strangeparts / gasmask Goto Github PK

This is essentially an open invitation to anyone who wants to make new one way valve designs. Currently the only design in the repo is a more-or-less fully printed design that relies on having a smooth build surface and works best with a well calibrated first layer and flexible build plate (eg. smooth pei spring steel). We should also have valve designs that use more off-the-shelf parts to allow a wider number of makers to produce working one way valves.

The one way valve should be designed around the 40mm nato male reference model to ensure compatibility with all of the masks in the repo. The nato thread reference length and outer geometry should not be modified, however the design of the tightening knob on the end is up to the designer.

Potential one way valve ideas include:

• Using a circle cut from a balloon to make the flap
• Using a flat door that seals on an o-ring embedded in the surface
• A valve that has the same geometry as commercial mask valves, so that replacement diaphragms can be purchased in bulk and installed
• Using a commonly available spring or rubber band to create the mechanism for the valve

Potentially draw inspiration from:

• https://www.thingiverse.com/thing:4462940 (center-retained tpu circle based)
• https://www.thingiverse.com/thing:4336351 (molded silicone/caulking? flap on compliant tensioner)
• https://www.thingiverse.com/thing:4239168 (center-retained balloon cutout based)

I know hhis has been mentioned elsewhere, but this seems like the place to stpre and organize ideas.

The device needs an exhalation valve. It needs to be located on the other side if the "inner mask", and the inner mask should not seal against the face. It should preferably be made such that the fresh air arrives on the outside of the inner mask, and is exhaled inside it.

Dead space should be minimised. This is the volume of gas that gets inhaled again after being exhaled. The current design has so much dead space, that it might cause carbon dioxide poisoning. Much of this can be removed with a carefully placed exhalation valve.

Testing is needed to determine the effectiveness of the existing canister design, as well as to aid efforts to safely shrink filter size.

I've made a couple attempts to fix this, the first of which failed. Because there is a horizontal seam between the body and the inlet plate, there is often a small gap that the diaphragm can get stuck in. It's not a breaking issue since it will only get stuck on one side allowing it to let air by, but it would be nice if it didn't do that since it may reduce airflow.

Just creating this in case my second attempt to fix fails too.

The current canister designs we have are all pretty long. For cheek-mounted canisters, it would probably be nice to have a design more like a pancake. Additionally, someone needs to determine what minimum internal volume we need for these designs to work for our desired usecases, in order to avoid making the canisters unnecessarily large.

We should also catalog these external designs somewhere (note: these are untested):

• https://www.thingiverse.com/thing:4236518
• https://www.thingiverse.com/thing:3858646

This honeywell north organic vapor cartridge seems to be only 4cm in length.

Weather stripping seems like a popular choice, we should test and document the available options to establish a recommended material and procedure for the face gasket

This might not be an issue. But it definitely a big disadvantage. I can't fit it on my Prusa mk3s. Which is a very common 3d printer. Maybe the Part from the filter could be closer to the mouth?

I think this is due to the exhaust channel. I would like to figure out how to squeeze more parallel exhaust tubes into the end, since currently the total cross section of the 4 existing tubes is less than the area of the other holes (intake and port between exhaust tubes and valve chamber).

It could also be the holes in the diaphragm, I haven't checked. I'll return to look at this eventually since it works as is.

[edit] It seems this issue has been expressed while I wrote this one. Sorry for the duplicate

Hi !

Thanks for your project ! It seems very promising however I think there needs to be an exhaust port on the mask. Since it is difficult to breathe through the filter, it would be greatly beneficial to expire effortlessly. It would also help to manage the humidity in the filter. I am speculating but I guess that a damp one would be less effective since the activated charcoal would be clogged up.

Here are some reference picture from a mask I used during my military service:

Behind the "grate" is a voice diaphragm. The two lower oppenings are the inlets and outlets. Each one of them houses a one way valve.

This is a close-up of the outlet

The gray opening is just the voice diaphragm.




The rubber of the valve is pretty thin so it may be possible to use balloons to make membranes. Their curved shape may be used to ensure a tight contact and mimic the bevel of the original one.

Regarding the nose and mouth separate area, it appears that its primary function is to unfog the lenses using fresh air. Since the eyes are extremely sensitive it makes sense to have only one effective seal around the mask.

Thanks again for your work and I hope to be able to help you further !

This gets mentioned every once in a while, so I'm just noting this here for when we have a full mask to test and evaluate whether an inner mask wall valve and/or inhale valve would help reduce fogging or improve the co2 situation.

Issue #5 has pictures of a commercial mask that seems to lack an inner mask valve.