Filter material through hole aperture test method comparison - Database & Sql Blog Articles

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Kaixin micro test

Test probe P100-M3

There are various methods for testing the pore size of the material, such as nitrogen adsorption, mercury intrusion, and bubble pressure. However, the most suitable method for testing the pore size of the membrane is to use a bubble pressure method (gas-liquid flooding method) for testing. The reasons are as follows:

First, the shortcomings of nitrogen adsorption

1. Aperture range: 0.35-500 nm, which cannot be tested for micron-sized holes.

2. The nitrogen adsorption of the diaphragm also has a large error. The reason is that the inner and outer surfaces of the diaphragm are smooth, smaller than the surface, and the adsorption amount is small, so the error is large.

3. The diameter of the hole in the diaphragm material (ie the diameter at the narrowest point of the through hole) is the most critical and most important, while the nitrogen adsorption test is the through hole and blind hole of the material, so the aperture test error will be very large. .

Second, the disadvantages of mercury intrusion

1. Aperture range: 50nm-500um; if you want to test a small pore size, such as 100nm or less, you need a very large pressure (20MPa or more) to inject mercury into the material channel, so that the large pressure is under normal pressure, under high pressure. The pore structure of the membrane material may be deformed or even crushed, causing the result to deviate from the theoretical value; however, for the bubble pressure method, the pressure applied to the material is much smaller, generally below 0.1 MPa.

2. Like the nitrogen adsorption, the mercury intrusion method tests the through holes and blind holes instead of the diameter at the throat.

Third, bubble pressure method

1, the test aperture range is 10nm-500um;

2. The diameter (minimum pore size), maximum pore size, average pore diameter, pore size distribution and permeability of the pore throat of the through hole are tested;

3, the test principle is suitable for testing the pore size of the membrane material
3H-2000PB bubble pressure filter membrane pore size analyzer

The basic principle is gas-liquid drainage technology (bubble pressure method): applying a pressure difference to both sides of the membrane, overcoming the surface tension of the immersion liquid in the membrane pores, driving the immersion liquid through the pores, thereby obtaining a through-hole of the membrane-like material. The pore size data of the throat, and this method is also the standard method for ASTM film determination.