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Why does the national standard describes the allowable error by air dry basis?

For the allowable errors from different laboratories, the air dry basis is very easy to get affected by the moisture changes. The air dry basis from different laboratories have no comparability, that is why we need to use the sample on air dry basis to compare the precision from different laboratories.
What is sampling precision?

Sampling precision is the difference (95%) of average analysis value for the numerous single sampling value.

For article at: Brief Discussion on Sampling Precision
When the strong acid or strong base has splashed in the eyes or on the skin, how to deal with it?

When the strong acid splashed in the eyes or on the skin, please quickly rinse with plenty of water, and then clean with 0.5% sodium bicarbonate solution;

When the strong base splashed in the eyes or on the skin, please quickly rinse with plenty of water, and then clean the eyes with 2% dilute boric acid solution or clean the skin with 1% acetic acid. After the emergency treatment, please go to see a doctor at once.
When do we need to check the precision of coal sample preparation?

1. When the new crusher and divider are mechanically adopted

2. when there is any doubt for sample preparation precision

3. When it is necessary
In the process of fineness determination, what issues we should pay attention to?

1. Sieving needs to be complete. When mechanical sieve shaker is adopted, it is required to brush the sieve bottom regularly according to the operating requirements to prevent the sieve mesh from being blocked by coal powder because it will lead to higher analysis result.

2. After the sieving, use a soft brush to brush the outside part of the sieve mesh carefully without any coal powder loss or any damage to the sieve.

3. The sieve for analysis is required to be calibrated. If the sieve is not qualified, it cannot be used in analysis; once the sieve is loose or the frame gets deformed, the sieve is supposed to be replaced.

4.Technical specification for mechanical sieve shaker must conform to the requirements.
In the process of total moisture determination , what issues we should pay attention to?

1. The sample is required to be kept in sealed container and placed into a cool place.

2. Sampling operations should be fast. It is better to use sealed crusher.

3. Once the coal sample arrives at the laboratory, analyze it at once.

4. Coal sample size for total moisture determination shall not be excessive small. If you need to use finer coal sample, sealed crusher or Two-step Approach is supposed to be used. (Crush the bigger coal sample to determine the external moisture, and then crush the sample into finer sub-sample to determine the internal moisture).

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Why does the national standard describes the allowable error by air dry basis?

What is sampling precision?

When the strong acid or strong base has splashed in the eyes or on the skin, how to deal with it?

When do we need to check the precision of coal sample preparation?

In the process of fineness determination, what issues we should pay attention to?

In the process of total moisture determination , what issues we should pay attention to?