Chemical Processing Conditions & Solutions

Gradient of Precision

Material compatibility: initial screening matrix

quick seal assessment

Acidic and Oxidizing Chemicals Service Condition

Grade Product Acid: Tank Transfer and Filling

• Service condition: 5%–98% H2SO4, ambient to moderate temperature; source includes tankers, tanks, and circulation lines.
• Issues: Weld slag, rust particles, salt crystals, and polymer debris entering the finished product; fine filter cartridge rapid pressure rise.
• Identification: Check particle size distribution, iron/metal content, temperature, free SO3, moisture content, and batch solid load.
• Solution: inlet basket strainer → high-capacity coarse filtration → depth filter cartridge → fine filtration before filling; for high-solids fluids, use settling or a bypass circulation loop first.
• Accuracy / Structure: 100–300 μm screen; 20–50 μm depth; PP absolute grade terminal. High purity grade is tightened according to particle specifications. (5–10 μm)
• Materials: PP may be screened for dilute acids at ambient temperature. For concentrated acids, hot acids, or low-extractables requirements, prioritize a PTFE membrane with PFA support. Verify every seal material individually.
• Acceptance: Particle count or weight at inlet and outlet; clean pressure difference, final pressure difference, single batch flux, and metal blank.
• Boundary: It is not sufficient to validate only the membrane. The support layer, end caps, adhesive, housing, and O-rings all come into contact with acid.

Ultra-pure Sulfuric Acid: Submicron Particle Control

• Operating Conditions: Concentrated sulfuric acid is cooled, diluted, or circulated before entering high-purity packaging; the goal is to achieve extremely low particle and metal extraction.
• Issue: the nominal pore rating is acceptable, but the downstream particle count does not decrease; possible causes include initial cartridge shedding or changes in pore structure after acid exposure.
• Identification: Use actual acid testing to identify ≥0.3/0.5 μm particle and metal blanks, pre-rinse volume, circulation time, and temperature.
• Solution: PFA/pure fluoropolymer system → graded PTFE membrane → final filter cartridge at packaging point; start at low flow rate and circulate until stable.
• Precision / Structure: Pre-stage 0.2–1 μm; terminal 0.05–0.1 μm, advanced technology capable of nanometer-level precision, but must be defined by particle removal efficiency.
• Material: PTFE membrane; PFA or validated UPE/HDPE support, end caps, and housing; FFKM or PTFE-coated seals.
• Acceptance: Actual acid PRE, effluent particle stability time, metal leaching, 28-day soak or equivalent accelerated testing.
• Limitations: Water-rated values cannot directly replace performance in hot concentrated sulfuric acid.

Hydrochloric Acid: Preparation, circulation, and terminal filling.

• Conditions: 5%–37% HCl; steel upstream may introduce corrosion products, absorption/dilution process may release particles.
• Issues: Brownish-yellow iron impurities, black spots, pipeline corrosion flakes; pitting of stainless steel housing leading to secondary contamination.
• Identification: Confirm concentration, temperature, free chlorine, metal limits, housing material, and whether continuous circulation is in place.
• Solution: Corrosion-resistant basket → 10–25 μm depth filtration → 1–5 μm absolute grade; high-purity products may require additional 0.1–0.2 μm terminal.
• Precision / Structure: 50–100 μm coarse filter; 10 μm protection; 1–5 μm finished product; electronic grade select 0.05–0.2 μm based on particle specifications.
• Materials: PP, PVDF, or PTFE membranes; high purity/temperature applications prioritize fully fluorinated structures. Avoid unverified 316L wet contact components.
• Acceptance: Particles, iron/nickel/chromium, differential pressure curve, visual and quality changes after soaking.
• Limitations: Concentration and temperature can alter compatibility; different formulations of the same material may vary.

