(Failed) Attempt to adapt a HEPA vacuum cleaner filter

A project log for Ocean Reef Snorkel Face Mask, Emergency PPE

Converting an Ocean Reef Snorkel Mark into emergency PPE.

Lex KravitzLex Kravitz 04/14/2020 at 19:520 Comments
Our first attempt to adapt a filter to the Ocean Reef mask was to use a HEPA filter from a vacuum cleaner.  This was attractive as these filters are cheap, widely available, and supply does not appear limited at the moment.  We modified the adapter provided by the Ocean Reef group, more info on that adapter can be found here.

We provide our design notes below for the benefit of documentation, but unfortunately we were not able to achieve adequate filtration with this approach.  We believe the issue may have been the leaks between the walls of the filter and our adapter, although it is hard to be certain.

Photos of filter:

First design (printed in eRigidForm resin on EnvisionONE printer)

Non-quantitative N95 quality testing (it passed this "smell" test)

2nd smaller design:

This design was tested at Washington University in St Louis and unfortunately it failed to achieve the filtration level of a P95 mask.  We abandoned this approach at this point and moved to testing 3M P100 filters (below).  That said, there are supply issues with obtaining the 3M filters at the moment so we may revisit this design in the future.