large_preview_MSA_BAYONET_TO_3M_BAYONET_

MSA® Bayonet to 3M™ Bayonet Filter Adapter

A prototype assembly for MSA® to 3M™ bayonet-bayonet adapter, originally requested by macelius. Designed to help cross compatibility of COTS filters with other manufacturer’s respirators to help mitigate this PPE shortage. This adapter is unique from others currently available, allowing the user to clock filter cartridges at any angle separately from the bayonet indexing orientation. Additionally, the adapter assembly uses RD40 threads a bridge across the adapters, by stepping MSA® bayonet to RD40x1/7 threads, and then back down from RD40 to 3M™. Although this was one possible solution already present with currently released RD40 adapters that wasn’t as clear cut to the average lay person that the RD40 could serve as a bridge to step up and down. Therefore an thingiverse page/number was assigned as a place holder for this possible assembly permutation in currently available solution space. And also dedicated page as a place holder for potential more direct future adapter that is lower weight design, smaller OAL, without RD40 threads if time present itself.

Part Description:

40MM_TO_3M_BAYONET_ADAPTER_INNER_SHELL_GEN5.stl

40MM_TO_3M_BAYONET_ADAPTER_OUTER_SHELL_GEN5.stl

MSA_BAYONET_TO_40MM_NATO_ADAPTER_GEN2.stl

RD40_GASKET.stl

Assembly shown is composed of adapters released previously:

MSA® Bayonet to 40MM NATO (RD40x1/7) Adapter
https://www.thingiverse.com/thing:4287482

40 MM NATO to 3M™ Bayonet Adapter
https://www.thingiverse.com/thing:4245358

This combines the two part files together, along with the RD40 gasket. A more streamlined, smaller OAL, lighter weight, and more direct design may follow later. However will have to be designed for left or right hand side specific to ensure typical filter orientation. And believe this current solution is more ideal allowing user to clock to any position independent of the bayonet.

Disclaimers/Risks:

1.) Use Proper Gaskets and Assembly Notes

Requires gasket/o-ring, below bayonet to ensure proper seal between cartridge and bayonet, shimming maybe required. Ideally source OEM MSA gasket, MSA 10018496, or some gasket or O-ring that is nominal ID 25.5 mm or ~1.0 in. Note using different durometer will result in lesser or greater friction bayonet engagement than from OEM.

2.) Perform Proper Negative Pressure Test

Follow SSPs established by your institution or workplace for further guidance. But in general, don your respirator, adjust straps till taught against face, ensuring no obstructions around the periphery of the seal against face either due from hair, facial hair, or otherwise. Exhale deeply. Cover all inhalation ports. (Typically, most full face or half face respirators have two filters, so cover those intake ports with your hands. If your running only one filter, ensure the opposite port has filter cap in place.) Now inhale deeply. The mask should suck tightly against your face without any air leakages. Re-test if adjustments are required at gasket/o-ring interfaces at the adapter.

3.) Use At Own Risk – Temporarily Solution Only Until Supply Chain Normalizes

3D printing materials are not resistant to many solvents, are water soluble, and degrade when exposed to chemicals, heat, and UV/sunlight. 3D printing this adapter is only a temporarily ad-hoc solution against biological contagions. In addition to using a properly calibrated 3D printer, due to tolerances of adapters, if possible perform hot nozzle pass on all exterior surfaces, to reduce surface porosity for FDM based methods, otherwise SLS/SLA method preferred. Highly recommended users apply a thin layer of polyurethane clear coat on all exterior surfaces, spray or dip based methods, to help resiliency and durability for repeated sterilization and to reduce fomite transmission in printed infill layers. Once supply chains return to normal, users should purchase OEM OSHA/NIOSH/EN standard approved/conformed respirators, adapters and accessories for their institution and workplaces.