Nitric Acid: Strong Oxidizing Acid Filtration

• Conditions: 20%–68% HNO3, may contain NOx; commonly used in metal treatment and high purity wet chemistry applications.
• Issues: General PP, nylon, PES, or elastomer oxidation, brittleness, discoloration, shedding; metal housing corrosion.
• Identification: Check concentration, temperature, fuming grade, mixed acid composition, and exposure duration; perform sealed soaking and differential pressure maintenance.
• Solution: Enclosed fully fluorinated tubing → PTFE/PFA coarse filtration or graded membrane filtration → final point filtration.
• Accuracy / Structure: 10–25 μm for protection; 1–5 μm for industrial grade final filtration; high purity 0.05–0.2 μm.
• Materials: PTFE membranes with PFA support/shell preferred; FFKM or PTFE coated seals.
• Acceptance: Quality, dimensions, bubble point/integrity, particle and metal leaching before and after soaking; validate maximum temperature.
• Hazards: Nitric acid reacts with flammable materials, alcohol, and metal powders. Do not use general solvent compatibility tables as a substitute for risk assessment.

Phosphoric Acid: Wet Process Acid Clarification and Commercial Acid Filtration

• Conditions: Wet H3PO4 with gypsum, silica gel, and mine mud; low solid load for purification or food/electronic grade acid.
• Issue: Colloids and fine gypsum form a compact filter cake; 1 μm cartridge will quickly clog if used directly.
• Identification: Measure solid concentration, particle size, viscosity, temperature, fluorosilicate components, and whether there is continuous crystallization.
• Solution: Sedimentation/settling → 50–100 μm coarse filtration → 10–25 μm depth filtration → 1–5 μm final filtration. Molecular/metal separation with NF (nanofiltration) as needed.
• Accuracy/Structure: High solid 50–200 μm; protective 10–25 μm; low solid final 1–5 μm.
• Materials: PP, PVDF, PTFE can be used for initial screening; prefer fully fluorinated structures for high temperature and fluorine-containing systems.
• Acceptance: Turbidity, filterable solids, P2O5 loss, pressure drop, and filtrate liquid content.
• Boundary: Pleated filter cartridges cannot replace the gypsum primary separation equipment; NF still requires long-term stability validation for concentrated phosphoric acid.

Hydrofluoric Acid and Fluorine-containing Etchants

• Operating Conditions: Dilute HF, concentrated HF, buffered HF, or fluorine-containing mixed acids; commonly used for surface treatment and electronics manufacturing.
• Issues: Glass fiber pre-filter layer or silicon-containing materials are eroded; metal wet parts leach out; metal and particle content in the final product exceed limits simultaneously.
• Identification: Confirm HF concentration, buffer salts, temperature, metal limits, and all wet contact materials.
• Solution: Non-glass fiber coarse filtration → full-fluorine precision filtration → POU terminal; reduce metal joints and dead ends.
• Accuracy/Structure: 5–20 μm protection; 0.1–1 μm final product; high-purity process 0.02–0.1 μm.
• Materials: PTFE/PFA preferred; PVDF, PP, or UPE are validated for specific concentrations and temperatures; avoid glass fiber.
• Acceptance: Fluoride content unchanged, particle/metal content decreases, immersion integrity and effluent TOC.
• Boundary: Mixed acids are judged by the most stringent component; membrane compatibility does not imply compatibility of the housing and seals.

Hydrogen Peroxide, Peroxyacids, and Oxidizing Formulations

• Operating Conditions: Hydrogen Peroxide, Peroxyacetic Acid, or Oxidizing Cleaning Solutions; Decompose Easily and Release Gases.
• Issues: Catalytic Metals or Filter Materials Accelerate Decomposition; Bubbles Cause False Pressure Differences and Flow Fluctuations.
• Identification: Measure Concentration, Stabilizers, Metal Impurities, Temperature, Gas Release Rate, and Activity Before and After Filtration.
• Solution: Low Metal PTFE/PFA System → Graded Particle Filtration → Low Shear Terminal; Set Up Safe Venting and Pressure Differential Interlocks.
• Accuracy / Structure: 5–10 μm Protection; 0.2–1 μm Terminal; Further Tightening Possible for Electronic Grade.
• Materials: PTFE/PFA Preferred; Seals Must Be Chosen Based on Oxidant Concentration and Temperature.
• Acceptance: Activity Content, Particles, Metal Impurities, Bubble Point/Diffusion Flow, and Decomposition Rate.
• Boundaries: Do Not Use Filters as Stabilizers; Avoid Catalytic Contamination from Metals Like Copper and Iron.

