Liquid sterilizing filtration
Review pre-use and post-use test conditions for hydrophilic membranes and capsules.
Biopharma · APPLICATION GUIDE
Filter Integrity Testing
Review filter integrity testers for sterile filtration, PUPSIT and gas or vent filters. Match supported methods, connections and records to filter-specific validated criteria.
Review selection pointsDiscuss this applicationTEST APPLICATIONS
Which filters will be tested?
Gas and vent filtration
Confirm test methods for hydrophobic filters, and housing, condensation and sterilization conditions.
PUPSIT configuration
Review connections, exhaust, recovery and records for pre-use post-sterilization testing.
FIELD APPLICATION & FLOW
See the application in its industrial setting.
Review product locations and fluid paths.
APPLICATION IN CONTEXT
- Test-gas supply
- Automated integrity tester
- Filter under test
- Downstream boundary/exhaust
- Test record
Connections to review
- 01 → 02 Test-gas supply → Automated integrity tester
- 02 → 03 Automated integrity tester → Filter under test
- 03 → 04 Method-specific downstream path
- 02 → 05 Automated integrity tester → Test record
Diffusion, bubble point, pressure hold and water intrusion use different setups and principles. Apply the validated filter-specific method. Review the method-specific connections and principles below for bubble point, pressure hold and water intrusion.
A conceptual illustration created to explain equipment and application locations. It is not an actual product photograph, installation photograph or piping/wiring design.
Connection principles and operating/test methods
Diffusion flow · defined differential pressure
GasMeasurement / control
Scroll horizontally to see the complete flow.
Evaluate gas diffusion through a wetted membrane at a validated differential pressure below its bubble point. Depending on the instrument, flow is measured directly or calculated from upstream volume and pressure change. Confirm filter-specific fluid, gas, temperature, area, limits and the downstream boundary.
Bubble point · pressure rise and flow change
GasMeasurement / control
Scroll horizontally to see the complete flow.
Increase upstream pressure on the wetted filter and evaluate the change in gas flow as wetting liquid is displaced from the largest pores. Detection depends on the instrument and filter. Confirm the validated fluid, temperature, pressure range and minimum acceptance criterion.
Pressure hold / decay · isolated upstream
GasMeasurement / control
Scroll horizontally to see the complete flow.
After pressurization and stabilization, isolate the gas supply and evaluate upstream pressure change over time. Upstream volume, filter diffusion, system leakage and temperature affect the result. Follow validated limits, measurement time and sterile-boundary controls.
Water intrusion · hydrophobic filter upstream
GasFluidMeasurement / control
Scroll horizontally to see the complete flow.
Cover the upstream side of an applicable hydrophobic filter with validated water and evaluate the measurement associated with water intrusion or water transfer at the defined pressure. Confirm instrument measurement/calculation and filter, housing, volume and temperature limits. The view does not represent bulk water being forced through the membrane.
These conceptual views explain flow direction. Actual piping, wiring and physical flow rates require a separate design.
01 — PROCESS
Where does each step fit?
Define the intended use and conditions to identify the required role of each item.
Filter and test preparation
Confirm the test object, whether the membrane is hydrophilic or hydrophobic, test fluid and gas, and sterilization history.
Connection and automated testing
Connect, wet and stabilize according to the approved procedure, then measure using the program for the relevant filter.
Assessment and records
Check acceptance limits, raw data, filter and batch identification, and operating history; investigate failures using the defined procedure.
02 — SELECTION
Which integrity-test method applies?
Automated integrity testers measure changes in gas flow or pressure and compare them with the validated criteria for the relevant filter. Review equipment according to filter type, test method, connection configuration and record requirements.
Scroll horizontally to review all columns.
| Test method | English designation | Principle and conditions |
|---|---|---|
| Diffusion flow test | Diffusion / Forward Flow | Measure gas flow when a specified differential pressure is applied to a wetted filter. Confirm the test fluid, area, gas, temperature and acceptance limit for the relevant filter. |
| Bubble point test | Bubble Point | Detect the pressure at which wetting fluid is displaced from the membrane’s larger pores and gas flow increases. Confirm the wetting condition and validated method for each filter. |
| Pressure hold or decay test | Pressure Hold / Decay | Evaluate pressure changes in the sealed upstream side. Confirm upstream volume, system leakage, temperature and the filter-specific correlation criteria. |
| Water intrusion test | Water Intrusion Test · WIT | Use water to test suitable hydrophobic gas or vent filters. Confirm the filter, area, housing and scope of applicability of the validated method. |
Use acceptance limits validated for the specific filter, test fluid, gas, temperature, area and actual configuration. Instruments differ in supported methods and features.
03 — OPERATING CHECKS
Confirm these points before selection.
Match test functions and operating range
Confirm the required test methods, filter area and number of filters, test volume, pressure and flow ranges, and measurement performance. Not every instrument supports every test method.
Review the process connections together
Check test-gas quality, filter connections, protection against liquid backflow and exhaust paths. PUPSIT requires a configuration that maintains the sterile boundary during post-sterilization testing.
Define records and maintenance
Define requirements for user permissions, audit trails, electronic signatures and result export. Review calibration, IQ/OQ and system qualification documentation.
04 — QUESTIONS
Frequently asked questions
Does a passing result guarantee product sterility?
The test evaluates filter and assembly condition under validated conditions. It does not replace validation of microbial retention, hygiene and sterility controls across the entire process, or product quality evaluation.
Should the filter be replaced immediately after a failed test?
Insufficient wetting, connection leaks, temperature changes and incorrect settings can also cause failure. Preserve the initial result and make the decision according to approved investigation and retest procedures.
Can this instrument also perform single-use bag leak tests?
Filter-test functions alone do not establish the ability to test bags for leakage. Separate supported functions, accessories, a validated method and the bag’s pressure limits are required.
Can existing filter test settings be copied to a new tester?
Use existing settings as comparison data, then confirm supported methods, units, measurement ranges and connections. Establish the validated criteria for the filter, area, test fluid, gas and temperature, together with the approved procedure and equipment qualification scope, before configuring the test program.
05 — APPLICATION REVIEW
Prepare the conditions for a technical discussion.
Share the current configuration and operating conditions to review selection criteria and required evidence. Suitability and supply scope are confirmed for each application.
- Filter and housing identity; membrane type, area, quantity and connections
- Required test methods and validated limits; test fluid, gas and temperature
- Sterilization and test timing; PUPSIT connection drawing and sterile boundary
- User access, audit trail, electronic signature, export and integration requirements
- Installation environment, calibration, IQ/OQ or other documents and evaluation timing
Review your filtration requirements
Selection, replacement or quantity and lead-time review. Start with the information you have.