch, and parameters to be determined
- Determining the nominal top size of the coal, the minimum mass of the total sample, and increments
- Determining or assuming the required precision and coal variability
- Determining the number of sampling units, increments, and sampling method
- Determining the sampling mode, sampling base, and location
- Determining the method of combining the increments and sampling method
Design of Sampling Procedures
- The design of the sampling plan is based on the actual situation and includes the operating instructions for implementing the sampling
- The operating instructions should be simple, easy to understand, feasible, and fully understood by the sampler
- The type of sample is determined according to the purpose of sampling (technical evaluation, process control, quality control, or commercial purposes)
- Quality parameters are determined according to the sampling purpose and the type of sample
Determining the Precision of Sampling
- Sampling precision is determined according to the sampling purpose, sample type, and requirements of the parties to the contract
- The sampling unit variance is determined based on a similar sampling scheme for coal
- The sampling unit variance can be initially assumed to be 5 for ash content, and checked after sampling
Sample Preparation and Laboratory Variance Determination
- One of the following methods can be used to determine the sample preparation and testing variance:
- Direct determination using Method 1 or Method 2
- Determination based on similar procedures for the determination of coal in similar samples
- In the absence of data, the sample preparation and testing variance can be initially assumed to be 0.2 for ash content, and checked after preparation and testing
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Description
Learn about the importance of adding a sampling unit variance correction term when using discontinuous sampling methods, and how to perform VSPT and PL calculations.