Glacial Acetic Acid and Acetic Acid Solutions

• Operating Conditions: 5%–99.8% Acetic Acid; Water content determines membrane wetting, polymer swelling, and sealing performance.
• Issue: Ice acetic acid is not friendly to certain nylon, cellulose, PES, and elastomers; filtrate may show extract peaks or odor changes.
• Identification: Record concentration, water content, temperature, residence time, downstream purity, and allowable organic extracts.
• Solution: 25–50 μm coarse filter → 5–10 μm depth → 0.45–1 μm fine filter; for dilute solutions requiring microbial control, add 0.2 μm.
• Accuracy/Structure: Industrial clarification 5–25 μm; fine chemical 0.45–5 μm; bioburden reduction 0.2/0.22 μm and requires validation.
• Materials: PTFE/PFA is most stable; PVDF, PP are used only within specific concentration/temperature windows. Seals should be FFKM/PTFE coated.
• Acceptance: Acidity, water content, color, GC non-volatiles, pressure drop, and post-filter extracts.
• Boundaries: Dilute acetic acid can support microbial growth; the primary target of ice acetic acid is typically particulate matter, not bioburden reduction.

Citric Acid, Lactic Acid, Formic Acid, etc. Organic Acids

• Operating Conditions: Water solutions, fermentation-derived crude liquids or refined products; may contain cells, salt precipitation, and colloids.
• Issue: High load directly on the membrane causing blockage; some membranes adsorb the target substance or release trace metals.
• Identification: Distinguish between synthetic and fermentation liquids; measure solids, viscosity, pH, metals, microorganisms, and active recovery.
• Solution: Centrifugation/Ceramic MF → 10–25 μm depth → 1–5 μm polishing; water-based final bioburden reduction can use 0.2 μm.
• Accuracy/Structure: Fermentation crude liquid 0.1–0.5 μm crossflow MF; dead-end protection 10–25 μm; final 0.2–1 μm.
• Materials: PP, PES, PVDF or PTFE selected based on acid type, concentration, and temperature; formic acid prefers PTFE.
• Acceptance: Yield, color, metals, microorganisms, integrity, and unit area throughput.
• Limitations: Fermentation solid-liquid separation cannot rely on small capsule filters.

Waste acid and acid wash tank liquid recovery

• Conditions: HCl, H2SO4, HNO3/HF, or H3PO4 acid wash solutions, containing metal ions, scale, and oil.
• Issue: Suspended solids clog ion exchange, diffusion dialysis, or NF; oil film reduces flux; metal salts continuously accumulate.
• Identification: Separately measure suspended solids, free acid, Fe/Cr/Ni, oil, temperature, and acid recovery targets.
• Solution: Oil removal/settling → 10–50 μm coarse filtration → 1–5 μm protection → diffusion dialysis/acid blockage/NF.
• Accuracy / Structure: Pre-treatment with 10–50 μm; membrane device protection with 1–5 μm. Ion separation accuracy is expressed in retention rate/MWCO, not in microns.
• Materials: Front-end can use PP/PVDF/PTFE; main separation membranes must undergo long-term stability testing in mixed acids.
• Acceptance: Free acid recovery rate, metal retention, membrane flux, acid consumption, and waste volume.
• Limitations: Pleated filter cartridges can remove particles but cannot separate dissolved metals from the acid.

