Yesterday into today, I've been shopping for laminar flow HEPA fan filter modules for the PSOMA optical enclosure. I didn't find a lot of LIGO documentation listing specific filters, but here's what I've found online with some downselection on 'low vibration / high filter quality'. Please let me know If there's a company we often use, or if you can help direct this search at all.
Another consideration is flow rate relative to our volume. I can do this calculation, but what is the particle density (eg at 0.3 um) we want to achieve inside the enclosure? I realize that I never got the particle counter recording despite it being on my list, so I'll try to do that remotely today. We need to know the ambient particle count and the clean volume in the enclosure.
*all prices listed here are from publicly available pages