How to Choose the Right Capsule Filter
Capsule filter selection starts with the membrane material, process fluid,
required pore size and application. PES, PTFE, PVDF, Nylon and
Polypropylene membranes behave differently, so the correct capsule depends on
whether the process involves aqueous liquids, proteins, solvents, sterile gases,
venting or particulate prefiltration.
Filtra International supplies disposable capsule filters for laboratory testing,
pharmaceutical and biotechnology process development, pilot-scale filtration,
single-use assemblies and low-volume industrial filtration.
Aqueous liquids
PES Capsule Filters
Hydrophilic polyethersulfone membrane with low protein adsorption.
Commonly selected for aqueous liquids, buffers, process solutions,
pharmaceutical development and biotechnology applications.
View PES capsule filters →
Gas · vent · solvents
PTFE Capsule Filters
Hydrophobic PTFE membrane for gas, air, venting and compatible solvent
filtration where chemical resistance and hydrophobic behaviour are required.
View PTFE capsule filters →
Steam-in-place
SIP PTFE Capsule Filters
Capsule format designed for applications requiring steam-in-place
sterilisation, including sterile air, gas, vent and selected
pharmaceutical or biological processes.
View SIP PTFE filters →
Low protein adsorption
PVDF Capsule Filters
Hydrophilic PVDF membrane with low protein adsorption for compatible
aqueous and process liquids where product recovery and clean filtration
are important.
View PVDF capsule filters →
Aqueous · alcohol
Nylon Capsule Filters
Naturally hydrophilic Nylon membrane for aqueous solutions and compatible
alcohol-containing process fluids, laboratory work and fine chemical
applications.
View Nylon capsule filters →
Prefiltration
Polypropylene Capsule Filters
Polypropylene media for particle reduction, clarification and prefiltration
where larger suspended solids should be removed before a finer downstream
membrane stage.
View PP capsule filters →
Capsule Filter Membrane Comparison
| Membrane |
Surface behaviour |
Typical use |
Available pore-size range* |
Selection reason |
| PES |
Hydrophilic |
Aqueous liquids, buffers, biotech and pharma process liquids |
0.03–5.0 µm |
Low protein adsorption and easy wetting with aqueous liquids |
| PTFE |
Hydrophobic |
Air, gas, tank venting, solvents and compatible chemicals |
0.05–0.65 µm |
Hydrophobic behaviour and broad chemical compatibility |
| SIP PTFE |
Hydrophobic |
Sterile gas, venting and SIP process applications |
Configuration-dependent |
Designed for processes requiring steam-in-place sterilisation |
| PVDF |
Hydrophilic |
Proteins, biotechnology liquids and compatible process solutions |
0.1–3.0 µm |
Low protein adsorption and clean liquid filtration |
| Nylon |
Hydrophilic |
Aqueous liquids and compatible alcohol-containing solutions |
0.1–3.0 µm |
Hydrophilic membrane with alcohol resistance |
| Polypropylene |
Depth / particle filtration |
Clarification, particle reduction and membrane prefiltration |
0.3–30 µm |
Cost-effective removal of larger particulate contamination |
*Pore-size note: available ratings depend on membrane type,
capsule format and exact configuration. For pharmaceutical or validated
applications, pore size alone must not be interpreted as proof of
sterilizing-grade performance.
0.2 Micron Capsule Filters
0.2 µm capsule filters are frequently specified for fine
filtration and critical process development. PES, PTFE and other membrane
materials can be available around this pore size, but their applications
differ significantly.
Hydrophilic PES is commonly selected for aqueous liquid filtration, while
hydrophobic PTFE is commonly selected for gas, air, tank vent and compatible
solvent applications. A membrane should therefore be selected according to
both its pore rating and its material characteristics.
Where a pharmaceutical application requires validated microbial retention,
the specific filter grade, integrity-test limits and supporting validation
documentation must also be confirmed.
Capsule Filters for Pharmaceutical and Biotechnology Processes
Disposable capsule filters are particularly useful during pharmaceutical
development, filtration trials, pilot-scale work and single-use processing.
Their self-contained design allows membrane filtration to be evaluated
without installing a permanent cartridge-filter housing.
Process development
Small-scale filtration trials can be used to evaluate membrane
compatibility, throughput, fouling behaviour and suitable pore size
before production scale-up.
Biotechnology
PES and low-binding membrane options can be evaluated for buffers,
culture-related process liquids, biological solutions and other
compatible aqueous applications.
Sterile gas & venting
Hydrophobic PTFE configurations can be used for air, gas and vessel
vent applications where liquid water penetration should be resisted.