Organic Solvents and Reaction Solutions

Alcohol Solvents: Methanol, Ethanol, IPA, Butanol

• Conditions: Solvent refining, reaction mixing, extraction, or final packaging; some are flammable liquids.
• Issues: Tank corrosion, activated carbon dust, and pipeline particles; moisture or temperature drop causing salt or polymer precipitation.
• Identify: Determine moisture content, viscosity, flash point, particles, non-volatile residues, and microbial limits of the target microorganisms.
• Solution: 50–100 μm coarse filtration → 5–10 μm depth filtration → 0.2–1 μm fine filtration; use PTFE for low water-soluble solvents to facilitate wetting.
• Accuracy/Structure: General-purpose finished 1–5 μm; analytical/electronic-grade 0.05–0.45 μm; bioburden reduction 0.2 μm requires product validation.
• Materials: PTFE, PP, PVDF commonly used; for PES/Nylon, confirm based on specific alcohols and concentrations. Validate housing, tubing, and seals together.
• Acceptance: Particle count, turbidity, GC purity, moisture content, integrity, and pre-rinse volume.
• Boundaries: Implement explosion-proof zone execution, bridged grounding, and inerting requirements; filtration can generate static electricity.

Ketones: Acetone, MEK, cyclohexanone.

• Conditions: Low viscosity flammable solvents for cleaning, resin, and paint formulation.
• Issues: PTFE, some PVDF, and FKM may swell or fail with PES; seal leakage may occur before membrane failure.
• Identify: Confirm single or mixed solvents, moisture content, temperature, cycle duration, and allowable extractables.
• Solution: 25–50 μm inlet → 5 μm depth filtration → 0.2–1 μm PTFE fine filtration; use full PP/PTFE capsule assemblies for small batches.
• Accuracy/Structure: Coarse filter 25–50 μm; final product 1–5 μm; high cleanliness 0.1–0.45 μm.
• Materials: PTFE membranes preferred; PP or PFA support/casing. Ketone seals preferred: EPDM, FFKM, or PTFE-coated, do not default to FKM.
• Acceptance: 24–168 h immersion, dimensional/hardness change, gas-tightness, pressure differential, and GC extractables.
• Boundary: Re-evaluate upon the introduction of aromatics or amines; static immersion cannot replace thermal pressure cycling.

Aromatics and hydrocarbons: toluene, xylene, hexane, heptane

• Operating conditions: resins, paints, extraction and reaction solvents; non-polar, flammable.
• Issues: PP or EPDM may swell; high surface tension differences may cause flow prediction errors.
• Identification: Verify the aromatic/aliphatic ratio, temperature, flash point, viscosity, dissolved resin content, and sealing material.
• Solution: 50–100 μm coarse filtration → 10 μm depth filtration → 1–5 μm final product; for coating or fine finishing, add 0.2–0.45 μm.
• Accuracy / Structure: General 1–25 μm; High Cleanliness 0.1–0.45 μm.
• Material: PTFE membrane preferred; PFA, validated nylon, or PVDF optional. Seals often screened with FKM/FFKM/PTFE coating.
• Acceptance: Color, particles, non-volatiles, seal volume change, pressure difference, and flow rate.
• Boundary: The filtration system must be electrostatic dissipative; non-conductive plastic housings do not automatically eliminate the risk of static electricity.

Esters and Ethers: Ethyl acetate, THF, dioxane.

• Conditions: Reaction, extraction, resin, and electronics; some solvents have high permeability.
• Issue: Membrane layer compatibility, but support polyester or binder swelling; a sudden increase in flow rate often signals damage to the pore structure.
• Identification: Confirm solvent purity, peroxides, moisture content, temperature, cycle duration, and resin formula.
• Solution: 25–50 μm coarse filter → 5 μm full PP depth → 0.2–1 μm PTFE; continuous recovery preceded by 1–5 μm protection.
• Accuracy / Structure: General terminal 0.45–5 μm; electronic/analytical grade 0.05–0.2 μm.
• Materials: PTFE membrane; PFA or validated PP housing. Individual sealing and plastic components are tested with THF and other solvents.
• Acceptance: Bubble point/flow, GC purity, TOC/non-volatile residues, and seal leakage after soaking.
• Boundary: Ether peroxides pose a risk independent of filtration, and must be managed separately.

Halogenated solvents: Dichloromethane, chloroform, trichloroethylene.

