The Water Intrusion Test is a practical and validated test which can be used for in-situ integrity testing of hydrophobic gas filters. This test is conducted with deionized or higher quality water, without the need for low-surface-tension flammable solvents (such as Isopropyl Alcohol or Ethanol). Due to occupational risks, environmental regulations, safety guidelines and cost associated with handling these low surface tension solvents, water intrusion is becoming the method of choice for integrity testing hydrophobic microbial rated filters for air or gas applications.

Water Intrusion testing is the preferred test where the hydrophobic microbial rated gas filter:

  • Is integrity tested in-situ
  • A pre-use test is performed (especially after sterilization)
  • Alcohol use is restricted or not allowed in the production area

The Forward Flow or Bubble Point test, is the preferred method to integrity test filters in applications where:

  • A small area filter is used
  • An off-line filter integrity test is performed
  • To confirm filter integrity following a water intrusion test failure evaluation

For more information, please see Pall Publication, USD 3033 Application Note: Best Practices for Successful Filter Integrity Testing Using the Water Intrusion Test (WIT) Method