In the upcoming period we will upload a series of 3 blogs in which we will learn you more about filter integrity testing. 
In these series:
- Water Intrusion Test (WIT)
- Bubble Point Test (BPT)
- Diffusion Test (DFT)(Forward flow test)

As filter products are widely used by a number of industries to achieve required levels of purity in liquids and gases, verification of filter performance has become an important issue in several industries. This has led to the development of Integrity testing of filters.
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We conduct Integrity testing of various media filters using different Test methods via a range of automated integrity testers which offers non-destructive methods for proving the capability of a filter product to meet its stated performance when it is installed in an application.

WATER INTRUSION TEST (WIT)

The Water Intrusion Test (WIT) measures the volumetric flow rate of water that intrudes into a hydrophobic media /membrane of the cartridge at an applied pressure per 10 minutes. It is a highly sensitive, integrity test only for hydrophobic sterile air filters, which is carried out without the use of solvents such as Iso-propanol. The pores of hydrophobic filters will resist the passage of water up to a certain pressure.
The pressure at which water will pass through the pores of a hydrophobic filter is inversely proportional to the size of the pore. The Hardware Volume is a parameter of a water intrusion test program. It is the volume between the top end of the filter membrane and the pressure sensor situated at the top end of the housing.

Merits
- Only water required as the test liquid.
- No alcohol needed.
- No need to handle flammable liquid.
- Contaminants such as solvent mixtures are avoided.
- The test can be performed in place after steam sterilization.
- Filter is not wetted ready for use immediately after testing.
- No time – consuming for wetting procedure.
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Demerits
- This test is very sensitive test, if there is a change in average pore size of membrane - The WIT value may differ.
- Temperature of water should be at room temperature.It can be used only with difficulty as an in situ test.
- Solvent residue can contaminate the filtrate side and create hydrophilic areas.
- The drying procedure is time consuming.
- Any contaminant, creating hydrophilic areas, will not be detected.
- Specific test areas and equipment is required due to solvent vapour.

We provide Water Intrusion Test for all hydrophobic filters cartridges and capsule filters. Such as Pall, Sartorius, Merck Millipore, Parker/ Domnick Hunter, 3M/ Cuno, Amazon etc.

In the upcoming blogs:
Abstract of integrity tests 2/3 – Bubble Point Test (BPT)
Abstract of integrity tests 3/3 – Diffusion Test (DFT) (Forward flow test)