3D Printing Ventillator Valves

3D Fabrication
#43

thank you for your feedback and knowedge.

what about vacu form? would that produce less porous materials?
are there other fabrication methods?
what if it was a metal socket for the filter fitment?
what if this was supplemented with an exhale valve?

The 3d printed design is mean to be thin, and somewhat malleable, and can be supplemented with EVA foam around the edges, the way a n95 mask is.

And you are correct, The surgical masks are not intended to protect like an n95. This is precisely how dire of a situation i am painting. nurses in the general floor (not the quarrantine wards) are reusing general purpose surgical masks. How many of them are being exposed to asymptomatic carriers? How dangerous is it for nurses to reuse equipment that is expressly porous and not reusable even with washing?

the print design i am proposing is washable with soap and water. it’s not sterile. But then again not many things are, and it’s a vast improvement over our current n95 shortage worldwide. I’m not saying people want to replace the n95. im saying the n95s are rapidly running out.

#44

cross posting. the anecdotes are pouring in. help is needed. we have so many printers sitting dormant.

#45

And right there you’ve lost me.

You need to learn a bit more and read some. Start with the paper Freddy linked.

Hint: The size of particle specified for N/P100 is the worst-performing size and the filter is more effective on both larger and SMALLER particles.

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#46

yeah i’m retooling this a little bit still. my understanding from medical people is the real goal is filtering out airborne moisture that carries these viruses.

I am currently in the process of gathering this formally

#47

Depends on the plastics, but you still have to account for fitment.

I’m referring to fitment around the face, not the filters. Filters will not be the source of air intake if fitment is not correct.

Two problems: first, it doesn’t solve the breathing in problem; second, it now allows for the medical professional to contaminate those they are treating. The choice of n95 is particular in that it protects both the patient, and the wearer. Whereas a typical surgical mask only protects the patient (beyond basic blood splash for the wearer). In a medical environment, especially those involving triage who interact with the most people, a crucial component is preventing yourself from becoming a transmission vector (especially with an asymptomatic incubation period).

you can’t properly dry these masks, and the introduction of moisture and grooves that are difficult to clean introduces bacteria growth. I’m not talking autoclave sterile, I’m talking I wouldn’t even trust an FDM printed piece of PLA to use as a dinner plate without a lot of planning. Quick reference: https://formlabs.com/blog/guide-to-food-safe-3d-printing/#fdm

If an official at a hospital reached out, and after noting these caveats still wanted them, I’d side with it. But right now I’m seeing a lot of enthusiasm and little reality check happening, and makers are known for being passionate about doing something but not explaining things well enough to people not already familiar with 3d printing. I’d be willing to wager that the same group of people asking for these masks to be made aren’t aware of the implications of FDM prints or the common filament choices in a sanitary environment. We are, and an important point to determine is if they’d still want the prints knowing that they are not cleanable in the ways people imagine they are, and once they try them if the loss of breathability and fitment impacts ability to do work in a high-stress environment where one does not have the time to fiddle with it, or check the contents of that weather stripping in that design to see if it will cause a rubber allergy versus a well-known paper mask. What if two different brands are used, is one actually rubber and the other some different synthetic?

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#48

No no no. Don’t worry about the filter. The filter itself is too technical for any of us to screw with. It needs to be at least N95 or preferably P100/[quote=“brenly, post:46, topic:70024”]
my understanding from medical people is the real goal is filtering out airborne moisture that carries these viruses.
[/quote]

NIH has published many papers, free for us to read, on the efficiency of various masks. That’s the place to start.

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#49

Positive pressure and fitment around face matters much less.

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#50

I appreciate the feedback and caution. You guys rock!

Can we get more solutions that will work? Let’s think tank this! How would we seal a 3d print? make it completely water proof / smooth / less porous?

@mdredmond from what I’m reading: from nih.gov

Conclusions/Significance

Any type of general mask use is likely to decrease viral exposure and infection risk on a population level, in spite of imperfect fit and imperfect adherence, personal respirators providing most protection. Masks worn by patients may not offer as great a degree of protection against aerosol transmission.
Although this could imply that individual subjects may not always be optimally protected, from a public health point of view, any type of general face mask usage can still decrease viral transmission. Also, it is important not to focus on a single intervention in case of a pandemic, but to integrate all effective interventions for optimal protection.

in this table 1 (below), no protection is 1. with a reduced odds being expressed as an inverse proportion" as in: no protecton is 1 over 1 (1/1)

whereas if the person is only half as likely to get sick it is expressed as 1 over 0.5 (1/.5) which measures as 2. the “IQR” is short hand for bell curve from multiple tests:

Table 1

Median (IQR) protection factor by mask, by activity, by age category.

no activity nodding shaking reading walking
Tea cloth Adults 2.5 (2.1–2.9) 2.2 (1.9–2.5) 2.2 (1.9–2.7) 3.2 (2.5–3.9) 2.4 (2.1–3.3)
children 2.2 (1.5–2.2) 1.9 (1.5–2.3) 1.9 (1.4–2.3) 2.2 (1.8–3.7) 2.2 (1.8–2.4)
Surgical mask Adults 4.1 (3.1–7.2) 4.7 (3.4–7.3) 5.1 (3.2–7.6) 5.3 (4.3–8.0) 4.2 (3.1–5.7)
children 3.2 (2.2–4.1) 3.4 (2.7–5.2) 3.6 (2.7–4.3) 4.9 (4.0–5.3) 3.6 (2.4–4.2)
FFP2 mask Adults 113 (26–210) 82 (45–179) 91 (23–187) 66 (29–107) 99 (19–169)
children 18 (6.1–165) 13 (3.8–41) 18 (4.0–54) 35 (8.6–91) 15 (5.1–176)

so, what we see here, is simply a TEA CLOTH worn over your face cuts your chances of getting sick by HALF. not the particles, not the virii, but the actual overall getting sick being reduced by HALF

now with surgical masks. we’re looking at a QUARTER less likely to get sick. not a quarter less likely to get particles thru. not a quarter less likely to get some dust thru. but the OVERALL reduction in getting sick.

