This question is not so easy to answer. There is no general rule or regulation on how often filters need to be changed in a Cleanroomneed to be changed in a company. Our filters usually run for several years without needing to be changed. However, the service life varies considerably depending on the application.
As a general rule, the more particle-laden the air drawn in (either outside air or the process at Cleanroom), the faster a filter becomes clogged. In a high-emission hall and a direct hall intake of the FFU, the filters therefore clog faster than in a closed system in which the already filtered air is filtered again and again in a recirculation circuit. In cleanroom production with high particle emissions, the filter becomes clogged more quickly than in pure inspection work, for example.
So you can’t say for sure. We have a customer who has been using original filters in his Cleanroom for over 20 years without any loss of performance. But that is admittedly rather unusual.
If a filter becomes clogged with particles over time, its volume flow decreases. It is therefore important to check the condition of the filter regularly and replace it before its performance deteriorates too much. This has an effect on the air exchange rates and differential pressures in the room. If a filter fan unit does not have a clogging indicator, the performance is checked at the latest during regular maintenance or air velocity measurement. The individual filters are identified and replaced if necessary. As the filters become clogged slowly, slight corrections to the fan speed of the FFU during maintenance can also indicate that the filter change will be due in the coming year and can therefore be planned.
If you also need to keep an eye on microorganisms for the manufacture of your products, the permitted period of filter service life should be considered by means of a risk assessment, in which contamination by microorganisms must also be prevented. There is a risk that airborne microorganisms could get trapped in the filter and multiply there under unfavorable circumstances. In the worst case, germs could break through via the filter side. There are no regulations here either, but it is advisable to routinely replace the filters every 3-5 years or to continuously test the airborne microorganisms and monitor the trends.
Ultimately, it is the responsibility of the cleanroom operator to develop a maintenance program that ensures filters are changed in a timely manner to maintain the cleanliness of the environment.
