Understanding Filtration

Process Cartridge Filters for Aggressive Chemical Filtration

Nov 13, 2025

4 Minutes Read

Aggressive chemical processes place exceptional demands on filtration systems. Whether filtering strong acids, alkalis, oxidising agents, or organic solvents, the filter cartridges and housings must resist chemical attack, maintain mechanical integrity, and ensure product purity

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 Type	Construction	Chemical Resistance	Typical Applications
All-Polypropylene (PP) Depth & Pleated Filters	Melt-blown or pleated PP media with PP hardware	Excellent for most acids, alkalis, and aqueous salts	General chemical blending, acid/alkali filtration, cleaning baths
PVDF Pleated Filters	PVDF membrane or depth media with PVDF hardware	Excellent resistance to oxidisers and many solvents	Oxidising agents, solvent-based blends
PTFE Membrane Filter	Hydrophobic or hydrophilic PTFE membrane with PFA or PP support	Outstanding resistance to virtually all chemicals	Concentrated acids, organic solvents, semiconductor-grade fluids
Sintered St.St.	Rigid porous structure	Chemically inert and mechanically strong	High-solids acids or abrasive chemical processes

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.

Housing Material	Typical Use	Advantages	Limitations
Polypropylene (PP)	Acids, alkalis, aqueous solutions	Low cost, non-metallic, lightweight	Limited to ~80°C; not suited for strong oxidisers or solvents
PVDF (Polyvinylidene Fluoride)	Oxidising agents, strong acids	Excellent oxidiser resistance; clean construction	Moderate pressure limits (~6 bar)
PFA / PTFE	High-purity and semiconductor chemicals	Universal compatibility, inert, ultra-clean	Expensive; limited pressure rating
Glass-Reinforced Polypropylene (GRPP)	Utility and plant service	Improved mechanical strength	Still not compatible with strong oxidisers
PTFE-Lined Stainless Steel	Concentrated acids, solvents	Combines metal strength with PTFE inertness	Lining integrity critical; avoid mechanical damage
Tantalum-Lined (Tantalised) Stainless Steel	Highly corrosive acids including HF, hot HNO₃, mixed oxidisers	Exceptional corrosion resistance rivaling glass or PFA; withstands high pressure and temperature	High cost; longer lead time
Solid Alloy (Hastelloy, Alloy 20, Inconel)	Mixed acid duties and hot oxidisers	High mechanical and thermal strength	Costly and still limited in halide-rich acids (HF, HCl)

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

Application	Typical Chemicals	Recommended Cartridge	Recommended Housing	Notes
Acid Pickling / Metal Finishing	HCl, H₂SO₄, HNO₃	All-PP depth & pleated depth (5–20 µm)	Glass-reinforced PP or PTFE-lined SS	Economical for moderate acids
Caustic Cleaning Baths	NaOH, KOH	All-PP depth depth & pleated depth (1–10 µm)	Polypropylene or GRPP	Compatible, cost-effective
Oxidising Agents	NaOCl, H₂O₂	PVDF pleated (0.5–5 µm)	PVDF housing	Avoid PP; PVDF maintains stability
Organic Solvent Filtration	MEK, toluene, acetone	PTFE membrane (0.2–1 µm hydrophobic)	PTFE or PFA housing	Ensure Kalrez® or FEP seals
High-Purity Acid Supply (Semiconductor)	HF, HCl, H₂SO₄	Hydrophilic PTFE membrane (0.1–0.5 µm)	All-PFA housing	Zero metallic contamination
Pharmaceutical API Synthesis	Mixed solvents and reagents	PVDF or PTFE membrane (0.2–1 µm)	PTFE-lined or tantalised SS housing	Use where oxidisers and solvents are mixed
Fine Chemical Production (Mixed Acids)	HF + HNO₃ + H₂SO₄	PTFE membrane (0.2 µm)	Tantalised SS housing	Handles extreme acid blend; long service life
Etching / CMP Slurries	H₂O₂, NH₄OH, abrasives	PVDF or PTFE hybrid	PFA or PVDF housing	Ensures ultra-clean, particle-free output

System Design and Safety Considerations

Seal Materials:
- FEP-encapsulated Viton®, Kalrez®, or PTFE are preferred.
- Avoid Buna-N or EPDM in oxidising or solvent environments.
Mechanical Integrity:
- Pressure ratings must exceed operating conditions.
- For mixed acid systems, use tantalised housings or thick-wall PTFE-lined steel.
Avoid Adhesives:
- Specify thermally welded or fused cartridge construction to eliminate extractables.
Grounding and Safety:
- Essential for solvent and flammable chemical systems.
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:

PoreFiltration – Making your filtration systems work harder

Process Cartridge Filters for Aggressive Chemical Filtration

Understanding Aggressive Chemical Filtration

Cartridge Filter Options for Aggressive Chemicals

Filter Housing Materials for Aggressive Chemical Filtration