Product description
Absolute rated filter bags for precise liquid filtration
Absolute Rated Filter Bags are designed for liquid filtration applications where consistent and highly reliable particle retention is required. Unlike nominal filter bags, absolute rated filter bags provide a clearly defined filtration efficiency, making them suitable for critical processes where filtration performance must be predictable and repeatable.
These filter bags are commonly used in applications where product quality, downstream protection or regulatory requirements demand a high level of filtration control.
What does absolute rated filtration mean
Absolute rated filtration refers to a filtration efficiency that is defined at a specific particle size, typically expressed as approximately 98 percent retention at the stated micron rating. This means that particles equal to or larger than the rated size are consistently removed at a very high efficiency level.
This differs from nominal filtration, where particle retention is approximate and can vary depending on operating conditions.
Filtration principle
Absolute Rated Filter Bags use depth filtration based on advanced microfiber media with a graded pore structure. Liquid passes through progressively finer pores, allowing particles to be captured throughout the depth of the filter rather than only on the surface.
This filtration principle provides:
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precise and repeatable particle retention
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consistent filtration quality over time
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stable pressure drop behaviour
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reduced risk of particle breakthrough
Depth filtration also allows higher dirt holding capacity compared to surface filtration methods.
Seamless and low bypass design
Many absolute rated filter bags are manufactured using seamless or thermally bonded construction techniques. This eliminates needle holes and weak points that can cause unfiltered bypass in sewn filter bags.
Key design benefits include:
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reduced bypass risk
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improved resistance to channeling
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stable performance under fluctuating flow or pressure
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consistent filtration results
Design and construction
Absolute Rated Filter Bags are typically manufactured from polypropylene microfiber materials selected for filtration efficiency and chemical compatibility. The media is designed to retain particles across a wide size distribution while maintaining mechanical strength.
Typical construction features include:
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graded pore microfiber depth media
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thermally bonded or seamless structure
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integrated sealing ring to prevent bypass
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high tensile strength for industrial operation
The materials used are free from sizing agents, bonding adhesives, resins and silicones.
Performance characteristics
Absolute Rated Filter Bags offer:
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clearly defined micron ratings
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high and consistent filtration efficiency
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predictable pressure drop behaviour
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extended service life compared to nominal filter bags
These characteristics make them suitable for both continuous and batch filtration processes where reliability is critical.
Material compatibility and hygiene
The polypropylene construction provides compatibility with a wide range of industrial liquids. Absolute rated filter bags are suitable for applications where product cleanliness is important and where contamination control is required.
Selected variants can be used in food, beverage, water and chemical processing applications, depending on certification and configuration.
Typical applications
Absolute Rated Filter Bags are commonly used in:
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high purity water filtration
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food and beverage processing
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pharmaceutical and biotechnology processes
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chemical and specialty chemical filtration
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coatings, paints and resins
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polishing and final filtration stages
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protection of downstream membrane or cartridge filters
Key benefits
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Absolute rated filtration for predictable performance
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High efficiency particle retention
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Depth filtration with high dirt holding capacity
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Reduced bypass compared to nominal filter bags
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Stable pressure drop behaviour
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Suitable for critical and high purity applications
Selection and configuration
Absolute Rated Filter Bags are selected based on:
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required micron rating
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bag size
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process liquid characteristics
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operating pressure and temperature
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required filtration efficiency
Filtra International can support correct selection to ensure optimal performance and service life.