The laser particle size analyzer is recognized as the most advanced and fastest particle testing instrument in the world. There are many domestic and foreign manufacturers of laser particle size analyzers. The product types are also numerous. How can one choose a laser particle size analyzer suitable for it?

First, understand your own needs

The items that need to be clarified are as follows:

(1) According to the amount of money that can be controlled, determine whether the selected object is imported equipment or domestic equipment: the price of general imported equipment is more than 400,000 yuan. Domestic product prices range from a few tens of thousands to several hundred thousand.

(2) According to the nature of the measured sample, determine whether to purchase dry or wet particle size analyzer: The laser particle size analyzer is divided into dry and wet methods, if it can find suitable dispersion medium (water or other liquid) can not If any reaction occurs in the measured sample, a wet particle size analyzer is recommended. The test results are stable and inexpensive. If the sample is of a special nature, it is difficult to find a suitable dispersion medium. A dry particle size analyzer is recommended.

(3) According to the approximate distribution range of the test sample, select the instrument type that suits the test range of your own sample: The larger the test range, the higher the price. In general, if you choose a device that is slightly wider than the sample distribution range. Most of the laser particle size analyzers on the market span 3-4 orders of magnitude, but most industrial test samples are distributed within only one order of magnitude. If the sample distribution range is narrow and the ultra-wide-range test range is selected, it is equivalent to weighing scales. A bean will reduce the accuracy. Domestic manufacturers have developed a product for binning test, which can adjust the gear according to the conditions of the sample and solve the problem to some extent.

(4) According to the use, select the type of particle size analyzer: users should not blindly follow the trend, select high-end models, if it is only put into the factory for routine product testing, you do not need to buy the latest type of product, old products often after years of improvement, The structure is mature, the test effect is relatively stable, and the price is cheap. If the test task is relatively heavy, you should choose an automated smart product that can greatly reduce the tester's workload. Most high-end products are prepared for research clients such as universities or research institutes. Most of these products are widely distributed, with high precision and complicated structures, and they are often expensive.

Second, choose a technical strength of the manufacturers

Such instruments as laser particle size analyzers are relatively high-tech instrument products. They require high technical strength from manufacturers. Before selecting products, they should first select manufacturers. Generally, they have a technical basis, R&D capabilities, and strong professional manufacturers are more reliable. In general, small-scale manufacturers are not recommended. Not only is the technology immature, but it is likely that the company will close down after a few years. There will be a pile of scrap iron after the equipment is not repaired.

Third, the product of several key test points

The laser particle size analyzer has several key test points. (1) Laser selection: One of the important components of the laser particle size analyzer is HE-NE laser and semiconductor laser. The performance of HE-NE laser is better than that of semiconductor laser. And the cost is much higher than that of semiconductor lasers. The problem of poor unidirectionality of semiconductor lasers has a great influence on the stability of test results. Therefore, it is recommended that the user select the HE-NE laser.

(2) Photodetectors: The types of photodetectors used in domestic products are similar, and they are generally semi-circular, dot matrix, etc. The advantage of semi-ring type is that they can achieve high detection accuracy with fewer channels. And when a broken loop occurs, it can be temporarily taken together and manipulated, with little impact on the test results. The lattice type is an older detector type and it is now used less frequently.

(3) Instrument Structure Title: It is mainly divided into integral type and split type. The integral type is to integrate the decentralized system and the test system into one, and the collaborative operation. The split type is the decentralized system independent of the test system. The tester needs to manipulate the decentralized system first. , Disperse the sample and then guide the dispersed sample into the test system through the pipeline. This kind of shortcoming is that the cooperative manipulability is not good, the relatively heavy particles are easy to precipitate in the pipeline, the cleaning is inconvenient and has a certain impact on the test results. Now the equipment of the integral structure is the development direction, and the imported products mostly adopt the monolithic structure. Products are slowly developing toward monolithic structures.

(4) Optical path design: The optical path design is the basis for the development of the laser particle size analyzer. The advantages of imported products are not only in the manufacturing process, but also the design level of the optical path is a sign of advanced technology. Most domestic manufacturers now use simple parallel optical path design. It is known that the converged light Fourier transform light path is used in products introduced by Jinan Micron Corporation. This optical path is a more advanced optical path that can achieve wider scattering angles and has a certain advantage in improving test accuracy.

Fourth, need to understand the basics of particle testing

In actual tests, the correctness is relative, and the repeatability is correct: In the actual particle test, we cannot evaluate the “correct” or “incorrect” results of the laser particle size analyzer test because the samples are all irregular shape bodies. The test results that are compared with it are just another kind of instrument test results. Therefore, we can only say that the test results of the A instrument are correct relative to the B instrument. It cannot be said that the A instrument test result is correct or incorrect. The test staff always likes to compare with Malvern, as long as the match is correct, non-conformity is not correct, this is really a misunderstanding. The criterion for considering the quality of the equipment is really repetitive. Samples are sampled and tested separately. If the difference between the previous and subsequent test results is small, then the instrument is stable and repeatable. If the difference is large, it means the instrument. The test results are not good.

V. Field testing

It is advisable to send samples for field testing before selection. Because the properties of the samples vary widely, some instruments are not all-powerful and may have large deviations for some samples.