On a recent trip to Quebec, I came across the old Dustfoe Model 66, hailing from the early post-war period, for sale in an antique shop for about CAD $20. It is actually quite beautifully designed, well-fitting and has ingenious, meticulous, patented parts (and for its time, nicely contoured functional plastic elements like pressure flaps, along with an attractive blue metal holding station... perhaps colored annodized aluminum?). Lining it up with the RS-1, you can see the cartridge concept, replacable filters, gasket, simple strap system, etc.
Our RS-1 project was in many ways an attemp to reinvent the reusable respirator as general workplace PPE in an intermediate category between a surgical mask and a full industrial respirator, for emergency use during the pandemic, and in the face of the collapse of PPE supply lines in the Spring and Summer of 2020.
We tried to engineer around the need for an exhaust valve, having an awkward giant box portruding from the facepiece, 'accordioning' the filter (could it be flat if we used the right material... therefore more compact and easier to mass manufacture...?) We learned quite a lot and even came up with some novel and ingenious design improvements. We also tried to introduce a reusable filter with advanced materials.
It was an all-out effort but incredibly lean and collaborative, where private investment and the good will of industrial partners was matched with some modest government funding as well as an initial test procurement for a department of the Government of Canada. We built our own lab-scale test environment and pushed as hard as we could, intent not only on solving these design and engineering challenges but to do it in Ontario, with full domestic production. Admittedly, the results did not keep pace with the need for instantaneous PPE production in the early emergency phase of the pandemic. However, we learned a great deal and we have arrived at a design that was very close to meeting regulatory requirements. We are currently considering what the final version will look like. Or will we find ourselves back at the beginning again?
~JH for GC