• Conditions: Extraction, cleaning, and fine chemical reactions; high density, strong volatility.
• Issues: Most ordinary plastic housings and elastomers swell rapidly; bypassing, cracking, and leaching occur.
• Identification: Perform short and long-term component immersions; record temperature, pressure, vapor exposure, and seal compression.
• Solution: Metal or PFA sealed system → 10 μm protection → 0.2–1 μm PTFE terminal.
• Accuracy/Structure: Coarse filter 10–25 μm; terminal 0.2–1 μm.
• Materials: PTFE membrane with PFA wet components preferred; FFKM/PTFE encapsulated seals. Ordinary PP capsule housings require caution.
• Acceptance: weight/size changes, airtightness, solvent purity, extractables, and integrity.
• Limitations: Avoid extrapolating the short-term compatibility of laboratory needle filters to continuous production.

Polar Non-protic Solvents: DMF, DMSO, NMP, Acetonitrile

• Operating Conditions: Polymer dissolution, electrochemistry, synthesis, and extraction; causes significant swelling of the membrane and support layer.
• Issues: Different conclusions for PES/PVDF materials in various datasheets; flow drift, leaching, or component adsorption.
• Identification: Must be tested with actual mixtures; record moisture content, solutes, temperature, residence time, and reuse cycles.
• Solution: 10–25 μm protection → 1–5 μm depth filtration → 0.1–0.45 μm PTFE; use molecular separation with OSN.
• Accuracy / Structure: Particle control with 0.1–5 μm; use MWCO/solute retention for OSN, not micrometer equivalents.
• Materials: use PTFE/PFA as the initial preference. Use PP or nylon only after compatibility testing with the actual process liquid has passed.
• Acceptance: stable flow, bubble point/integrity, solvent purity, target recovery, and membrane quality changes.
• Boundary: Changes in moisture content simultaneously alter solubility, membrane swelling, and filtration flux.

Water–organic solvent mixtures with low concentration preservative formulations

• Operating conditions: Water-based formulations containing alcohols, acetonitrile, or other organic phases; may support microbial growth. (5%; 70%)
• Issue: Low flow due to insufficient wetting of hydrophobic PTFE; active ingredients adsorbed; 0.45 μm mistakenly used for bioburden reduction.
• Identification: Measure water/solvent ratio, surface tension, microbial load, active content, and pre-filter viscosity.
• Solution: 5 μm pre-filter → 0.45 μm bioburden control → 0.2/0.22 μm terminal; perform bacterial retention and integrity testing based on actual liquid conditions.
• Accuracy/Structure: Pre-filter 1–5 μm; terminal bioburden reduction 0.2/0.22 μm absolute grade.
• Materials: Hydrophilic PTFE, PES, or PVDF as per formulation; prioritize PTFE for high organic content.
• Acceptance: Active recovery, microbial challenge, integrity, extractables, and maximum filtration time.
• Boundary: 0.2 μm does not remove all viruses and mycoplasmas; do not assume sterility based on pore size rating alone.

Crystal Precursors and Catalyst/Particle Fine Powder

• Condition: The mother liquor after the reaction contains crystal nuclei, catalyst powder, activated carbon, or salt; the solvent may be alcohol, ester, ketone, or DMF.
• Issue: Fine crystal breakthrough or continued growth within the filter cartridge; temperature drop causing instantaneous blockage of the filter cartridge.
• Identification: Obtain data on particle size, solubility curve, solid content, viscosity, and product loss at both hot and cold conditions.
• Solution: Heat preservation settling/centrifugation → 25–100 μm coarse filtration → 1–10 μm fine filtration; solvent recovery can be connected to OSN/distillation.
• Accuracy/Structure: Crystal recovery based on particle size using 10–100 μm; mother liquor protection using 1–10 μm.
• Material: The filter material is determined by the solvent; high-temperature solvents prefer metal or fluoropolymer structures.
• Acceptance: Filtrate solid content, product yield, crystal morphology, pressure difference, and batch-to-batch stability.
• Boundary: The filtration temperature must be above the critical point where undesirable crystallization is not desired, or it should be designed for controlled crystallization.

