Patent ID: 6983504

Claim:
A method for testing the integrity of at least one filter element arranged in a device, said method comprising: (a) filling pores of the filter material of the at least one filter element in the device with a wetting liquid, (b) purging at least the retentate side of the at least one filter element in the device with a first gas, (c) pressurizing the at least one filter element with the first gas under a test pressure and at a test temperature, (d) measuring the volumetric flow rate of the first gas through the at least one filter element at the test pressure, (e) degassing the device, (f) repeating steps (b) to (d) with a second gas, (g) determining the ratio of the volumetric gas flow rates, (h) determining the ratio of the solubility or diffusion coefficients of the gases in the wetting liquid at the test temperature, and (i) determining a convective component of the volumetric gas flow rate, wherein the ratio of the solubility or diffusion coefficients of the first and second gases in the wetting liquid at the test temperature is at least 1.25:1 and the viscosities of the gases at the test temperature do not differ by more than 50%.