CV-19 Guardian Respirator Adaptor

Last crawled date: 1 year, 10 months ago

In response to shortages in NIOSH-approved PPE during the COVID-19 crisis, many individuals including healthcare professionals and first responders are turning to improvised masks for protection. To help provide for more controlled protection under these circumstances, Dominion Engineering, Inc. (DEI) has developed a custom adaptor that, along with commonly available materials, can be used to convert a standard snorkel mask into a reusable, full face respirator that effectively protects the eyes, nose and mouth from airborne particles. We have coordinated independent testing to confirm that these converted masks pass a standard mask fit test and to assess the efficacy of commonly available filter insert materials.

To assist individuals who may lack access to approved PPE such as N95 respirators and face shields, DEI is publishing the CV-19 Guardian Respirator Adaptor design here, along with instructions for making a converted mask using this adaptor. For additional technical information, including filter efficacy testing results for commonly available materials that can be used to make filter inserts for this adaptor, refer to the attached PDF file.

Disclaimer: Improvised devices of the type discussed herein are not NIOSH-approved and the user bears all liability associated with the use of such devices. DEI is making this information available as a public service, but does not make any warranty, expressed or implied, that the use of the device described herein will protect a party from COVID-19 or any other airborne viruses.


To assemble a converted respirator mask, you will need the following:
1 - 3D printed adaptor (design file attached)
2 - Compatible snorkel mask
3 - Filter insert material
4 - Wide mouth lid (mason jar, or equivalent)

Snorkel Mask: The CV-19 Guardian Respiratory Adaptor is designed to fit the DIVELUX snorkel mask (https://www.amazon.com/dp/B072KDWVSV/ref=cm_sw_em_r_mt_dp_U_PJ5FEbJPZE8VG). Many other commonly available snorkel masks utilize similar construction. DEI will continue to evaluate the compatibility of other masks with the CV-19 Guardian Respirator Adaptor and publish additional compatibility information as it becomes available.


Filter Insert: Once the CV-19 Guardian Respirator Adaptor is inserted into the compatible snorkel mask, a filter insert cut from a commonly available material that effectively captures airborne particles is placed on the sealing surface of the adaptor and secured in place using a compatible lid. The attached PDF file provides instructions for properly making and using filter inserts, along with URL links for commonly available materials that provide effective protection against airborne particles. One example material with good breathability and >99% filtration efficiency of airborne particles of interest is two layers of ADO Pro Pac fabric, which is commonly used to capture particulate from blown insulation (https://www.homedepot.com/p/ADO-Products-10-2-ft-x-375-ft-Pro-Pac-Insulation-Fabric-ICPP122/302709283).

As configured, most standard snorkel masks such as the DIVELUX mask allow the wearer breathe filtered air in through the CV-19 Guardian Respirator and filter insert, and exhale unfiltered air through a vent valve in the front of the mask. This is equivalent to an N95 mask with an exhaust valve, which protects only the person wearing the mask, but not those in close proximity from any airborne particles expelled by the wearer. Most full face coverage respirator masks utilize this type of construction because it is easier to breathe and prevents mask fogging and filter deterioration due to moisture. However, if it is desirable for the mask to function in a similar manner to an N95 max without an exhaust valve, the vent valve in the snorkel mask can be effectively blocked by taping over it on the interior of the mask. This makes it more difficult for the wearer to breathe through the mask, but ensures both inhaled and exhaled air are filtered (protecting both the wearer from surrounding airborne particles, as well as those in close proximity from any airborne particles expelled by the wearer).


Wide Mouth Lid: For maximum compatibility and ease of use for the general public, the diameter and threading of the CV-19 Guardian Respirator Adaptor is the same as that of a wide mouth mason jar. Any standard wide mouth mason jar lid ring (for canning) will fit the adaptor and function as intended (see photos). Compatible lids with sprouting or straining inserts provide good structural protection for the filter insert. One example lid of this type is the
Original Speed Strainer Lid® (wide mouth size), https://www.unboundfarm.com/The-Original-Speed-Strainer-Lid®_p_12.html.

It is not recommended to cut a hole in a single-piece mason jar lid as the sharp edges could damage and compromise the integrity the filter insert.


Details: For additional technical details, refer to the attached photos and PDF file.


3D Print settings: Printer used for prototyping: Prusa Mk3, Rafts: No, Supports: None, Resolution: 0.2 mm, Infill: 20%, Filament - Hatchbox PLA, White

PTEG or PLA are suitable. In absence of these, other materials should be acceptable as well. ABS tends to shrink after production; a prototype made from this works acceptably, but the shrinkage could result in an inferior seal at the interface or require adjustment. PTEG is chemically resistant, so it may be a good candidate if masks will be chemically decontaminated.

Multi-Jet Fusion (MJF) is expected to be an ideal process for commercial production of this part due to the durability of the resulting parts and demonstrated ability to withstand autoclave disinfection.