i would bet money (im broke) that a HEPA filter would be between those two. I’m liking those odds.

and i reiterate my words earlier. Perfect is the enemy of good enough. are these odds worth the effort? let’s keep the ideas coming!

#51

I’m referring to fitment around the face, not the filters. Filters will not be the source of air intake if fitment is not correct.

Sorry, my terms are all wrong. I meant the… shall we say screw hole and protective grid that would hold the filter material. I’m thinking any readily available material less likely to harbor fungi and what have you around the filter holder. If it’s preformed (think hardware store plumbing fixtures.)

I’m not talking autoclave sterile, I’m talking I wouldn’t even trust an FDM printed piece of PLA to use as a dinner plate without a lot of planning. Quick reference:

Just read through that. Yikes! good to know. The solutions I am seeing / work arounds are listed at the bottom of that article. It would be awful to have my mask smelling like my night bite guard at the end of sleeping (i use a denture cleaning kit)

So for vacu forming, what if we made the material, and then used a heat gun / pressure for final fitment? Then added a layer of EVA foam around it.

From the NIH study i linked above, even imperfect fitment still provides AMAZING amounts of protection.

In a medical environment, especially those involving triage who interact with the most people, a crucial component is preventing yourself from becoming a transmission vector

I’m not seeing the exhale valve being listed as a filtered component when I read into it. Is there a specific citation? I’m seeing that the exhale valve is meant to be as least resistant as possible to help the overall breathing effort take less work. Putting a filter on that exhale valve would not serve to reduce the overall effort. The INHALE however could be solved with… Multiple valves? Is the n95 easier to breathe thru than a type 8 home air conditioning filter?

Further still. since the coveted n95 mask isn’t even really much more than a wireframe to secure an airtight membrane cup so the breathing goes through a single filter. What thickness of plastic would still allow fudging on the fitment? I’ve got plenty of type 5 laying around that could be used to make semi flexible masks. add a wire frame to it? add enough EVA foam that fitment doesnt have to be as precise?

#52

Would somene who read the study that shows cloth masks are worse than nothing please link to it? I think it was @hon1nbo, but I cant find it.

I’d like to see if the study includes cloth masks with filter material, since that is what the sewing group is trying to do.

#53

Print a master in ABS/PLA, then make molds and cast the parts in resin.

Faster thru-put
Non-porous
more expensive

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#54

Hi,

I’m glad to see some serious discussion of the risk of porous 3D Printed materials not properly filtering COVID-19, or even being a great place for the virus to hang out in wait of a host.

The Czech Ministry of Health has worked with Prusa Research to develop a suitable 3D Printed Face Mask - Its not a filter, but can be manufactured fairly quickly (for a 3D Printed part), and may be cheap enough that it can be used as a single use item. (Though printing times are still probably too long to really justify that). You can find the design here.

DMS has all required equipment to build this, and materials needed are PLA and Acryilic, both of which can be sourced from local stores, so there is no bottleneck created by mail ordered materials. The headband can be printed on the PolyPrinters (probably 2 -4 per printer per batch), and the acrylic facemask can be cut using the laser cutters.

I know this is a big departure from the other plans I have seen in this thread, but it is 100% doable with equipment on hand, and has been reviewed by medical professionals.

Best Regards,
Justin

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#55

I’ve made no such claim, I’ve only been pointing that 3d printed items become a breeding ground for bacteria and do not clean well anyway

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#56

I assume you mean this?

Although it appears to be contradicted by this

At any rate, that should provide a jumping off point to any quoted studies…

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#57

So, Brenly, could you modify the petition so it doesn’t ask directly for where the responder works at? Specifically the address being “required field” is getting them nervous. Some people out there apparently have FB clauses so that if they mention their workplace in any way, shape or form, they can suddenly be liable for everthing on the FB page. It’s made a few people nervous about filling out the form.

I will happily resend it to my nurse and MD contacts from there.

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#58

thank you. let me go ahead and change that to a non required field. thank you

#59

Honestly I’ve been thinking about this 3D printing alot & I think it’s what most people are focused on because alot of people have them at home. But we’re Dallas Mother FUcking Makerspace. We have way more manufacturing capabilities than @home 3D printing. 2 x Vacuum formers for plastics and a machine shop that can turn out surgical steel parts in a few seconds. Lasers, don’t forget the freak’n lasers that make short work of plastics & hell the multicam might even been working for 3D profiles.

Been going through the CAD models of all these masks and they’re shit. We have the tools to do way better.

As far as valves We have 4 metal lathes that could crunch those out.

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#60

We have CNC lathes?

#61

Yes the sherline and it’s working with Fusion 360

#62

I tried getting some of this for filter masks, but they are sold out of 1.75mm filament. If you have a large nozzle on your printer, there is still 2.85 on the market.