The main factors of measurement uncertainty

In order to confirm the major factors influencing the factors, a detailed survey was conducted on the personnel of different types of work. According to the factors of inaccurate measured values, a careful analysis of various causes was conducted to find the main reasons. The results of the survey showed that the main reasons were: There are 10 below.

(1) The quality of coal sample preparation affects the results of sulfur determination. The purpose of preparation of coal sample is to prepare coal samples for representative analysis by crushing, mixing, and reducing processes. Coal samples shall be prepared in time according to the standard sample preparation system. If they are not operated according to the regulations, if they are not reduced proportionately and brought to an air-dry state, there will be no magnets to suck the iron scraps in the coal samples, without crushing. If the coal sample is less than 0.2mm, accurate measurement results will not be obtained. Therefore, the quality of the coal sample preparation is a factor.

(2) The waste sample and standard sample of the sulfur measuring instrument are not properly selected. Each time the instrument is turned on, a waste sample should be made before the sample is detected. After that, the sample is used. After the sample is qualified, the sample is tested again. If the sulfur content of all the standard samples is high and the sulfur content of the test sample is low, the measurement results will be inaccurate due to the non-conformity of the calibration coefficients. Therefore, the improper selection of waste samples and standard samples of the sulfur measurement instrument is the cause.

(3) The sample size of the test coal is not uniform, and the representativeness is not strong enough; because the coal particle size and ash content are all very uneven, when the particle size of the sample is not uniform, the precision of the measurement result will be poor. Therefore, in the preparation of analytical samples, it must be fully milled to improve its uniformity. Weigh the sample and spread it evenly. Samples are not representative, resulting in deviations from the results or the measured values ​​are not stable. Therefore, the size of the coal samples is not uniform and the representativeness is not strong enough.

(4) The experimental process of sulfur measurement is highly normative. If it is not operated according to national standards and regulations, it will inevitably affect the accuracy of the data and cause damage to the instrument. Therefore, there is no reason to perform sulfur measurement strictly according to the national standard.

(5) There are many complex components in the sulfur analyzer system. Failure of each component will affect the normal use of the instrument and the accuracy of the data. Therefore, the sulfur analyzer is unstable in operation and the system is faulty.

(6) The quality of laboratory personnel's business quality directly affects the level of operation and use of instruments and equipment, and affects the efficiency and longevity of the instrument. Therefore, the quality of laboratory personnel's business quality is a factor.

(7) During the test, when the melting plate of the electrolytic cell has ash or black deposits, it will cause blockage of the gas path and make the measured result low; the indicator electrode of the electrolytic cell is also susceptible to contamination due to prolonged exposure to air. Therefore, the electrolyzed cell was not cleaned in time.

(8) The electrolysis cell is commonly used in the analytical work potassium iodide potassium bromide glacial acetic acid distilled water configuration, stored in a cool and dark place. After multiple determinations of the sample, sulfuric acid is generated in the electrolyte, which also results in a low measurement result. Therefore, the electrolyte is not replaced regularly.

(9) Some of the replacement parts of the instrument are of poor quality. The performance of the sulfur measurement instrument depends on the quality of the entire instrument. Individual replacement of the instrument parts may affect the use of the instrument, but the impact is not significant and may pass the inspection of the incoming goods. Avoidance, so the poor quality of some of the replacement parts of the instrument is an important factor.

(10) The laboratory environment of the sulfur measurement instrument is poor, and the laboratory work environment mainly refers to the laboratory temperature, humidity, and the influence of waste gas and waste residue discharged during the test on the test environment. Nitrogen oxides and sulfides produced in industrial analysis directly affect the test environment. The accuracy of the sulfur measurement results, therefore, the general sulfur analyzer should be placed in a separate room with control of temperature, humidity, and exhaust, and the laboratory lacks only the means to control the humidity, so it is a non-essential factor.