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A فلتر كيس is a type of filter that uses filter bags as the filter element. It has a simple structure, relatively low cost, and is a widely used filter system.
1) Filter housing. The housing is a sealed space that withstands system pressure. It provides space for the working fluid and filter bags and guides the flow of the fluid.
2) Filter bag support basket. The support basket is usually a perforated mesh cylinder with a large opening ratio. It is used to support the filter bags and prevent them from deforming or being damaged under fluid pressure.
3) Filter bag. The filter bag is the core component of the filter. It traps solids in the liquid within its casing while allowing the liquid to pass through, achieving continuous filtration.
How do bag filters work?
Bag filters typically employ an inlet-outlet filtration direction. When liquid enters the housing through the filter inlet, it slowly fills the inside of the filter bag. The fabric structure of the filter bag traps solids larger than the required filtration precision on its surface, while the clean liquid passes through the filter bag and flows downstream through the filter outlet.
When solid contaminants accumulate in the filter bag and the internal pressure rises to a certain limit, filtration can be stopped to replace the filter bag. A dual-unit structure (one standby, online switching) can reduce downtime and facilitate replacement and maintenance operations.
Common standard filter bag sizes:
Filter bag model | Diameter mm | Length mm | Recommended flow rate m3/h | Filtration area (m2) |
#1 | 180 | 450 | 20 | 0.25 |
#2 | 180 | 810 | 40 | 0.5 |
#3 | 108 | 230 | 60 | 0.09 |
#4 | 108 | 380 | 12 | 0.16 |
Based on the different filter media, filter bags can be divided into:
1. Non-woven fabric (filter felt) filter bags. Common materials include PE polyester, PP polypropylene, and PTFE polytetrafluoroethylene. Filtration accuracy ranges from 1 micron to 100 microns.
2. Monofilament woven mesh filter bags. Common materials include PE polyester, PP polypropylene, and Nylon monofilament. Monofilament woven mesh can be repeatedly washed and is often used for low-precision coarse filtration. Filtration accuracy ranges from 50 to 1000 microns.
3. Metal wire mesh filter bags. Typically use 316L metal woven mesh. Can be repeatedly washed and is heat-resistant. Filtration accuracy ranges from 50 to 1000 microns.
Based on their structural form, bag filters mainly include the following types:
1. Single Bag Filter. Standardized filtration equipment that can be quickly deployed into a filtration system. Customization of inlet and outlet locations and sizes is also available to meet individual needs.
2. Multi-bag filters. Multi-bag filters are suitable for high-flow-rate applications and are typically configured with 2 to 24 bags. Customization is also available for more filter bags.
3. PP/PVDF plastic bag filters. Compared to traditional stainless steel bag filters, PP/PVDF plastic bag filters can withstand higher concentrations of acid and alkali solutions, making them more suitable for harsh filtration environments.
