Filter bag systems are the workhorse of industrial filtration—found in water, wastewater, chemical, food, beverage, and engineering environments. But even the best filter bags can run into problems that undermine plant efficiency, threaten product quality, or result in costly downtime. From unexplained poor filtration, bag ruptures, to high pressure drops, these issues are real headaches for engineers and operators.
At CLARIBag, we've supported hundreds of facilities in troubleshooting and optimising their liquid filtration, drawing on deep technical experience in bag filter design, sizing, and industrial process support. In this blog, we share a detailed, insider's approach to isolating root causes, fixing problems, and getting your operations running reliably. Whether you're protecting pumps from abrasive particles, keeping chilled water clean for HVAC, or ensuring clarity in food & beverage production, the right troubleshooting makes all the difference.
Table of Contents
- Recognising Common Filter Bag Problems
- Poor Filtration Performance: Diagnosing & Solving Quality Issues
- Premature Filter Bag Failure: Causes & Corrective Actions
- Clogging and High Pressure Drop: Addressing Fouling & Blockage
- Physical Damage: Tears, Leaks, and Bypass Prevention
- Maintenance & Monitoring Strategies for Long Filter Life
- Quick Reference: Filter Bag Selection Tips
- When to Reach Out for Help
Recognising Common Filter Bag Problems
- Poor filtration or particle "breakthrough": Unwanted solids in the filtered product.
- Premature bag failure: Filter bags tearing, leaking, or wearing out far earlier than expected.
- Clogging/fouling: Rapid buildup of pressure drop across the filter, frequent bag changes.
- Physical damage/leaking: Tears at the seams, splits in the media, or leaks around the sealing collar.
- Bag bypass: Unfiltered liquid 'sneaks' past the filter bag instead of going through it.
Each of these symptoms is usually a clue about root cause, and targeted troubleshooting can address each in turn.
Poor Filtration Performance: Diagnosing & Solving Quality Issues
When solids appear downstream of the filter bag, the cause is usually either the wrong micron rating, media mismatch, or installation problems. Let's break these down:
1. Incorrect Micron Rating
- If particle retention is insufficient (solids visible in "filtered" liquid), the selected filter bag is likely too coarse.
- Common industrial applications—like the removal of silt (20–50μm), sand (100μm), or yeast (3–40μm)—require micron ratings specifically tailored to those targets.
- For water and wastewater, general protection often starts at 50–100μm (polypropylene felt or nylon mesh), moving down as needed to 10–25μm or even 1μm in polish stages. For food & beverage (e.g., honey, kombucha), ratings of 100–200μm are frequently chosen for clarity and yield.
Solution: Assess your process requirements, review micron rating charts (like those in our application guides), and step down in stages if unsure. For in-depth sizing assistance, consult our specialists or use our Filter Bag Selector Tool.
2. Media Selection Mismatch
- Polypropylene felt excels in water/chemical compatibility but may fail with aromatic hydrocarbons.
- Nylon monofilament mesh is robust for food & beverage, but vulnerable to concentrated acids.
- Polyester felt has maximum temperature for industrial wastewater and high-temp food applications (up to 120°C).
Solution: Always reference the material compatibility charts. Upgrade to a bag rated for your operating conditions.
3. Faulty Bag Seating or Bypass
- Improper collar fit allows liquid to flow around the collar, not through, the filter.
Solution: Improve installation procedures and train operators to check that bag collar fits correctly.
Premature Filter Bag Failure: Causes & Corrective Actions
Too-frequent filter bag changes or visible bag rupture can be costly and disruptive. Let's consider key failure modes.
1. Mechanical Damage (Tears, Abrasion, Burst)
- Sharp/abrasive particles like metal shavings can erode or cut the media.
- Rapid bag pressurisation during filter start may cause seams to give way
Solution: Monitor pressure drop. For size 1 & 2 bags, max differential pressure is usually 1 bar (15 psi) at 20°C. If you routinely see pressure drop reaching 1 bar quickly, add upstream coarse filtration or reduce flow per bag. During filter restart, open the filter inlet valves slowly and gradually increase the flow rate. If the rupture is caused by abrasives, discuss options with our technical team.
2. Chemical or Thermal Attack
- Exposure to aggressive acids, alkalis, or solvents outside the recommended range will cause rapid degradation.
- Operating above maximum temperature limits (Polypropylene 80°C, Polyester/Nylon 120°C) and weakens media.
Solution: Always select bags according to the full chemical and temperature profile. If in doubt, consult our compatibility charts or technical team.
3. Frequent Wetting/Drying Cycles or Air Pockets
- Air trapped in bag housings can cause poor wetting of felt media, leading to uneven loading and premature failure.
- Poor venting or rapid temperature swings can shorten bag life.
Solution: Install automatic air vents. See our Bag Filter Accessories for pressure gauge and vent kits.
Clogging and High Pressure Drop: Addressing Fouling & Blockage
Is your filter bag needing changeout long before it should—or do you see sudden spikes in differential pressure?
- High suspended solids, insufficient prefiltering, or very fine bags for coarse feed cause fast blinding.
- Organic sludge, biofilm, scaling, and gelatinous contaminants (especially in wastewater/food processes) will clog the surface and depth media quickly.
Solutions:
- Use staged filtration: Start with a coarse mesh bag (1000 micron, Size 1 Nylon mesh) and step down to finer felts (e.g., 25μm, 10μm) as needed.
- Clean or backflush upstream equipment periodically.
- For stubborn fouling, consider using multi-bag housings or increasing surface area, especially if solid loading is high.
- Replace bags at or just before 1 bar pressure drop for longest service life.
Physical Damage: Tears, Leaks, and Bypass Prevention
- Fit and seat filter bags carefully. The most common installation issue is an incorrectly placed collar—especially at the lid hinge in horizontal bag housings. Be sure to ease the bag into the seat and close the lid gently.
- If repeated leaks or tears occur, check for sharp edges or burrs on the housing seat.
Maintenance & Monitoring Strategies for Long Filter Life
- Install differential pressure gauges and record readings at each bag change.
- Use only compatible replacement bags. Keep a small inventory in stock to avoid emergency substitutions.
- Inspect used bags for "patterns" to inform improvement: Is the bag loaded evenly? Are failures always in the same place?
- Replace housing O-rings and seals as part of planned maintenance.
- Train staff to detect common failure modes
Quick Reference: Filter Bag Selection Tips
- Water, wastewater, HVAC circuits: Polypropylene felt, 10–100μm typical (50μm, Size 2 Polypropylene felt works well)
- Chemicals: Match material to chemistry, favouring Polypropylene or Polyester depending on acid/base/solvent content.
- Food & beverage: Nylon monofilament mesh at 100–200μm for straining/clarity, Polypropylene felt for finer filtration.
- Paints, coatings, viscous liquids: Use mesh in the 200–600μm range for initial removal, stepped down to 50μm as needed.
Download our detailed application and sizing charts from the Technical Information & Downloads page, or use our Filter Bag Finder Tool.
When to Reach Out for Help
Persistent issues—such as recurring bag failures, unexplained quality problems, or troubleshooting complex process chemistry—call for a tailored solution. Our team at CLARIBag can help with sample testing, product selection, and even custom manufacturing for unique or legacy systems. Engineers, technicians, and plant managers around the UK and beyond trust us with their filtration problems, large and small.
Want to discuss your specific challenge? Contact our technical team today or browse our extensive range of industrial filter bags for reliable, proven filtration performance.
