How to solve the error existing in the measurement process of the moisture analyzer
When the moisture analyzer tests the moisture content and solid content in the sample, there is a certain error with the results of the provided moisture test report. Then, how to solve the error existing in the measurement process of the moisture analyzer.
1. After multiple measurements of the same sample by different types of moisture analyzers, the measurement results are all within the normal error range, so doubts about the accuracy of the instrument itself and other factors are ruled out.
2. The user cannot judge whether there are other volatile solvents besides water in the tested sample.
To sum up, the error in our testing process of the user's sample is basically because the user's sample contains other volatile solvents in addition to moisture. At the same time, according to the different test temperatures, the moisture value varies Variations will occur.
So how to effectively avoid errors in the measurement process?
We know that the testing principle of the moisture analyzer is the heating and weight loss method, which means that the moisture in the sample is effectively volatilized after the instrument is heated to a certain temperature, so that the moisture content of the sample can be calculated according to the calculation function of the electronic balance. The result and accuracy of the moisture value are determined by the accuracy of the electronic balance. Of course, the speed and uniformity of the heating method also greatly affect the accuracy of the sample moisture test. At present, because the speed and uniformity of lamp heating are more stable than infrared heating and it is not easy to cause the sample to be burnt, so the moisture analyzer is gradually promoted in the market due to its high quality and high cost performance. So first of all we have to choose high-quality high-precision.
Secondly, the samples must be tested in strict accordance with the operating instructions of the moisture meter. The high-precision moisture meter has quite high requirements on the environment and operation.
1. The surface of the instrument should be flat and not deformed when pressed. Because in the process of pressing the table top, due to the flexibility and elasticity of the table top, slight deformation will occur, and if the instrument is working at this moment, it will be affected;
2. Before the instrument works, it must be preheated, and it will be tested for about 20 minutes after starting up;
3. Make sure that there are no air conditioners, windows, electric fans, etc. around the instrument, so as to avoid the instrument being affected by the wind. In the daily test process, if we use our mouth to blow lightly on the instrument, it will also cause changes in the weighing weight. Not to mention the wind caused by air conditioners, fans, etc.
4. Ensure that the instrument has been calibrated with weights before use;
If there are other volatile solvents in the measured sample, we will also volatilize the volatile solvents while heating the sample to volatilize the water, so the weight loss does not represent the exact content of water, so, at this time, It is inaccurate to measure the moisture of the sample by using the method, the higher the volatile solvent content, the greater the error. In this case, we recommend that users use the Karl Fischer coulometric method, that is, the Karl Fischer trace moisture analyzer to test the moisture of the sample. Since the Karl Fischer reagent only produces a redox chemical reaction on moisture, it effectively avoids other solvents. Effect on the moisture content of the test sample. The results tested by the Karl Fischer chemical method are more accurate, and are suitable for use by manufacturers and research institutes with trace amounts of water or high precision requirements. Of course, different methods can be adopted depending on the properties of the solid sample. If the sample is dissolved in methanol, it is relatively convenient to use the volumetric method. If the solid sample does not dissolve in methanol, use the coulometric method and install a solid gasifier in conjunction with it.
