Process Cartridge Filters for Aggressive Chemical Filtration

Selecting the correct cartridge filter and housing combination is therefore critical to achieving safe, reliable, and long-term performance.

This article explains how process cartridge filters are applied in aggressive chemical service, identifies suitable filter media and housing materials, and introduces the use of tantalised housings for the most extreme corrosive environments.

Understanding Aggressive Chemical Filtration

Aggressive chemicals include strong acids, alkalis, and solvents that attack most common materials. Examples include:

• Acids: Sulfuric (H₂SO₄), Hydrochloric (HCl), Nitric (HNO₃), Hydrofluoric (HF)
• Alkalis: Sodium hydroxide (NaOH), Potassium hydroxide (KOH)
• Oxidising agents: Hydrogen peroxide (H₂O₂), Sodium hypochlorite (NaOCl)
• Organic solvents: Acetone, MEK, toluene, DMF

Each of these can rapidly corrode or embrittle polymer or metal housings and degrade filter media if materials are not correctly matched.

Cartridge Filter Options for Aggressive Chemicals

The choice of cartridge depends on the chemical composition, operating temperature, and required purity level.

Filter Housing Materials for Aggressive Chemical Filtration

Filter housings are often the limiting component in chemical filtration systems. Material choice must consider chemical compatibility, temperature, pressure, and mechanical robustness.

Tantalised (Tantalum-Lined) Housings Explained

Tantalising is the process of applying a thin layer (typically 50–100 µm) of tantalum metal to the internal surfaces of a stainless steel housing. This can be achieved through thermal spray, chemical vapour deposition, or explosive bonding.

Tantalum forms a passive oxide film (Ta₂O₅) that is highly resistant to almost all acids — including hydrofluoric acid (HF), which attacks glass, and hot nitric acid (HNO₃), which attacks most metals.

Advantages

• Compatible with virtually all mineral acids, including HF, aqua regia, and mixed oxidisers.
• Maintains mechanical strength of stainless steel with chemical inertness of glass or PTFE.
• Operates at temperatures >200°C and pressures >10 bar.
• Non-contaminating — ideal for fine chemicals, catalysts, and pharmaceutical intermediates.

Limitations

• High capital cost and specialised fabrication.
• Lead times typically longer than standard housings.
• Must avoid physical damage to coating during installation or cartridge change-out.

Typical use cases:

• Mixed acid systems in fine chemical production.
• Hydrofluoric acid filtration in fluoropolymer or catalyst manufacture.
• Concentrated nitric acid recirculation lines.
• High-temperature oxidising or halogenated solvent service.

Matching Cartridge and Housing to Application

System Design and Safety Considerations

1. Seal Materials:

   • FEP-encapsulated Viton®, Kalrez®, or PTFE are preferred.
   • Avoid Buna-N or EPDM in oxidising or solvent environments.
     
   
   

2. Mechanical Integrity:

   • Pressure ratings must exceed operating conditions.
   • For mixed acid systems, use tantalised housings or thick-wall PTFE-lined steel.
   
   

3. Avoid Adhesives:

   • Specify thermally welded or fused cartridge construction to eliminate extractables.
   
   

4. Grounding and Safety:

   • Essential for solvent and flammable chemical systems.
   
   

5. Inspection and Maintenance:

   • Regularly inspect housings — especially lined or tantalised types — for coating damage.
   • Replace filters based on differential pressure rather than time to maintain safety margins.

In aggressive chemical service, chemical compatibility is just as critical as filtration efficiency.

• Polypropylene and PVDF systems are suitable for most acids, alkalis, and oxidisers.
• PTFE and PFA systems deliver the ultimate in chemical inertness and purity.
• And for the most extreme acid mixtures — especially those containing hydrofluoric acid or mixed oxidising acids — tantalum-lined housings provide the only practical long-term solution, combining the strength of stainless steel with the corrosion resistance of glass or PTFE.

By carefully pairing the correct cartridge media and housing construction, engineers can achieve safe, efficient, and durable filtration performance even under the harshest chemical conditions.

You can read more about filtration solutions for Chemicals & Solvents here and if you have any questions then you can give us a call or send us an email - we’d be more than happy to help. 

You can also read more in our blogs:  

• Prefiltration: Choosing The Right Cartridge Filters
  
• Navigating Different Housings for Cartridge Filter Applications
• Guide to Selecting the Right Micron Rating
  

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