Industry news

Filter test principle

2020-10-17

※ The test principle of the bubble point method: When the filter membrane and filter element are completely infiltrated with a certain solution, and then pressurized on one side by the air source (our instrument has an air intake control system, which can stabilize the pressure and adjust the air intake), with When the pressure increases, the gas is released from the side of the filter membrane, indicating that bubbles of varying sizes and quantities appear on the side of the membrane. The corresponding pressure value determined by the instrument is the bubble point.

※ Diffusion flow test principle: Diffusion flow test means that when the gas pressure is at 80% of the bubble point value of the filter element, a large number of gas perforations have not yet occurred, but only a small amount of gas is dissolved into the liquid phase diaphragm first And then diffuse from the liquid phase to the gas phase on the other side, this part of the gas is called diffusion flow.

※ Why the method of diffusion flow is better: the bubble point value is only a qualitative value, from the beginning of the bubble to the last group of bubbles is a relatively long process and cannot be accurately quantified. The measured diffusion flow value is a quantitative value, which can not only accurately determine the integrity of the filter, but also reflect the problems of the membrane porosity, flow rate and effective filtration area, which is why foreign manufacturers use diffusion The reason for the integrity of the flow test.

※ Test principle of water intrusion method: The water intrusion method is dedicated to the testing of hydrophobic filter elements. The hydrophobic membrane resists water. The smaller the pore size, the greater the pressure required to squeeze water into the hydrophobic membrane. Therefore, under a certain pressure, the water flow squeezed into the filter membrane is measured to judge the pore size of the filter element.