Homogeneous Catalyst Recovery and Solvent Purification

• Operating conditions: Precious metal or organic metal catalytic reactions; catalysts and products are dissolved in the organic phase.
• Issue: Microfiltration cannot separate dissolved catalysts; residual metals affect product purity and subsequent reactions.
• Identification: Compare catalyst/product molecular weight, solvent, target retention rate, flux, and membrane long-term swelling.
• Solution: 1–5 μm protective filter cartridge → OSN concentration/dialysis → catalyst reuse; multiple stages may be necessary.
• Accuracy/Structure: Protective filter cartridge 1–5 μm; main separation by MWCO 150–1000 Da and measured retention rate.
• Materials: Pre-filter PTFE/PP; OSN membrane selected based on solvent, pH, and catalyst ligand.
• Acceptance: Catalyst retention, product recovery, metal leakage, solvent flux, and cycle activity.
• Boundary: Pleated filter cartridges only protect OSN, not molecular-level separation.

Chemical formulations and high-purity applications

Coatings, paints, and solvent-based resins

• Operating conditions: solvent-based resins, clear lacquers, or low pigment coatings; containing gels, metal shavings, and skin.
• Issue: Fine filtration can retain effective resin and cause rapid pressure buildup; gels can deform and pass through the filter bag.
• Identification: Measure viscosity, gel hardness, target film thickness, nozzle size, color, and batch solids content.
• Solution: 100–300 μm self-cleaning/screen → 25–80 μm absolute grade → 5–25 μm depth filtration before bottling.
• Accuracy / Structure: ordinary clear lacquer 25–80 μm; high gloss/thin coating 5–25 μm; do not blindly use 1 μm.
• Materials: PP, polyester, nylon, or PTFE based on solvent selection; housing must meet explosion-proof and grounding requirements.
• Acceptance: Scraper fineness, black spot/gel count, viscosity, color, and coating defects.
• Limitations: If the target formulation contains pigments, the filter pore size must be larger than the effective pigment particle size distribution.

High-viscosity resins, adhesives, and sealants

• Operating conditions: viscosity ranging from hundreds to tens of thousands of mPa·s; impurities are mainly rubber pieces, clumps, and metal shavings.
• Issue: Excess differential pressure on conventional pleated membrane; gel deformation and penetration due to pump shear.
• Identification: Record working temperature viscosity, yield stress, pump type, differential pressure, gel morphology, and allowable product loss.
• Solution: Insulation/low shear transport → 100–500 μm basket filter → 25–100 μm wedge filter or depth media.
• Accuracy/Structure: Coarse filter 100–500 μm; final filter 25–100 μm; low viscosity transparent resin can be tested with 5–25 μm.
• Materials: Metal screen, PP polyester depth or PTFE, select based on solvent and temperature.
• Acceptance: Gel count, extrusion/coating defects, viscosity changes, flux at unit pressure difference.
• Limitations: Small area capsule membranes are generally unsuitable for high viscosity high solid primary filtration.

UV-curable ink and functional inks

• Conditions: Dye-based or nanomaterial pigments; nozzles are sensitive to submicron particles and soft gels.
• Issue: Nozzle blockage, line breaks, satellite droplets; membrane adsorption of dye or retention of effective pigments.
• Identification: Obtain nozzle diameter, pigment D90/D99, agglomerates, viscosity, surface tension, and color tolerance.
• Solution: 3–10 μm depth filtration → 0.45 μm membrane filtration → 0.2/0.22 μm final filtration; allow for effective particle size for pigment ink.
• Accuracy/Structure: Dye ink typically uses 0.2–0.45 μm; nanoparticle ink typically uses 0.45–2 μm, with color strength recovery verified.
• Materials: PTFE, nylon, PES or PP selected based on carrier solvent and adsorption risk; capsules may be used for small batches.
• Acceptance: particle size distribution, color difference after filtration, spray pattern, break rate, pressure drop, and flux.
• Limitations: The pore size should be smaller than the clogging particles but larger than the effective pigment clusters; do not rigidly apply 0.2 μm.

