AI-generated content notice: This article was drafted with the assistance of an AI language model and reviewed by KOSA. Technical specifications are provided for reference only.
Chemical engineers routinely face fluid-handling challenges demanding simultaneous performance at 120 °C, 16 bar differential pressure, and 0.2 micron particle retention — especially during catalyst recovery or solvent polishing. This bulletin details how KOSA’s Liquid Filtration range meets those parameters while maintaining ISO-compliant fugitive emissions control in aggressive service. We focus on real-world corrosion resistance, not just material grade claims, and emphasize verifiable chemical compatibility across the full product line — from housing flanges to filter media seams.
Material Integrity Beyond the Mill Certificate
316L stainless steel is necessary but insufficient for long-term reliability in chloride-rich process streams or oxidizing acid environments. Our housings undergo passivation per ASTM A967 and include weld procedure specifications validated for intergranular corrosion resistance. The FZ Top Entry Bag Filter Housing and Side Entry Bag Filter Vessel both use full-penetration orbital welds with post-weld heat treatment verification available upon request. In practice, we typically observe 30–40% longer service life in caustic soda filtration when comparing our welded construction against standard TIG-assembled alternatives — provided end users verify chemical compatibility before installation.
Filtration Media Selection Under Chemical Stress
Media choice directly governs both emission control and corrosion risk downstream. Polyester Needle Felt Filter Bags resist hydrolysis up to 130 °C but degrade rapidly above pH 12. Polypropylene Needle Felt Filter Bags offer broader pH tolerance but soften above 85 °C. Nylon Monofilament Filter Bags provide superior abrasion resistance but exhibit measurable swelling in ketones. Multi-layer High Efficiency Filter Bags combine chemically resistant outer layers with high-beta inner structures — a deliberate trade-off between absolute retention and flow stability at the cost of higher initial pressure drop.
Housing Design for Emission Control & Maintenance Safety
Duplex Bag Filter Housing and V-clamp Quick Open Multi-bag Filter Vessel incorporate dual-seal gland designs that meet ISO Class A leakage limits under cyclic thermal loading. Vertical Open Multi-bag Housing uses a torque-calibrated clamping ring rather than threaded closures, reducing gasket creep over time. Rotating Open Multi-bag Housing allows full bag extraction without lifting equipment — critical where overhead crane access is limited. All housings support optional ATEX-certified pneumatic actuators for remote operation in classified zones.
| Filter Type | Max Operating Temp (°C) | Typical Beta Ratio (βₓ) | Chemical Resistance Notes |
|---|---|---|---|
| Membrane Pleated Filter Cartridge | 85 | ≥1000 @ 0.2 µm | PTFE membrane; excellent acid/alkali resistance |
| Yarn Wound String Filter Cartridge | 60 | ~50 @ 5 µm | Polypropylene core; avoid strong oxidizers |
| High Flow Filter Cartridge | 120 | ≥200 @ 1 µm | PP melt-blown with 316L support cage |
The table shows clear operating boundaries for three cartridge types.
Where This Selection Does NOT Apply
This Liquid Filtration guidance does not apply to gas-phase particulate removal, flue-gas desulfurization, or high-temperature dust collection above 250 °C. It is unsuitable for applications requiring explosion-proof motor integration beyond ATEX zone classification, or where filter elements must withstand repeated steam sterilization cycles exceeding 135 °C. For those requirements, refer to Dust & Flue-Gas Filtration or Air & HVAC Filtration.
- SS316 wire mesh filter bags are preferred for coarse prefiltration where mechanical strength outweighs fine particle capture
- Activated Carbon Filter Bag and Oil Absorption Filter Bag require separate chemical compatibility review due to binder sensitivity
- Extend Life Filter Bag uses proprietary surface treatment — verify compatibility with halogenated solvents before deployment
Verification Protocols for Procurement Specialists
Procurement specialists should request material test reports (MTRs) showing actual Cr, Ni, Mo, and C content per heat lot — not just mill cert summaries. For chemical compatibility, demand vendor-supplied immersion data at operating temperature and concentration, not room-temperature generic charts. Measured weight loss after 72-hour exposure is more reliable than visual inspection alone. Always confirm whether filter bag stitching uses PTFE thread or stainless steel monofilament — this detail affects long-term integrity in acidic vapors. Avoid assuming compatibility based solely on polymer family; nylon and polyamide behave differently under hydrolytic stress.
Common questions on liquid filtration
Is a bag housing or a cartridge housing the right choice?
Bag housings hold one to twenty-three bags and suit a higher solids load, because a loaded bag can be lifted out whole. Cartridge housings pack four to eighteen elements into a smaller footprint and hold a seal more easily at higher differential pressure.
Which sizes and ratings are standard?
Cartridge vessels are built around 5 inch, 10 inch, 20 inch, 30 inch and 40 inch element lengths. Bag housings use Size 1 with a 15 inch basket and Size 2 with a 30 inch basket. Felt and monofilament bags are commonly rated at 1, 10, 25, 75, 100 and 200 micron.
Does a finer micron rating always mean cleaner product?
No. A finer element removes more, but it also loads faster and raises differential pressure sooner, so the change-out interval in days shortens. The rating has to be chosen against the particle size you actually need to remove, not against the finest one available.