I disassembled one of the two HEPA filter of the cleanbooth for the absorption measurement system ( Model MAC-103 ) in order to check the conditions and to figure out whether and how to change it. The circular prefilter is very easy to replace and very dirty, I think we should change it. The real HEPA filter inside is quite dirty but is not easy to replace because the filter is kind of glued at the frame, so maybe we can contact the company. I hope there is the possibility to change only the filter, and not the whole fan.
The filter's fan part was fine, so it was enough to buy only the filter part. New HEPA filters were delivered to Tama last friday. I washed the prefilters with water, I cleaned the fans, replaced the filters and placed them back to the top of the absorption bench clean booth.