3M Liqui-Cel cleaning & storage

Summary

Product identification

These guidelines are for 3M™ Liqui-Cel™ EXF Series Membrane Contactors.

Intended Use(s)

3M™ Liqui-Cel™ Membrane Contactors are intended to:

• Remove dissolved gases and bubbles from compatible liquids.
• Add gases to a liquid stream.
• Be used in industrial separation applications of industrial fluids.
• Be used in Food and Beverage (F&B) applications (for certain limited Liqui-Cel products, refer to specific product datasheet).
• Create purified water that is processed by distillation or equivalent to create Water For Injection (WFI), but should not be used during the production of WFI after distillation.

Restricted Use(s)

• Any application other than the stated intended use(s) unless prior written authorization from 3M is obtained.
• Any manner whereby the product, or any extractable or leachable from it, may become part of or remain in a medical device, drug, cosmetic, or food or drink additive or supplement.
• Applications involving life-sustaining medical applications or prolonged contact with internal bodily fluids or tissues.
• Do not introduce dangerous (explosive, flammable, toxic or oxidizing) liquids or gases to the contactor or the system.
• Do not allow microporous polypropylene membranes to come into contact with surfactants, oils or organic solvents, such as detergent solutions, enzymatic cleaners, pure alcohols, glycol, acetone, etc., to reduce the risk of membrane wet-out.
• Do not use strong oxidizing agents for cleaning solutions.
• Do not use chemicals that contain detergents or surfactants for cleaning.
• Do not use steam for sanitization.
• Do not use beta or gamma radiation sterilization methods.

Cleaning Parameters

Four parameters affect the cleaning process:

• Time (duration and frequency)
• Temperature
• Mechanical shearing on membrane surface by flowing liquids
• Chemical type (caustic, acid, alcohol, etc.) and chemical strength

Cleaning Solution Flow Rate Guidelines

Cleaning solution flow rates vary by contactor size and whether cleaning the shell side or lumen side. See the official PDF for exact tabulated values.

Recommended Cleaning Procedure for Routine/Preventative Maintenance

For routine cleaning (e.g., weekly or monthly) using filtered water (5-micron absolute):

1. Water flush: 5-15 min, at ambient temperature.
2. Alkaline cleaning: Recirculate NaOH or KOH solution at pH 12, ambient to 40°C, for 30 min to 1 hr (soak optional).
3. Drain and optional water flush for 5 min.
4. Acid cleaning: Recirculate citric, nitric, hydrochloric, or phosphoric acid solution at pH 1, ambient temperature, for 30 min to 1 hr (soak optional).
5. Drain.
6. Water flush: Until effluent pH is acceptable.
7. Drain.

Cleaning Tips: Begin with caustic to remove biofouling. Acid cleaning removes mineral scaling and neutralizes caustic. Reverse flow (back-flow) during cleaning is recommended if possible.

Recommended Cleaning Procedure for Moderate Fouling

This procedure uses higher chemical concentrations and longer durations:

1. Water flush: 5-15 min, 5-micron filtered water, ambient temperature.
2. Alkaline cleaning: Recirculate 2-6 wt.% caustic (NaOH or KOH) solution, ambient to 50°C (122°F), for 30 min to 4 hrs.
3. Drain.
4. Acid cleaning: Recirculate 10 wt.% citric acid, or 1-6 wt.% nitric, phosphoric, hydrochloric, or mixed acid solution, ambient temperature, for 30 min to 2 hrs.
5. Drain.
6. Water flush: Until effluent pH is acceptable.
7. Drain.
8. Gas purge (optional): Blow air or inert gas through lumen side for minimum 15 min or until no water drips out.

Recommended Cleaning Procedure for Severe Fouling

This procedure addresses fouling that has penetrated the membrane pore structure and includes a membrane wet-out step followed by extensive drying:

1. Water flush: 5-15 min, 5-micron filtered water, ambient temperature.
2. Drain.
3. Membrane wet-out: Pressurize shell side with 50 vol% Isopropanol-water or ethanol-water solution (not exceeding max pressure rating). Allow solution to exit lumen ports, then cap lumen ports and soak for minimum 1 hr.
4. Alkaline cleaning: Recirculate 2-6 wt.% caustic (NaOH or KOH) solution, 30-50°C (86-122°F), for 1 to 4 hrs.
5. Drain.
6. Acid cleaning: Recirculate 10 wt.% citric acid, or 1-6 wt.% nitric, phosphoric, hydrochloric, or mixed acid solution, ambient temperature, for 1 to 2 hrs.
7. Drain.
8. Water flush: Until effluent pH is acceptable.
9. Drain.
10. Gas purge (optional): Blow air or inert gas through lumen side for minimum 15 min or until no water drips out.
11. Drying: Thoroughly dry the contactor using the procedure described later in this guide.
12. Integrity test: Perform a membrane and contactor integrity test.

Cleaning Procedure for Mineral Scaling Removal

• Carbonate scaling: Follow the routine cleaning procedure (Table 2) but skip the alkaline cleaning (steps 2 and 3).
• Silica (SiO₂) precipitation: Use the moderate fouling cleaning procedure (Table 3) but with higher caustic concentration (up to 6 wt.%) and increase the temperature to the maximum operating limit of the contactor.