Dyes, Pigment Dispersions, and Color Pastes

• Conditions: Dye solutions or pigment suspensions; may contain undissolved powders, grinding media, and agglomerates.
• Issues: Filter pore size too small causing reduced coloring strength; too large leading to nozzle, coating, or fiber defects.
• Identification: Distinguish between soluble dyes and dispersed pigments; measure D90/D99, hard particles, viscosity, and color strength.
• Solution: 100 μm screen → 10–50 μm depth/absolute grade; dissolved dyes can be reused with 0.45–5 μm.
• Precision / Structure: Dispersed Pigment 5–50 μm; Dye Solution 0.45–10 μm.
• Material: PP, Nylon, Polyester, or PTFE, selected based on carrier and adsorption tests.
• Acceptance: Color difference, color strength, hard particle count, viscosity, and filtration loss.
• Lower limit set based on product particle size distribution, not on competitor's nominal pore size.

Agricultural Formulations: EC, SL, SC, and Suspensions

• Operating Conditions: Emulsifiable Concentrates, Soluble Liquids, Suspensions, or Microemulsions; containing active ingredients, adjuvants, solvents, and water.
• Issue: Clogging of nozzles; adsorption of active ingredients by the filter medium; reduction in the concentration of suspended agents after excessive filtration.
• Identification: Identify the dosage form, dissolution/suspension state of active ingredients, D90, nozzle size, temperature, and concentration tolerance.
• Solution: EC/SL: 25–50 μm coarse filter → 5–20 μm final product; SC: 50–150 μm screen, only removing hard agglomerates.
• Accuracy/Structure: EC/SL typically uses 5–25 μm; SC typically uses 50–150 μm, set according to effective particle D99.
• Material: PP, polyester, nylon, or PTFE based on measured compatibility with solvents and additives.
• Acceptance: Active ingredient content, particle size, emulsion/suspension stability, nozzle clogging, and color.
• Boundary: 0.2 μm is not suitable for most suspended agent main filtration.

Surfactants, detergents, and aqueous chemical formulations

• Conditions: High foam, aqueous formulations with fragrances/salts/thickeners; may contain microorganisms and gels.
• Issues: Pump suction causes foam formation and false pressure drop; thickeners clog the membrane; fragrances precipitate.
• Identification: Measure viscosity, haze point, salt content, foam, microorganism count, and active ingredient recovery.
• Solution: Low shear pump → 25–100 μm coarse filter → 5–20 μm depth filtration; low viscosity finished products can add 0.45–1 μm.
• Accuracy / Structure: General 5–50 μm; Bioburden reduction for low solid aqueous products 0.45–1 μm; Bioburden reduction 0.2 μm.
• Materials: PP/PES/PVDF can be used as an initial screening; switch to PTFE and perform adsorption tests when containing fragrances or solvents.
• Acceptance: Active content, foam, turbidity, microbiology, pressure difference, and bubble exclusion time.
• Limitations: For high viscosity formulations, improve process temperature and pre-treatment first, do not rely on increasing membrane area to push through.

Electroplating Solutions, Etchants, and Surface Treatment Tanks

• Operating Conditions: Acidic or alkaline electroplating solutions containing metal salts, additives, anode slimes, and particles.
• Issue: Coarse particles causing pinholes/pitting; activated carbon powder breakthrough; fine filter media adsorbing brightener.
• Identification: Measure particles, metal salts, additives, pH, temperature, circulation ratio, and bath life.
• Solution: Pump circulation → 20–50 μm anode mud coarse filter → 1–10 μm polishing; add 1–5 μm protection after activated carbon treatment.
• Precision/Structure: Ordinary electroplating 1–10 μm; sensitive appearance process 0.5–5 μm; ion separation requires NF/dialysis.
• Materials: PP, PVDF, PTFE, or chemically resistant metal housing; validated according to acid-base and additive combinations.
• Acceptance: Hull Tank/Visual Inspection, Particles, Additives Content, Pressure Differential, and Tank Fluid Stability.
• Limitations: Filtration cannot remove dissolved metal impurities; activated carbon and ion exchange are different mechanisms.

