What is the difference between the rated pore size and absolute pore size of microporous filtration

When selecting microporous filtration membranes, the terms "rated pore size" and "absolute pore size" are often used. So, what are their general meanings and differences?

The "rated pore size" of a microporous filtration membrane refers to the nominal or average pore size specified by the manufacturer for a given microporous membrane. It is also the design and manufacturing size of the membrane pore size. It represents the pore size range of the membrane for effective filtration. The rated pore size is usually Determine using standardized methods or industry guidelines, such as those developed by the American Society for Testing and Materials (ASTM) (ASTM F316-03) for determining the bubble point and mean flow pore size of membranes; the international standard "Particle Size Analysis - Laser Diffraction Method" ” (ISO 13320), using laser diffraction technology to measure particle size distribution; Japanese Industrial Standard (JIS K 1474) method for determining the maximum pore size and bubble point of microporous filters, etc.

The "absolute pore size" of a microporous filtration membrane refers to the actual size of the smallest pore in the membrane, which represents the largest size of particles that can pass through the membrane. The absolute pore size is usually determined experimentally using techniques such as bubble point testing, microscopic analysis, or particle challenge testing. Absolute pore size Pore size provides a more accurate measure of a membrane's filtration performance.

The main differences between nominal bore diameter and absolute bore diameter are as follows:

1. Definition, the nominal pore size is the specified nominal or average pore size provided by the manufacturer, which reflects the pore size range of a physical opening, while the absolute pore size refers to the actual physical size of the smallest pore size in the membrane.

2. Measurement method, nominal aperture is usually determined according to standardized methods or industry guidelines, while absolute aperture is determined by experimental testing that directly measures the minimum aperture.

3. Filtration performance. The rated pore size can indicate the expected filtration performance of the membrane, while the absolute pore size can more accurately measure the actual filtration capacity of the membrane.

4. Variability. Nominal pore size is usually specified within a range, acknowledging that there may be some variability in pore size across the membrane, whereas absolute pore size refers to the minimum pore size of a microporous membrane and does not account for potential variation.

As a user, you can use the rated pore size to select a suitable microporous filtration membrane, and select the range of the rated pore size of the membrane according to the size range of the filtered object. The absolute pore size can more accurately control the filtration of the membrane in the application. Performance, of course, absolute pore size is also an important reference condition for membrane selection. For example, when selecting a membrane for bacterial filtration, it is necessary to comprehensively consider the rated pore size and absolute pore size from many aspects, the size range of particles that need to be filtered, and the minimum possible The size of filter particles, etc., to ensure the effectiveness and reliability of filtration.