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Filter Bag use and selection
2013-07-11 10:33:00

Filter Bag use and selection
The selection of the filter material:
First, in accordance with the fluid to be filtered chemical name to identify the availability of the filtering medium by chemical complexes contraindications for its operating temperature, operating pressure, pH, operating conditions (e.g., whether it is necessary to withstand steam, hot water or chemical sterilizing , etc.), assesses on a case-by-case basis, and remove the filter does not apply. Use is also an important consideration, for example, pharmaceuticals, food, or cosmetic use of filter must be permitted by the FDA material; ultrapure water shall be a pure selection will affect the filtering medium of the filtrate does not contain emissions; and the need for Health stage filter design, and so on.
Bag filter accuracy:
This is one of the most vexing problems. For example, to remove particles visible to the naked eye, you should use a 25-micron filter; 1 or 5 micron filter to remove the liquid cloud-like, to use; smallest bacteria you need a 0.2 micron filter to filter out. The problem is that there are two types of filtration precision units: absolute accuracy / precision of nominal.
Absolute precision / accuracy of the nominal
The absolute accuracy of the particle filter can be 100% accuracy marked. Any kind of filter, it is almost impossible to achieve, and not the de facto standard, because 100% is an infinite value. Absolute filters commonly known in the market such as film or the like, strictly speaking, can only be called "is approaching absolute" filter, while others are the nominal accuracy, the precision of the nominal, This is mainly troubled where: nominal accuracy and Without a common identify and comply with the standard. That A nominal accuracy is set at 85-95%, while Company B would rather be set at 50-70%. In other words, a 25 micron filtration precision may be equal to Company B 5 microns or finer. This issue, experienced professional filter supplier can help the most suitable filter, the fundamental solution "trial". In accordance with the the filtration temperature when the viscosity:
Professional filtration equipment suppliers can estimate how much the filter bag can bear, how much the flow rate and the forecast of primary pressure drop. If we can provide the content of impurities in the fluid, and can even be estimated life.
Acid bag use.
View installation the bag Specification and filter interface is consistent and check the quality of the new bag for defects.
Bag along with the support network, and close to the inner wall of the support network, pay attention to check the inner wall of the support network Blue no glitches.
When the filter downstream pressure difference at 1-1.5Kg/cm2 please replace it with a new bag or cleaning bag.
4. Narrow polypropylene, nylon or polyester filter bag is usually made of these materials less hydrophilic, the surface of the fiber will not be wetted with water before use, must use some other surface lower tension of the liquid to wet it before installation, you must bag immersed in the filtered liquid pre-wet for a few minutes, the fiber is wet, the liquid due to capillary action and suction filter This can effectively reduce the initial pressure loss.
Bag filter material properties are as follows:
Polyester - the most commonly used filter fiber, good chemical resistance, operating temperature less than 150 ° C.
Polypropylene - liquid filtration for the chemical industry, excellent acid, alkali function, operating temperature less than 100 ° C.
Wool - good anti-solvent, but not for acid-fast, alkali filter
Nylon - good chemical resistance function (except acid), operating temperature less than 170 ° C.
Fluoride - with the best resistance to temperature and chemical resistance, operating temperature is less than 250-270 ° C.
Select the correct filter system First should understand the medium was filtered maximum flow, viscosity, an impurity content, as well as operating pressure, temperature, impurity particles size distribution, the nature of the chemical medium, pipe type and size, and then select the appropriate filter and filter bags. With specific reference to the following table, and then select the matching bag (SPC bag filter products directory) select a filter.
Filter bag features:
Surface filter - nylon monofilament braid directly trapped particles, precise aperture, can be washed repeatedly, for retention of large diameter particles, representative material for nylon monofilament.
Depth filtration - non-woven inner layer of the three-dimensional space, direct interception adsorption of fine particles, with high efficiency, low cost, large capacity dirt features. Generally does not recommend the reply. More suitable for high viscosity liquids or small diameter particles trapped efficient, representative material for polyester and polypropylene.
Acid filter bag filter mechanism:
The liquid from the filter bag to the outer bag, the filtered particles are trapped in the bag, so that the working principle of the bag filter is a pressure filter. The entire bag filter system consists of three parts: the filter container, the support basket and filter bags.
To filter the liquid injected from the top of the filter bag is supported by the support basket, which allows uniform distribution of the liquid in the entire surface of the filter bags, and without the negative effects of turbulence.
Liquid from the filter bag to the bag, filter out particles are trapped in the bag, making the replacement filter bags without polluting the filtered liquid. Filter bag handle design allows quick and easy replacement of the filter bags.