I am facing problem in filter integrity during sterilization with fermenter. Every time after sterilization, integrity test of filter has failed. I am using PTFE membrane filter which are polypropylene and hydrophobic and the pore size is 0.2 micron. Those are air filter using for sterile air in fermenter. During sterilization, the filter has reached 121 degree temp and 1.5 bar pressure.
When I checked new filter without sterilization, it has passed. So there is no question about integrity machine and sterility of fermenter media has also passed. So there is also no question about sterilization process.
What are the main reason for integrity fail?
Thanks & Regards
Dipak Das
Hi Dipak
Does "integrity test" mean you estimated the average porousity by bubbling point control? Have you ever thougth to use a hydrophilic membrane?
PTFE mebranes are sensitiv to moisture, also the overall trespassing volume of gas is low, usually you use regular deepfilters for gas-inlet filtration. I had problems with PTFE on Sixfors-Mini Fermentors and god rid after changing to a hydrophilic membrane type
If you want to use your filters, we could try to equilibrate the pressure on the filters by slightly opening a reactor plate inport without compromissing the sterility. you can even close the filters, so no moisture from the reactor to go on them. The cooling should take place slowly.
I could be associated with differential pressure. There may be a malfunction of the steam trap during the filter sterilization process in the fermenter and this causes a pressure drop that is capable of piercing the mambrana. This type of membrane may fail under mechanical stress.
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