40MM NATO (RD40x1/7) to Sundstrom SR Series Filter (SR100/200/900) Adapter

This prototype design for a 40MM NATO (RD40x1/7”) gas mask thread to Sundström SR series respirator (SR100/200/900) filter adapter. This adapter makes any RD40x1/7 threaded full face CBRN masks compatible with Sundström SR series line of chemical, combination, and particle filter cartridges to help mitigate PPE shortages by expanding greater cross compatibility of respirators and filters to other manufacturer models.

Part Description:

40MM_NATO_TO_SUNDSTROM_FILTER_ADAPTER_BASE_GEN1.stl

40MM_NATO_TO_SUNDSTROM_FILTER_ADAPTER_END_CAP_GEN1.stl

40MM_NATO_TO_SUNDSTROM_FILTER_ADAPTER_MAIN_GEN1.stl

40MM_NATO_TO_SUNDSTROM_TPU_GASKET_GEN1.stl

Initial model release of three part assembly, for ease of 3D printing, with included TPU gasket if user cannot source O-ring or gasket material from local hardware store.

Disclaimers/Risks:

1.) It would appear that the non RD40x1/7 threaded SR series of filters feature a gasket on the filter side and also relying on the silicone sleeve on the respirator side attachment. However, since I do not have SR series filters or respirator, I could not ascertain the o-ring dimensions to design an adapter to seal against OEM gasket on filter side, and because of my concerns with using TPU to replicate precisely the geometry on the respirator side, I opted to use an alternative method to seal against SR filter. A threaded end cap applies compressive force on the angled outer face of the filter cartridge, which seals on the OD of the base of the filter cartridge against adapter TPU gasket. Ensure positive seal by tightening provided threaded end cap . See cutaway diagram to see interface of adapter. Recommended user place witness clocking marks to ensure that the end cap doesn’t back off during prolong use or routinely press check to ensure seal.

2.) 3D printing materials are not resistant to many solvents, are water soluble, and degrade when exposed to chemicals. 3D printing this adapter is only a temporarily ad-hoc solution against biological threats. Once supply chain return to normal users should purchase OEM OSHA/NIOSH/EN standard approved adapters and respirator accessories.

Dev. Notes:

5/04/2020 – Initial model release. In work, pending support 3D printing community for any fitment and model revisions.