Choose the appropriate liquid filter bag method

- Jan 23, 2020-

Choose the appropriate liquid filter bag method


First, we need to understand the filtration mechanism of the bag filter system: the liquid flows from inside the bag to outside the bag, and the particles are trapped inside the bag. The bag filter works by pressure filtration. The bag filter system mainly consists of three parts: filter container, support basket and filter bag. Today we're going to look at the filter bags.


1. Material selection of liquid filter bag:


First according to the chemical name to filter the fluid, according to the filter material of chemistry with taboo to find available, then aiming at the filter medium temperature, operating pressure, ph, viscosity (CPS), types of impurities such as (hard particles, soft particles), impurity content (PPM), operating conditions (such as whether to need to tolerate steam, hot water or chemical sterilization, etc.), assessed, and shall not apply to the filter material. Use is also an important consideration. Filters for drugs, food or cosmetics, for example, must be fda-approved; For ultrapure water, filter materials that are pure and do not contain release materials that affect specific impedance should be selected. Filter gas must be selected hydrophobic material and whether the need for "sanitary filtration" design, and so on.


2. Selection of filter bag precision:


This is one of the most vexing questions. For example, to remove visible particles, use a 20 - or 25-micron filter bag. To remove the cloud in the liquid, use 1 - or 5-micron filter bags. To remove the smallest bacteria, a 0.2 micron filter bag is required. The problem is that there are two units of filtering accuracy: absolute/nominal.


Absolute precision means that the particle can be filtered with 100% of the indicated accuracy. Is an impossible and impractical standard, because 100% is an infinite value. The general term on the market for absolute filters such as thin films, strictly speaking, can only be said to approach the absolute filter


There is no standard of nominal precision that industry can agree upon and follow. That is to say, 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 filter may be as accurate as company b's 5-micron filter, or finer. Experienced professional filter suppliers can help with the selection of filter accuracy, and the fundamental solution is "trial".

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