Prefiltration
Polypropylene and larger-pore membrane configurations can remove
particulate loading before a finer downstream membrane stage.
Laboratory filtration
Compact capsules provide a convenient format for sample preparation,
method development, compatibility trials and small-volume filtration.
Pilot & single-use systems
Capsule formats reduce the need for reusable housings and can simplify
temporary, pilot and single-use process assemblies.
Quality, Integrity Testing & Material Compliance
Depending on the selected capsule family and configuration, technical
documentation is available for material safety, integrity testing,
sanitisation and operating limits. Requirements should always be confirmed
against the exact filter grade selected for the process.
100% integrity testing
Selected capsule ranges are individually integrity tested as part of
manufacturing quality control.
USP Class VI
Selected capsule materials meet biological-safety specifications for
USP Class VI plastics.
Autoclave compatibility
Selected compact configurations support autoclaving at 121 °C for
30 minutes and repeated cycles.
Material compliance
Selected constructions have documented FDA 21 CFR and EU 10/2011
food-contact material compliance.
Pharmaceutical note: integrity testing, USP Class VI material
compliance and a 0.2 µm pore size do not by themselves establish that every
capsule configuration is a validated sterilizing-grade filter. Ask for the
validation documentation applicable to the exact membrane grade and
configuration required.
Capsule Filter Connections and Configuration
Capsule filters can be supplied with different connection styles depending
on capsule family and process requirements. Available configurations across
the range can include Tri-Clamp, NPT, hose-barb, quick-connect and
instrumentation-style connections.
Connection type should be selected together with membrane material, pore
size, required filtration area, process volume and operating conditions.
Compact laboratory capsules and larger process capsules can have different
filtration areas and dimensional specifications even when they use the
same membrane material.
How to Select a Capsule Filter
For reliable sizing, provide the process fluid, membrane preference,
required pore size, batch volume or flow rate, operating pressure,
temperature and connection requirements.
| 1. Process fluid |
Water-based liquid, protein solution, solvent, chemical, air or gas |
| 2. Filtration objective |
Clarification, prefiltration, fine filtration, bioburden reduction, gas or vent filtration |
| 3. Membrane |
PES, PTFE, PVDF, Nylon or Polypropylene |
| 4. Pore size |
Select according to the required retention level and process validation requirements |
| 5. Process volume |
Laboratory sample, batch, pilot-scale or larger process volume |
| 6. Connections |
Confirm required inlet/outlet fitting and sanitary or tubing interface |
| 7. Operating conditions |
Pressure, temperature, chemical compatibility and sterilisation method |
| 8. Documentation |
Confirm integrity testing, biological safety and validation requirements where applicable |
Need Help Selecting a Capsule Filter?
Send us your liquid or gas, required pore size, process volume, pressure,
temperature and connection requirements. We can help compare PES, PTFE,
PVDF, Nylon and PP capsule configurations for your filtration process.
Capsule Filter FAQ
What is a capsule filter?
A capsule filter is a self-contained filtration device in which the filter
membrane or filter media is permanently enclosed inside a disposable housing.
It can be installed directly into laboratory, pilot or process tubing without
using a separate cartridge-filter housing.
Which capsule filter membrane should I choose?
PES is commonly selected for aqueous liquids, PTFE for hydrophobic gas,
venting and compatible solvent applications, PVDF for low-protein-adsorption
liquid filtration, Nylon for aqueous and compatible alcohol-containing
solutions, and polypropylene for particle prefiltration.
What is the difference between PES and PTFE capsule filters?
PES is hydrophilic and is normally easier to wet with aqueous liquids.
PTFE is hydrophobic and is commonly selected for gas, vent and compatible
solvent filtration. Chemical compatibility and process requirements should
always be checked before selection.
Are 0.2 micron capsule filters available?
Yes. 0.2 µm configurations are available in several membrane families.
However, a 0.2 µm pore size alone does not automatically demonstrate
validated sterilizing-grade performance.
Can capsule filters be used in pharmaceutical applications?
Yes. Capsule filters are used in pharmaceutical development, pilot filtration,
single-use systems, buffer and process-liquid filtration, and gas or vent
applications. For regulated sterile processes, the exact filter grade and
supporting validation documentation must meet the application requirements.
Can capsule filters be integrity tested?
Selected capsule filter ranges are 100% integrity tested during manufacturing,
and some configurations support additional integrity verification. The
applicable test method and acceptance limits depend on the membrane,
pore size and filter grade.
Are capsule filters autoclavable?
Selected capsule configurations support autoclaving. For the documented
compact capsule range, autoclaving at 121 °C for 30 minutes over multiple
cycles is specified. Always verify the limit for the exact capsule configuration.
