What is the National Standard TCVN 1693:2008 (ISO 18283: 2006) on Hard coal - Manual sampling in Vietnam?
Vietnam: What is the scope of application of the National Standard TCVN 1693:2008 (ISO 18283:2006)?
Pursuant to Section 1 of the National Standard TCVN 1693:2008 (ISO 18283:2006), the scope of application is defined as follows:
- This standard specifies the basic terms used in manual sampling of coal and coke and describes the general principles of sampling. This standard specifies the procedures and requirements for preparing sampling diagrams, sampling methods, manual sampling methods, sampling tools, sample handling and preservation, sample preparation, and sampling documentation.
- This standard applies to manual sampling from flowing fuel streams. Manual fuel sampling in a static state is described in Appendix B, but this method does not provide representative samples, and this should be clearly stated in the sampling report.
- This standard does not apply to the sampling of brown coal and lignite, as described in ISO 5069-1 and ISO 5069-2. This standard does not apply to sampling from coal piles, as described in ISO 14180. The mechanical sampling of coal and coke is specified in ISO 13909 (all parts).
What is the National Standard TCVN 1693:2008 (ISO 18283: 2006) on Hard coal - Manual sampling in Vietnam? (Image from the Internet)
What should be noted when manually sampling coal and coke in Vietnam?
The National Standard TCVN 1693:2008 (ISO 18283:2006) highlights the following points:
- Sampling may involve materials, equipment, and hazardous conditions.
- Within the scope of this standard, safety issues related to the use of TCVN 1693:2008 are addressed.
- The responsibility of the user of this standard is to establish appropriate rules regarding health and safety and to define permissible limits before use.
What are the terms to be familiar with in the National Standard TCVN 1693:2008 (ISO 18283:2006)?
Pursuant to Section 3 of the National Standard TCVN 1693:2008 (ISO 18283:2006), the terms to be familiar with are as follows:
- Air-drying: The process of bringing the moisture content of a sample into equilibrium with the atmospheric conditions in the region where the reduction and division of the sample continue to be carried out.
NOTE: Air-drying is done to bring the sample moisture content in line with the applicable environment for coal. Coke is typically air-dried for convenience in sample preparation.
- Bias: The systematic error that leads to a consistently higher or lower average value of a continuous series of results compared to the results obtained using a standard sampling method.
- Common sample: A sample collected for expected multiple uses.
- Continuous sampling: Sampling from successive small batches so that individual samples are taken at regular intervals regardless of the sampling time.
- Divided increment: The portion of a sample obtained from dividing a single sample to reduce the sample mass.
NOTE: Such division may be performed with or without size reduction.
- Fixed-mass division: A sample division method in which the retained mass is predetermined and not dependent on the feed mass.
- Fixed-ratio division: A sample division method in which the division ratio is predetermined, meaning the retained sample mass is a fixed ratio of the feed mass.
- Fuel: Coal or coke.
- General analysis test sample: A sample prepared to pass through a sieve mesh size of 212 μm according to ISO 3310-1, used to determine most chemical parameters and some physical properties.
- Increment: The portion of fuel obtained by a sampling operation using a sampling tool.
- Intermittent sampling: Sampling only from specific small batches of fuel.
- Lot: A certain quantity of fuel that must be considered for quality determination
NOTE: A lot can be divided into smaller lots.
- Manual sampling: The process of taking individual samples by manpower.
- Mass-basis sampling: The process of taking individual samples where the sampling position from the fuel stream is determined based on a mass range of the stream and a fixed mass of the individual sample.
- Mechanical sampling: The process of taking individual samples using mechanical means.
- Moisture sample: A sample taken specifically for the purpose of determining the total moisture content.
NOTE: For coke, this sample can also be used for general analysis.
- Nominal top size: The size of the smallest sieve opening in a series of R20 sieves [see TCVN 2230 (ISO 565), square mesh] that does not retain more than 5% of the sample.
- Physical sample: A separate sample taken to determine physical characteristics, such as strength indices or size distribution.
- Precision: The closeness of agreement between independent test results obtained under specified conditions.
+ NOTE 1: Precision is often expressed using a measure of precision, such as the standard deviation.
+ NOTE 2: Precision may be determined with a large precision and therefore the standard deviation of some tests on the same small lot may be low; but such results are only accurate if they are unbiased.
- Primary increment: A single sample taken at the first stage of sampling, before the sample is divided and/or reduced.
- Random sampling: The process of taking individual samples randomly by mass or random time intervals.
- Replicate sampling: The process of taking individual samples at regular successive time intervals into different containers to obtain two or more samples of equal mass.
- Sample: An amount of fuel that represents a large mass of fuel to be assessed for quality.
- Sample division: The process of preparing a sample whereby the sample is divided into separate and representative portions.
- Sample preparation: The process of making a sample meet the requirements for analysis or testing.
NOTE: Sample preparation includes mixing, size reduction, sample division, and sometimes air-drying of the sample and can be performed in multiple stages.
- Sample reduction: The process of preparing a sample whereby the particle size of the sample is reduced by crushing or grinding.
- Size analysis sample: A separate sample taken for size analysis.
- Standard deviation: The square root of the variance.
- Stratified random sampling: The process of randomly taking a single sample in which a specified mass or time interval corresponds to the mass or time interval for sampling.
- Sub-lot: A portion of a lot that is required to be tested.
- Systematic sampling: The process of taking individual samples from a mass or time interval at regular intervals according to a predetermined plan.
- Test sample: A sample that has been prepared to meet the requirements of a specific test.
- Time-basis sampling: The process of taking individual samples in which the position of each individual sample taken from the fuel stream is determined by a time interval and the sample mass is proportional to the flow rate at the time of sampling.
- Unit mass: The amount of material determined during the sampling process (usually the primary increment).
- Variance: A measure of dispersion, being the sum of the mean square deviations of the observed values divided by the number of observations minus one
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