8 Parameters for You to Better Understand Filter Membrane

Today, HAWACH also discusses the parameters for you to have a better understanding of the filter membrane.

Parameters of the filter membrane
1. Aperture
There are different apertures available for HAWACH filter membranes, 0.1um, 0.22um, 0.45um, 0.8um, 1.0um, 3.0um, 5.0um, 10.0um. But it should be noted that not all membranes or roll membranes have so many pores.

2. Size
The round membrane is represented by diameter. Different diameters are available, 293mm, 142mm, 90mm, 47mm, 25mm, and 13mm. It should also be noted that not all filter membranes of all materials have each diameter above, and the specifics can be confirmed by consulting HAWACH team. The rolling membrane is a rectangular roll together, expressed by the width. The widths are: 254, 260; 270; 280; 310mm and the inner core is 22mm.

3. Bubble point
For the use of a specific liquid wet filter membrane at a specific temperature, it is the minimum pressure of the liquid that must be squeezed out of the filter membrane pores, in the microporous membrane industry. According to standard, the 0.22μm is ≥0.31mpa; 0.45μm ≥0.17mpa.

4. Flow rate and flux
The pore size is proportional to the flow rate, the larger the pore size, the faster the flow rate. Flow rate and flux are two important parameters of filter material and design performance, which depends on these aspects:

Viscosity: Viscosity determines the ease of liquid flow. The viscosity of the liquid is inversely proportional to the flow rate.

Pressure difference: it means the filter inlet and outlet pressure difference. It increases when the filter is fully loaded.

Porosity: It is the ratio of all the pores volume in the membrane to the membrane volume. It’s commonly used 50%-90% pore area membranes, which is directly related to the flow rate.

5. Filter material life
It refers to the maximum lifetime of a filter under specific operating conditions. It depends on many factors, such as the nature of the filtrate, the operating temperature, the choice of filter material, etc.

6. Filter efficiency: The filtering efficiency is defined by the amount of filtration and the blocking particle size at their specific pressure. The lower pressure, the greater filter’s effectiveness.

7. Hydrophilic and hydrophobic
Hydrophilicity is defined as hydrophilic. Hydrophilic membrane filter usually has a special chemical layer to make the membranes infiltrated by water; Hydrophobicity is a reference to the repulsion of water. Hydrophobic membranes rarely absorb water at all. It can be observed that small water droplets stay on the surface of the filter membrane and will not be absorbed by the surface and diffused into the water surface.

For instance, the nylon membrane is suitable for the filtration of water and organic solvents, such as sample preparation for high performance liquid phase and gas chromatography. It is characterized by large flux, low dissolution, and mechanical strength. Nylon’s good physical properties can meet the demanding analysis requirements of various test conditions.

The size of the hydrophobicity depends on the pore size of the filter and the characteristics of the filter membrane material. For the hydrophobic membrane, it does not absorb moisture, is easy to be constant weight, can be repeatedly autoclaved, and has the same performance, thin texture, fast flow rate, chemical resistance, oxidation resistance, and becomes a hydrophilic membrane after alcohol treatment. It can be applied to purification of suspended particles in the air and sterilization of air in the fermentation industry; purification of insoluble oils and weight analysis of solid particles; separation and purification of non-specific proteins; concentration of aqueous solutions, separation, and recovery of chemical substances.

8. Pack
For different membranes, the number in each box is different. For example, 47mm is 100pcs/pack, and 142mm is 50pcs/pack.