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How to select material for liquid filter bag?

January 11,2022

The filtrate filtration surface of the liquid filter bag is subject to special singeing treatment, which not only effectively prevents the fiber from polluting the filtrate, but also avoids the excessive blockage of the filter hole caused by the traditional rolling treatment and shortens the service life of the filter bag. All raw materials are white without any special bleaching and dyeing treatment, which fully meets the environmental protection [1] standard. Moreover, due to the three-dimensional filter layer of needle felt, when the liquid flows through the filter bag, the particles will stay on the inner wall surface and deep layer of the liquid filter bag due to the deep filtration mechanism, which has high capture efficiency for solid or colloidal particles. The uniform thickness, stable opening rate and sufficient strength of the needle felt make the efficiency of the filter bag stable and the application time longer. Five thread double needle sewing ensures the best filtration guarantee for each liquid filter bag. It has a wide range of applications and is suitable for liquid filtration in various industries.


Ring mouth material

Material: polypropylene (PP), polyester (PE) ring mouth: stainless steel, galvanized, nylon, PP, PE

Process: sewing and hot melt welding accuracy: 1.0 ~ 300um

Size: 1#( φ 180*420mm) 2#( φ 180*810mm)

3# ( φ 105*230mm) 4#( φ 105*380mm)

5# (φ 150 * 520mm) Y Series( φ 202 * 330mm) and other non-standard dimensions


Liquid filter bags are generally made of the following materials:

  1. Nylon filter bag – material: NMO nylon monofilament
  2. Polypropylene filter bag – material: Polypropylene needle felt or melt blown polypropylene
  3. Polyester PE filter bag – material: Polyester needle felt
  4. PTFE filter bag – material: Teflon needle felt
  5. Stainless steel filter – stainless steel 304 or stainless steel 316

In addition, there are polypropylene multi-filament, polyester multi-filament, aramid needle felt, etc.


Product application

It is suitable for filtering general industrial liquids, such as electroplating e, D paint, ink, coating, food and other chemical solutions; Acid and alkali resistant fiber has high mechanical strength and can be used repeatedly.


Selection of filter bag material:

Firstly, find out the available filter materials according to the chemical name of the fluid to be filtered and the chemical cooperation taboo, and then evaluate them one by one according to the filter medium temperature, operating pressure, pH value, viscosity (CPS), impurity type (hard particles, soft particles), impurity content (PPM), and operating conditions (e.g. whether it is necessary to withstand steam, hot water or chemical sterilization, etc.), And remove unsuitable filter materials. Use is also an important consideration. For example, the filter material for drugs, food or cosmetics must be FDA approved; For ultrapure water, the filter material that is pure and does not contain the release that will affect the specific impedance shall be selected; For gas filtration, hydrophobic materials must be selected and whether “sanitary filtration” design is required, etc.


Accuracy selection of filter bag:

This is the most troubling problem. For example, to remove particles visible to the naked eye, a 20 or 25 micron filter bag should be selected; to remove the cloud in the liquid, select 1 or 5 micron filter bag; to filter out the smallest bacteria, a 0.2 micron filter bag is required. The problem is that there are two units of filtering accuracy: absolute accuracy / nominal accuracy


Absolute accuracy refers to 100% filtration of particles with marked accuracy. It is almost an impossible and impractical standard, because 100% is an infinite value. Generally known as absolute filters on the market, such as thin films, strictly speaking, they can only be called “approaching absolute” filters


Nominal accuracy does not have a common standard recognized and followed by operators “In other words, company a can set the nominal accuracy at 85-95%, while company B would rather set it at 50-70%. In other words, company a’s 25 micron filtration accuracy may be equal to company B’s 5 microns or finer. For this problem, experienced professional filter suppliers will help to select the filtration accuracy, and the fundamental solution is” trial “.


The working conditions and effects of each material are different. How to select the correct material for the liquid filter bag requires your process engineer to provide the following parameters:


  1. What liquid is filtered? Is the liquid acid-base and solvent composition?
  2. What types of impurities are removed? Soft impurities or hard particles?
  3. What is the filtering effect? That is, the filtration accuracy and the filtration efficiency of the filter bag
  4. What is the filtration temperature?
  5. Are there requirements for filtration flow and initial differential pressure of filtration system?


According to the above complete parameters, the most suitable filter bag can be accurately selected. If we can’t know such specific filtration process parameters at present, we have accumulated rich filtration application experience in various industries, can give the best recommended filtration scheme according to your general requirements, and can provide the tested system for testing, and finally design the most suitable overall filtration scheme.

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