Photoresist, Developer, and High-Purity Wet Chemicals

• Operating Conditions: Photoresist, Diluents, Developer, Cleaning Acids/Bases; Defect Targets Enter the Nanoscale.
• Issues: Metal/organic leaching from filter media, initial particles, and gel precursors causing wafer bridge defects.
• Identification: Measure actual wafer defects, particles, metal/TOC, pre-rinse of filter cartridges, and stabilization time.
• Solution: Tank Circulation Fine Filtration → POU Final Filtration; Low Pressure, Adequate Contact Time, and Control Pre-Rinse.
• Accuracy/Structure: Photoresist Often 0.005–0.04 μm; Wet Chemistry Often 0.02–0.2 μm, Verified by Actual PRE and Defects.
• Materials: UPE/HDPE, PTFE, Nylon, or PFA; Formulations Require Individual Evaluation for Selective Adsorption.
• Acceptance: Wafer Defects, Outflow Particles, Metal/organic Leaching, Flow Rate Decline, and Batch-to-Batch Consistency.
• Limitations: Smaller pore sizes are not always better; the morphology, cleanliness, and adsorption mechanisms also affect defects.

Lithium-ion battery electrolyte

• Operating conditions: Carbonate solvent, electrolyte salt, and additive mix; sensitive to moisture, particles, and metals.
• Issues: Filtration material releases water/metal; fine particles enter the cell; acidic decomposition products render common materials ineffective.
• Identification: Confirm moisture, acidity, particles, metals, viscosity, and additive adsorption in a dry environment.
• Solution: Raw material pre-filtration → mixing cycle → 1–2 μm protection → 0.45–1 μm final → aseptic filling.
• Accuracy / Structure: Specify the 0.45–2 μm from public technical documentation; final accuracy based on cell particle specifications and flux validation.
• Materials: PTFE/PFA or validated PP; low water release, low metal release, and no binder structure.
• Acceptance: Karl Fischer moisture, acidity, particles, metals, additive content, and post-filtration electrochemical testing.
• Limitations: Do not directly use aqueous pressure difference data; electrolyte viscosity, wetting, and electrostatic properties differ.

Small Batch Blending and Sample Final Capsule Filtration

• Conditions: 1-200 L batches for small-scale production, R&D scaling, filling, or single-use tubing; frequent changeovers.
• Issues: Residual contamination from stainless steel housing; small capsule area leading to high pressure drop and product retention.
• Identification: Specify batch size, time, viscosity, solid load, allowable retention, interfaces, and disposal requirements.
• Solution: 5–20 μm small pre-filtration capsule → 0.2–5 μm final capsule; high solid content should be centrifuged or filtered in bags first.
• Accuracy/Structure: Pre-filter 1–20 μm; final filter 0.1–5 μm; typical small capsule area is 0.07–0.55 m².
• Materials: PTFE/PP/PES/Nylon based on medium; prefer hot-melt adhesive-free structure. Interfaces should be NPT, hose clips, or sanitary clamps.
• Acceptance: Batch recovery rate, empty volume, pressure drop, integrity, and extractables from one-time components.
• Boundary: Capsule shell is usually PP/Polyester, which may fail before PTFE membrane.

Solvent Tank Venting and Process Gas

• Operating Conditions: Tank nitrogen seal, breathing gas, pressurized gas, or aseptic ventilation; gases may carry liquid droplets.
• Issue: Hydrophilic membranes clogged by condensate; solvent vapor causing swelling of the support layer; risk of static electricity and flammable gases.
• Identification: Confirm the gas, solvent vapor, dew point, temperature, differential pressures in both directions, and whether microbial retention is required.
• Solution: Fog/condensation control → 0.2 μm hydrophobic PTFE gas filter → redundant or in-place integrity test configuration.
• Accuracy / Structure: General gas bioburden 0.2 μm; particulate protection 0.45–1 μm.
• Materials: Hydrophobic PTFE; housing and seals compatible with vapor. Requires electrostatic discharge design and grounding.
• Acceptance: Diffusion flow, pressure retention, gas flow, condensate management, and breathing pressure differential.
• Boundaries: Liquid ingress can cause a sudden drop in gas flow; positive pressure nitrogen seal requires oxygen deficiency risk control.

Fault Diagnosis Usage