Seal selection in bag filter housings: Ensure leak free performance

In this guide, we share our expertise in choosing, installing, and maintaining lid seals in bag filter housings, giving you the confidence to keep your operations leak-free, safe, and efficient.

Why Lid Seals Are Crucial in Industrial Bag Filter Housings

• Health & Safety Hazard: Incorrect material selection and damaged seals can allow the liquid to leak from housing lid and create a hazard, especially in high temperature and chemical applications
• Protecting Equipment: Proper sealing prevents air ingress, which can cavitate pumps or cause erratic flow controls. In chemical and food plants, a failed lid seal could allow contaminants into critical process streams.
• Maintaining Differential Pressure: Filter housings rely on sealed systems to provide a reliable pressure drop figure

How to Select the Right Lid Seal for Your Bag Filter Housing

• Material Compatibility
  
  • Viton: Robust for aggressive chemicals, hot applications, and when broad compatibility is crucial. For example, our BFOS Housing Lid Seal 5179510502 (Viton type) is used in both Size 1 and Size 2 stainless steel filter housings and handles a wide variety of chemical and high temperature liquids. This is our standard seal for industrial bag filter housing range. 
  • EPDM: Generally preferred for water and mild chemicals, including some food and beverage processes. It handles most cleaning solutions and steam up to moderate temperatures.
  • Buna-N (Nitrile): Effective for water but limited chemical and heat resistance—less common in food or aggressive chemical duties.
  • PTFE-encapsulated: Essential for highly corrosive duties where standard rubber-based seals fail.
• Correct Profile and Dimension: Matching the precise profile (O-ring cross-section, diameter, or custom gasket shape) and dimension to your housing is fundamental. An oversized or undersized lid seal will inevitably create paths for bypass or leakage, so always reference the housing model and bag size when ordering.
• Operating Conditions: Know your maximum system temperature, pressure, and the chemical composition of liquids processed. For example, our stainless housings for Size 1 and Size 2 bags are rated to 10 bar and up to 80–90°C, so the seal must equally withstand those conditions.
• Compliance and Certification: For food, beverage, or pharmaceutical use, seals must be made from food-contact approved compounds (for example, FDA-grade Silicone or PTFE encapsulated) and supplied contamination-free. Always check the certifications relevant to your application.

When to Choose Each Lid Seal Material

• Viton (FKM): Best for chemical and oil processing, suitable up to 200°C, compatible with aggressive solvents and acids. Used in applications like paint, coatings, and higher-end chemical filtration.
• EPDM: Resistant to hot water and most common cleaning chemicals. Widely used in water treatment lines.
• PTFE or Encapsulated Seals: For the harshest chemical environments or when working with unknown liquid mixes. Not typical in everyday water or mild process applications, but indispensable in specialised industrial lines. Also common in food and pharmaceutical applications. 
• Silicone: FDA approved Silicone is the material of choice for non aggressive food or pharmaceutical applications. 

Correct Sizing: Ensuring a Leak-Free Fit

One of the most common causes of leaks is using a seal that is not the correct fit for your housing. Check both:

• Housing Model Compatibility: For example, the BFOS2-10/F80-A2 uses seals specifically designed for Size 2 (7" x 32") bags. Using seals from another housing size can mean gaps at the closure or distorted O-rings, immediately compromising seal integrity.
• Seal Cross-Section/Profile: Even among correct diameters, different models may use round O-rings or flat gaskets. Always specify precisely or source directly by housing serial/model number.

Installation Best Practices: Achieving Leak-Free Performance

• Cleanliness is Key: Always start with a completely clean groove and lid. Any residue, grit, or remnants of a previous seal can prevent full seating and cause leaks.
• Lubrication: Apply a compatible lubricant (food-grade if necessary) to the seal before installation. This helps prevent O-ring twists, pinching, or extrusion during lid closure. Do not use petroleum-based lubricants on EPDM or food applications.
• Uniform Tightening: For bolted housings, tighten bolts in a crosswise or star pattern. Over-tightening one side can skew the lid and cause uneven compression, leading to premature O-ring damage and bypasses.
• Initial Pressure Test: After assembly, gently ramp up pressure and perform a visual check for drips or seepage at the lid. If minor leaks are observed, gently retighten all bolts in sequence but avoid over-torquing, which can permanently deform seals.

Maintenance: Maximizing Lid Seal and System Life

• Routine Inspection Frequency: We recommend examining lid seals at least at each bag change. Look for cracking, flattening, discoloration, or chemical swelling.
• Replacement Practices: In food, beverage, and pharmaceutical duties, or aggressive chemicals, always change the seal when you change the filter bag. In clean water or HVAC uses, you might get multiple bag changes before needing a new seal, but never ignore damage.
• Spares Management: For each filter housing, keep at least two spare lid seals on hand to ensure process continuity if one is lost, damaged, or shows rapid wear.
• Compatibility Checks for Process Changes: Whenever you change process fluids or cleaning agents, verify the current seal material’s compatibility to avoid sudden degradation.
• Document Everything: Log the date, condition, and cause behind each seal replacement and leak incident. Trend analysis can highlight issues with seal type, or process changes, saving money and downtime over time.

Troubleshooting Leaks: Rapid Response Approach

• Step 1: Shut down, depressurize, and safely drain the housing. Follow housing operating manual. 
• Step 2: Inspect for mechanical damage: feel for nicks, tears, deformation, or chemical attack (soft, swollen, or brittle surface).
• Step 3: Clean the flange and groove, ensuring all surfaces are smooth and undamaged.
• Step 4: Replace with a new, compatible seal, never reuse a damaged one.
• Step 5: If the leak persists, double-check the lid’s fit and closure pattern, and consult with us if repeated failures occur.

Quick Reference Table: Common CLARIBag Housing and Seal Specs

Pro Tips for Longer-Lasting, Leak-Free Lid Seals

• Always source replacement seals that match both your housing model and application (temperature, chemical, food compliance).
• Never force seals during installation—if it feels too tight or loose, check model compatibility.
• Keep all sealing faces clean and inspect for scratches or dents, which can compromise the seal even with a new O-ring.
• Avoid cheap non-genuine spare parts and poorly-stored elastomers—these can fail prematurely, wasting time and risking contamination.

Frequently Asked Questions

• How often should lid seals be replaced?
  It varies by application: in harsh chemical/food service, every bag change. In water and low-stress duties, inspect every few weeks or after noticeable pressure drops.
• Are lid seals food-safe?
  We have food grade seals in our range. Please check with us if the filter materials need to be suitable for food contact. Our FBH Series Hygienic bag filter housings come as standard with food grade Silicone or EPDM seals. 
• How do I know if my seal is failing?
  Look for visible liquid at the closure, sudden loss of pressure, changes in filtrate quality, or physical damage on inspection.