Automated In-Situ Leak Testing and Filter Integrity Testing, Allegro™ Connect Virus Filtration System

Posted on May 19, 2023

Nigel Jackson, Principal R&D Engineer, Pall Corporation

Summary
This application note highlights the capabilities of the Allegro Connect Virus Filtration System to accurately and consistently conduct fully automated in-situ manifold leak testing and filter integrity testing.

Introduction
The Allegro Connect Virus Filtration System is a single-use automated filtration system designed to deliver robust process control and integrity assurance during this critical purification step.
This next generation compact system is designed to minimize risk through a fully automated process with recipe-controlled steps. These include pre-use manifold leak testing, pre-use and post-use filter integrity testing (utilizing an integrated Palltronic® Flowstar IV Integrity Test Instrument), system priming, product filtration and buffer chase, with all data stored in a batch reporting system. This system improves process control by significantly reducing non-conformities and manual labor.
New innovative design features allow manifold configurability to meet a variety of process needs, supporting a wide range of liquid filter capsules (prefilters and virus filters) while also accommodating filters from alternative manufacturers.

Materials and methods
All manifolds were installed and operated on the system in accordance with the instructions for use (Pall reference document USD 3834).

System and manifolds
All manifold sets selected incorporate four prefilters and two virus filters. This configuration would not normally be used with filters smaller than 508 mm (20 in.), with more compact options available. The choice was made to demonstrate the integrity of the most complex manifold and show the ability to separately integrity test two virus filters in series.

Leak test
The manifolds detailed in Table 1 were installed as per the guided instructions in the standard installation phase on the system. Once installation was complete, the recipe continued to an automated manifold leak test phase. Prior to water or product commitment, the Allegro Connect Virus Filtration System activated the leak test function on the Palltronic Flowstar IV Integrity Test Instrument at 1200 mbar manifold pressure for 10 minutes. The test is capable of measuring flow rates between 0.1 – 1000 mL/min using volume-dosed flow measurement technology.

Forward flow integrity test
Before pre-use filter integrity testing, automated standard preparation phases were carried out to prime and flush the system and filters. All phases complied with the specific slow filling of water and flushing at the required backpressure as per the instructions for use for the Pegasus Prime Virus Removal Filter (Pall reference document USD 3132).
After full filter processing, the standard buffer chase phase carried out a water flush to prepare the system for post-use integrity testing.
Both integrity tests were carried out in series using the same standard recipe phase. The Allegro Connect Virus Filtration System activated the forward flow integrity test function of the Palltronic Flowstar IV Integrity Test Instrument at 4150 mbar and 10 minutes for each filter in series, to generate individual integrity test results for each virus filter installed.

Results
Manifold leak test
The built in Palltronic Flowstar IV Integrity Test Instrument allows manifold leak testing on the system as part of a fully automated process, without any need for a separate integrity test instrument skid or any manual connections post installation.
Following installation, the manifold leak test is carried out dry to assure a leak-free process before any product is committed to the process, or any of the flow path is wetted with water. The status and results of the leak test are displayed on the human machine interface (HMI) screen as the test progresses. An example data set is displayed in Figure 2, demonstrating the highly accurate pressure control and typical decrease in flow rate before stabilization towards the end of the test. The pass result confirms the leak free status of the installed manifold.

Filter integrity test
An automated filter integrity test is carried out to ensure the integrity of the virus filters and the virus retention performance at point of use. This is undertaken after priming and flushing the filters (pre-use) and after the processing, buffer flush and water flush (post-use). The progress is again monitored on the HMI screen during the test. Each of the two virus filter positions can be integrity tested in parallel, or each in series one after another.
A summary of filter integrity test results generated in series both pre-use and post-use with 254 mm (10 in.) Kleenpak™ Nova capsules with Pegasus Prime virus removal filter membrane, is shown in Figure 3. The pass results not only confirm the virus retention integrity of the filters tested, but also the consistent success of the fully automated slow fill priming and fully automated filter flushing (with back pressure) required to effectively wet the virus filters.

Conclusions
The Allegro Connect Virus Filtration System facilitates fully automated in-situ manifold leak testing and filter integrity testing with the integrated Palltronic Flowstar IV Integrity Test Instrument.
Results show this system to be effective for leak testing before water or product commitment to assure a leak free process.
Results also show that automated filter priming and wetting combined with automated in-situ filter integrity testing secures consistent and successful measurement of filter integrity, ensuring virus removal performance at point of use.

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The information provided in this literature was reviewed for accuracy at the time of publication. Product data may be subject to change without notice. For current information consult your local Pall distributor or contact Pall directly.

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