Improved N95 CPR Pocket Face Mask Using External Canister
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- Filter media not secured to canister yet. Top of bottle sealed to plastic bag with elastic band.
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- Holes drilled into bottom of pill bottle using common cordless drill.
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- Resealable plastic bag used as air conduit between exhaust port and pill bottle canister. Exhaust port turned towards top of pill bottle.
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- Excess plastic bag material inside the mask should be trimmed away.
This is an improvement on my N95 Mask Using CPR Pocket Face Mask and Air Purifier HEPA Filter design. Compared to that design:
- Breathability is greatly improved by increasing the surface area of the airflow through the filter medium. With a larger diameter canister (pill bottle), lower efficiency filter media (higher resistance to breathing) can be used as surface area for airflow is increased.
- The filter medium is not as subject to deformation that could reduce performance or release potentially hazardous reinforcement material (e.g. fibreglass).
- Construction still requires minimal skill and basic tools (a hot nail could be used in place of a drill), though assembly is less straight-forward. Decontamination will be more difficult.
Parts:
- CPR Pocket Face Mask
- Pill bottle
- Plastic sandwich bag
- Elastic bands
- Filter media. This could be of any material available, from better than nothing to excellent. In this example, the patch of filter media was harvested from a True HEPA filter unit for a home air purifier. WARNING: This filter media probably contains fibreglass, which is something you do not want to inhale. Hot gluing the edges of the patch and sandwiching the patch between two layers of cloth might help. But I am playing it safe and moving on to other materials that are guaranteed to be non-hazardous.
Tools:
- Scissors
- Drill or hot nail
Future work:
- Larger canister to support use of double layer of tea towel, which has terrible resistance to breathing, but apparently pretty good filtration performance.
- See follow-up post: Efficacy of Double Layer of Tea Towel as Filter Medium
- Salt functionalized filter element inside or outside canister.