Cleaning Procedure for Particle Blockage in Contactor

This procedure is for 3M™ Liqui-Cel™ EXF Series only (for SP series, only follow steps 1 & 2):

1. Follow sections V and VI guidelines.
2. Backflush cleaning solutions on the shell side (opposite normal operating flow direction) at a maximum liquid inlet pressure of 15 to 30 psig (1 to 2 bar).
3. Valve off or cap one gas port, then slowly introduce clean, dry, oil-free compressed air into the other gas port. Avoid sudden pressure spikes.
4. Regulate air pressure 5-10 psig (0.4 to 0.8 bar) GREATER than the liquid pressure, to vigorously bubble air into the cleaning solution. (Note: During normal operation, liquid pressure should always exceed gas pressure).
5. At the end, shut off air supply first, then slowly open gas outlet port, then stop liquid flow.

Contactor Sanitization

Chemical Sanitization

Chemical sanitization should be limited due to slow membrane oxidation. For daily sanitization, caustic or hot water is recommended.

• Chlorine: 100 ppm for 15 min (Once/month). Use Hypochlorite at high pH only; avoid Chlorine Dioxide.
• Hydrogen Peroxide (H₂O₂): 3% for 15 min (Once/month).
• Peracetic Acid: 50 ppm for 15 min (Once/month).

Hot Water Sanitization (HWS)

Only 3M Liqui-Cel Membrane Contactors with Stainless Steel housings should be used for HWS: EXF-4x13 Series, EXF-4x28 Series, EXF-8x20 Series, and EXF-10x28 Series.

• Water temperature: Max 85°C (185°F).
• Water pressure: Max 2 bar (29 psi).
• Heating/cooling rate: 2-3°C per min. (3-5°F per min.).
• Sanitization time: 30-60 min after reaching sanitization temperature.
• Vacuum/Air sweep: Must be switched off during HWS.
• Inert gas flow (optional):
  • 4x13: 1 lpm
  • 4x28: 1 lpm
  • 8x20: 2 lpm
  • 10x28: 2 lpm
• If using inert sweep gases (nitrogen, CO₂), maintain minimum flow rate. Leave gas outlet port open.
• Recommended minimum flow rate for 10x28 contactor during HWS is 50 gpm.
• After HWS, purge lumenside with sweep gas for 5-10 minutes at <0.5 bar (<7 psi) inlet gas pressure before re-applying vacuum. Mount contactors vertically and pull vacuum from the bottom gas port for optimal draining of condensate.

Membrane Drying

The drying process involves two steps: Bulk Water Removal and Final Drying.

Bulk Water Removal

To quickly remove water, purge the contactor with gas (normally air) at room temperature for a short period (typically <1 hr). Introduce clean, dry, filtered gas (preferably 0.2 micron) through top shellside and lumenside ports. Keep lower lumen and shellside ports open. Stop gas flow when water discharge reduces to a few drips. Recommended maximum air pressure is 10 psig (0.7 bar). See the official PDF for specific air flow rate ranges per contactor size.

Final Drying

Flow clean, dry, oil-free filtered gas (preferably 0.2 micron) into the top shellside port. Warm gas reduces drying time. Nitrogen is preferred; hot air should not exceed 50°C (122°F). After a few minutes, close the lower shell side port. Recommended maximum air pressure is 30 psig (2 bar). See the official PDF for specific air flow rate ranges and recommended durations per contactor size.

Membrane Contactor Integrity Test

This test validates restoration of hydrophobicity and can be performed at any time. It involves mounting the contactor vertically, pressurizing the shell side with water, and measuring the drip rate from the lower lumen side port.

1. Relieve lumenside pressure. Blow-out lumen side with nitrogen or oil-free air. Open lumen ports to atmosphere.
2. Close the shell side outlet valve.
3. Fill shell side with filtered (5-micron abs.) water. Slowly apply 60 psig (4 bar) pressure to the shell side.
4. Measure drip rate from the bottom lumen port for 1 hour. Compare against expected ranges.
5. Release shell side pressure by slowly opening the outlet valve. Drain the contactor.

Expected drip rates from the lumen port during the integrity test (at ambient temperature) vary by contactor size and membrane type (X50, X40, XIND). See the official PDF for exact tabulated values.

If drip rates significantly exceed the expected range, it may indicate membrane wet-out, a fiber break/cartridge damage, or seal failure. Membrane wet-out is typically reversible after cleaning; fiber break/cartridge damage and seal failure may require replacement or re-seating of seals.

Contactor Storage and Handling Guidelines

After cleaning and complete drying:

• Store dry in a sealed plastic bag or shrink wrap material to keep ports closed and prevent contaminants.
• Store at temperatures <49°C (120°F), preferably <35°C (95°F), and always above freezing. Allow to equilibrate to room temperature before use if stored at low temperature.
• Store in original or opaque box, not exposed to direct sunlight.
• Support all plastic port extensions to prevent bending.
• Avoid dropping, hitting, or impacting the contactor. Use appropriately rated lifting equipment.
• Store membrane contactors in the horizontal position.
• Ensure the system is stable, level, and properly secured to prevent tipping, rolling, falling, or sliding.

If drying is not completed, contactors must be stored with preservatives (e.g., Sodium Metabisulfite or dilute caustic solution) on both shell and lumen sides, or under an inert gas (nitrogen or CO₂) at 0.5 bar (7 psig).

Disclaimer

This summary is based on extracted text and may not include all figures, footnotes, or the most recent revisions. For contractual data or complete specifications, please refer to the official OEM PDF revision used on your project.

Official datasheet (PDF)

PDF datasheet