Palltronic® Flowstar IV Filter Integrity Test InstrumentSource: Pall Life Sciences - BioPharmaceuticals
With the Water Intrusion Test (WIT) fast becoming the in situ integrity test of choice for hydrophobic filters, the Palltronic AquaWIT IV system is the latest in the line of Pall’s state-ofthe- art products developed specifically to perform crucial filter integrity testing - accurately, reproducibly and reliably. The system fills the housing of a hydrophobic filter with water, performs a Water Intrusion Test, then drains the housing. A new feature to this latest version of the Palltronic AquaWIT system is the option to wet hydrophilic liquid filters with water prior to integrity testing by the Forward Flow or Bubble Point test. A clear and well-defined wetting procedure that uses minimal water can be of real benefit for the pre-use testing of filters, for example in Allegro™ single-use systems.
A detailed description of the physical basics of water intrusion testing can be found in PDA Technical Report 40 Sterilizing Filtration of Gases or at www.pall.com/wit. In summary, a hydrophobic membrane is completely covered with water and air pressure is applied to the water. The water will evaporate through the hydrophobic membrane, and the rate of water evaporation (vapor flow) can be measured indirectly. The apparent water/vapor flow rate is correlated to bacterial retention tests carried out on the hydrophobic filter.