1. Infrared instruments are small in size, wide in measurement range and poor in accuracy, and are suitable for the determination of wood, paper and other materials with moisture content of 5% ~ 9%, with simple structure and low price.
2. Karl Fischer coulometry instruments, the main principle: using the change of conductivity after chemical reaction to calculate, have complex structure, large volume and high determination accuracy, and are suitable for the determination of water content below 1mg (specific weight). It is generally used for the determination of products in chemical, pharmaceutical and other industries that have very strict requirements on moisture, such as anionic polymerization, and the price is relatively expensive.
3. Karl Fischer volumetric method, with simple structure, moderate volume and accuracy, is suitable for the determination of water content from 1 ppm to 1% (volume percentage), and is generally used for the determination of products in chemical industry, medicine and packaging industries with strict requirements on water content, and the price ranges from several thousand yuan to tens of thousands of yuan.
For general industries, when determining the moisture content of solvents such as ethyl acetate, Karl Fischer volumetric moisture analyzer can completely meet the requirements of 2 ~ 1 times a day, and it is economical.
Talking about the selection and operation points of micro-moisture analyzer
1. zui should consider automatic micro-moisture analyzer when choosing. The manual moisture analyzer needs the experimenter to visually inspect the reagent in the glass burette, and it also needs to be manually turned off after reaching the end point, which will bring unnecessary errors because of the delay due to different action habits of each person.
2. When choosing, you should consider purchasing a fully enclosed test system. Bare Karl Fischer reagent absorbs water very easily because of the existence of iodine, and the ethyl ester sample and methanol solvent to be tested should also try to avoid the error caused by the dissolution of water in the air.
3. The service life of metering pump should be considered. Metering pump is a key part of volumetric moisture meter, and Karl Fischer reagent is a highly corrosive reagent. Metering pump made of fluoroplastics and other corrosion-resistant materials should be selected as far as possible to prevent leakage and lead to the scrapping of the instrument.
4. electrode problem. This part belongs to the core part of the instrument, on the one hand, it should have high sensitivity, on the other hand, because it is immersed in the test cell, it is best to choose a high-quality platinum electrode instrument to maintain the electrode life.
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