Covid Mask from Snorkel Facemask

thingiverse

Includes designs for simple adapters to allow air filters on both air inlets and optionally on the outlet of a "HJKB Full Face Snorkel Mask with double tubes". This mask uses unidirectional air flow - 2 inlets are located at the back, and air is exhaled through a one-way valve in the front of the mask. Adapters accept press-in filter grids as used in the Billings Montana mask. Multiple separated filter layers can be added to the inlets, and a bag around the inlets serves as a pre-filter that's easily swappable without removing the mask. For filter squares, look up recommendations for the Billings mask since guidelines are still evolving. A filter on the front one-way outlet valve is optional when only the mask wearer needs protection from surroundings. Many N95s also have similar one-way outlet valves. However, if nearby people need protection from the mask wearer, install the outlet filter adapter. The safety and efficacy of this modified mask design haven't been tested in clinical or nonclinical settings. Sterilization techniques specific to this mask haven't been studied. Improvised filter materials vary in effectiveness. Use at your own risk, as approved equipment is still available. This design is specific to the HJKB Full Face Snorkel Mask with double tubes and won't work on most other snorkel masks since they use a single-tube design. The HJKB mask is still available for fast delivery on Amazon as of 4/13/2020. Other masks may be adapted using: https://www.thingiverse.com/thing:4266047. Instructions are as follows: Print (2) filter shaped objects without support and 4 Billings grids. If outflow filtering is desired, print the other cylindrical part and at least one more grid. Supports may be needed for this second part. Use PETG(preferred) or PLA. Other materials may be less safe. Unpack the snorkel mask but don't attach the tubes. Instead insert a funnel adapter into each inlet. Filter squares can be pressed into the square hole in the top of the funnel using Billings grids. The design allows for 2 grids if multiple separated filter layers are desired. Funnel tubed fit tightly but can be further secured to the mask body using the attachment point provided on the funnel. An optional prefilter can be made by wrapping blue shop towels or other filter material around the outside of the funnel as shown in one of the pictures. This can be quickly changed without removing the mask, and may deter splashes from reaching the inner filter material. If the outlet filter is desired, press the piece over the large front outlet valve of the snorkel mask and add a filter square. It fits tightly but securing it with tape or epoxy putty might be prudent to prevent air leaks or inadvertent dislodging. There's also a second lower outlet valve on the chin of the scuba mask that should be sealed airtight with tape or other material. Disclaimer: Improvised devices are not NIOSH-approved. The user bears all liability associated with using such devices, this device in particular. I'm making this information available as a public service but don't make any warranty, expressed or implied, that the use of this device is safe or will protect against COVID-19 or other airborne viruses.