In order to ensure the consistent integrity of a cleanroom, so-called filter integrity tests have to be performed for all filter elements of a cleanroom at regular intervals in the pharmaceutical industry. This helps to detect and eliminate leaks at an early stage in order to maintain the protective function of a cleanroom.

Current practice in the cleanroom environment

Currently, filter integrity tests are carried out manually. This means that a certifier guides a telescopic rod, with a measuring probe attached to the end, in meandering paths over the filter units to be tested. Particles are applied upstream of the filter element using a challenge aerosol and downstream the whole filter face is scanned with a probe. The particle counter measures the particle quantity below the filter unit.

Challenges of the manual filter integrity test procedure

In order to obtain correct filter integrity test results, the applicable standards require a constant probe velocity while maintaining a constant distance between the probe and filter surface area throughout the entire measurement. These aforementioned requirements can neither be tracked nor documented using manual measurement methods. Therefore, the obtained results are subject to inaccuracies due to the above mentioned factors and rely heavily on the training status and experience of the individual certifier. The manual filter integrity test procedure is still worldwide industry standard, despite its well-known drawbacks. Apart from the constant probe movement requirements, it is difficult to prove and document the scanning of the entire filter surface without gaps in a given timeframe according to the standards and regulations.

Our solution

Smart Cleanroom Solutions GmbH has addressed this issue and developed the first automated solution for testing the integrity of filter elements, such as those used in filter fan units (FFUs) or terminal S-filters. The product family AutomaticParticleScanSystems (APSS) currently consists of the three robotic systems RobotScanFlex (RSF), integratedRobotScanFlex (iRSF), and LinearTwinScan (LTS), which automate the localization of leaks and probe guidance. These robots offer mobile solutions that provide significantly higher measurement accuracy, guarantee controlled scans, generate reproducible results in real time, and minimize the time required for documentation.

Our mobile robotic solutions for filter integrity testing are characterized by their significantly higher measuring accuracy, which is guaranteed by high precision with which the SCARA robotic arm scans the entire filter element in a meandering pattern.

Choosing an automated alternative from our APSS family increases process reliability and achieves more reliable measurements. The distance of the probe to the filters surface as well as the movement velocity of the robotic arm and the linear rail remains constant during the measurement process. The scanning speed can be preset by the user before the test and is documented in the report.

The overlap of the meandering paths required by the standards can be maintained exactly. The adjustable probe height allows the system to be adapted to the spatial conditions in order to avoid any obstacles below the filter element.

Because of the accurate motion of the robotic systems, each area of the filter is correctly scanned without gaps- thus recognizing potential leakages reliably. The fully automatic process reduces the requirement for intervention or interaction by the certifier to an absolute minimum.

The use of robotic systems delivers reproducible filter integrity test results. During a measurement, a 2D heatmap is drawn in real-time and visualized on the tablet screen. This provides the users with necessary details about the measurement process and indicates where potential leakages are located on the filter surface. Furthermore, it is possible to preset and monitor the upstream particle challenge concentration during the entire measurement period, which is automatically adjusted to the required value in the event of deviations.

With our robot-guided scanning method, we are able to visualize the quality of the filters. This type of visualization allows particularly meaningful conclusions to be drawn with regard to the filter quality and the correct sealing surrounding the filter. Critical points are automatically checked and evaluated.

By using the in-house developed APSS software packages, the measurement reports of the filter integrity tests are digitized and available electronically for long-term storage. A GMP Annex 11 and 21 CFR Part 11 compliant report with all required data can be generated onsite in just a few minutes after completing a filter integrity measurement.

The efficient production processes in which our robots digitize important process steps eliminate the need for paper based workflows. During the preparation as well as the post-processing of a measurement, all required data is electronically recorded, processed, and stored.

In summary, this innovative process takes filter integrity testing to a new level. This is also demonstrated by the recently revised DIN EN ISO 14644-3 standard, in which automated filter integrity tests are added for the first time by the International Organization for Standardization (ISO).

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