Eight advantages of the most popular static capaci

2022-08-11
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Compared with the dynamic method (continuous flow chromatography), the static volumetric method has the following eight advantages over the surface and porosity analyzer:

1. The pressure of nitrogen is directly measured by the pressure sensor, excluding the influence of other factors, The dynamic method can only be obtained by nitrogen and the value displayed by the computer: it is the average value of the experimental group, the change of the relative amount of helium and the adjustment of the flow rate of both

2. the adsorption and desorption process of the sample is carried out under static state and reaches the adsorption equilibrium, which conforms to the ideal adsorption equilibrium conditions, while the dynamic method is only a relative dynamic equilibrium

3. In the process of adsorption and desorption, the sample is fixed in the liquid nitrogen dewar bottle. Unlike the dynamic method, the sample tube needs to enter and exit the liquid nitrogen Cup once for every pressure point measured. The static method not only saves time, but also greatly reduces the consumption of liquid nitrogen

4. only nitrogen, no helium, and the consumption of nitrogen is very small, which greatly reduces the cost of testing

5. Each pressure point measured by the static volumetric method only takes about 2 minutes, and many points can be measured as needed. For example, the multi-point BET specific surface can be measured at more than 6~20 points, and the pore size distribution can be measured at 25~100 points. The number of measured points is more conducive to the improvement of measurement accuracy and reliability. In contrast, the dynamic multi-point BET specific surface can only be measured at about 5 points, and the pore size distribution can only be measured at about 10 points, Moreover, under the condition of measuring the same number of points, the static method saves more time

6. in the aperture distribution test, the static volumetric method has more significant advantages. First, the dynamic method is limited by the sensitivity of the thermal conductivity detector and the accuracy of flow regulation, and the aperture test range is small, generally 2~100nm, while the static volumetric method can reach 1~300nm; Second, the dynamic method can not test the complete isothermal curve, and the number of points measured to promote the healthy and orderly development of the polyurethane insulation industry is small, and the analysis of pore size distribution is relatively rough, while the static capacity method can completely test the isothermal adsorption curve. When purchasing the chromatogram, it will think of the isothermal desorption curve, so as to achieve a more accurate analysis of pore size distribution, and obtain the complete adsorption characteristics of the sample, Then the adsorption type and pore structure of the sample can be judged

7. The instrument of static capacity method can realize real full-automatic control, including no need for midway press (including punch and hydraulic press). It is a general-purpose press with exquisite structure, which artificially replenishes liquid nitrogen, and its operation, control, data acquisition and processing, and computer operation are more simple, smooth, reliable and intelligent. As long as the test conditions are input into the computer, the test process will be completed automatically, Get all test results synchronously

8. the pretreatment of samples can be carried out in the same machine or even in the same position. Using the vacuum condition of the host and a separate temperature control device, the pretreatment is more sufficient, the operation is simpler, and the test results are more reliable

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