Choosing the right filter bag can be confusing, especially when you’re dealing with critical processes like water treatment, chemical manufacturing, or food and beverage production. Micron ratings aren’t just technical jargon-they play a pivotal role in product quality, equipment protection, and process efficiency.
What Is a Micron Rating and Why Does It Matter?
A micron, or micrometre (μm), is one millionth of a metre (0.001 mm). In filtration, a filter bag’s micron rating refers to the average size of the pores or openings in its media. This rating indicates the minimum size of particle the bag is designed to capture. For instance, a 10-micron filter bag will capture the majority of particles that are 10 microns or larger, but smaller contaminants may pass through.
- Smaller micron values (e.g., 1, 5): Trap fine particles-essential for high clarity or purity.
- Larger micron values (e.g., 25, 50, 100): Allow more particles through-suitable for bulk or pre-filtration.
To help visualize: a human hair is roughly 70–100 microns thick, and fine sand grains are about 50 microns.
Nominal vs. Absolute: Decoding Filter Bag Ratings
All micron ratings are not equal. The two main types you’ll encounter in industrial filter bags are nominal and absolute ratings:
| Type | Efficiency | When to Use |
|---|---|---|
| Nominal | Removes 60–90% of particles at the rated size | General industry, water, preliminary filtration |
| Absolute | Removes >99.9% of particles at rated size | Critical uses: final food/beverage, pharmaceutical, high-spec chemical |
Most industrial and process fluid applications-including many handled with CLARIBag filter bags-use nominal ratings for a robust balance of performance and cost.
Micron Ratings in Water, Chemical, and Food Processes
Here’s how micron ratings are chosen-and what we recommend for specific sectors:
Water & Wastewater
- 1–5 micron: For fine/finish filtration (clarity, potable water, pure water).
- 10–50 micron: Sand, silt, sediment removal in process/cooling water.
- 50 micron & above: Bulk solids, debris, rust (pre-filtration, recirculation loops).
Chemicals, Oils, and Paints
- 1–10 micron: High clarity-inks, pigment, high-grade paints. Protects valves and pumps from fines.
- 10–100 micron: Process intermediates, slurries, and applications prioritising throughput over purity.
Food & Beverage
- 1 micron (absolute): Maximal clarity, microbial or haze removal before bottling-regulatory compliance.
- 5–10 micron: Removes visible particles; improves product appearance.
Real CLARIBag Filter Bag Applications
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CB-PPF11WN-FB (1 micron, Size 1): Polypropylene felt, ideal for highest clarity in food, beverage, or water circuits.
CB-PPF11WN-FB 1 Micron Filter Bag -
CB-PPF51WN-FB (5 micron, Size 1): Suited for sediment and fine particle removal in chemicals, oils, and industrial wash systems.
CB-PPF51WN-FB 5 Micron Filter Bag -
CB-PPF251WN-FB (25 micron, Size 1): Widely used for incoming water, paints, or extending finer filter life in general processing lines.
CB-PPF251WN-FB 25 Micron Filter Bag -
CB-PPF12WN-FB (1 micron, Size 2): For demanding, large-volume lines in food or beverage, where both clarity and flow rate are paramount.
CB-PPF12WN-FB 1 Micron, Size 2 Filter Bag
Step-by-Step: How to Select the Right Filter Bag
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Identify Required Particle Removal Size
- What’s the smallest particle you must remove? Microbial control requires 1 micron; removing bulk sand can be handled with 25–100 micron.
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Choose Nominal or Absolute Filtration
- Nominal: Most industrial, general food/water applications.
- Absolute: Regulatory, quality-critical end of line filtration.
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Select Filter Material
- Polypropylene: Excellent chemical resistance, suitable for food/water. Operating temperature up to 80°C-this is the CLARIBag standard for most bags.
- Nylon or polyester: For oil compatibility or higher temperatures.
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Size Bag for Process Needs
- Size 1 (7" x 16", 8 liter): Moderate flow/batch jobs.
- Size 2 (7" x 32", 17 liter): High-throughput, extended runs.
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Consider Total Cost of Operation
- Absolute-rated bags are more costly but reduce downtime for critical stages.
- Use nominal-rated bags for pre-filtration to extend life of finer bags or cartridges.
Optimising Your Filtration: Troubleshooting & Best Practices
- Monitor system pressure drop: A sharp rise means your filter is clogged and needs replacement. Use pressure gauge kits for precision tracking.
- For processes with metal particle risk, add magnet bars in your bag housing-especially when filtering wastewater or coolant streams.
- Regular review of captured solids can highlight upstream process issues or equipment wear.
Quick Reference Table: Filter Bag Micron Ratings and Typical Uses
| Micron Rating | Common Application | CLARIBag Example |
|---|---|---|
| 1 | Final stage filtration for food, beverage, high-clarity water | CB-PPF11WN-FB, CB-PPF12WN-FB |
| 5 | Ink, chemical, pigment removal; pump valve protection | CB-PPF51WN-FB |
| 10–25 | Coarse sediment, process water, bulk debris | CB-PPF101WN-FB, CB-PPF251WN-FB |
Key Takeaways
- Micron rating is crucial for matching bag performance to your process-be it microbial removal in bottling or bulk solids filtering in wastewater treatment.
- Nominal ratings suit most general industrial needs; absolute ratings should be reserved for quality-critical steps.
- Always consider chemical compatibility, temperature, and process volume before making your final selection.
If you’re struggling to match micron ratings, filter bag size, or material with your needs, our team at CLARIBag is here to help. Get in touch for tailored filtration advice or explore options in our current range-each product is engineered for exacting industrial requirements, including water, chemicals, oils, paints, food, and beverage.
