
DIY Positive Pressure Suit - adammunich
http://civilpedia.org/p/?pid=336&t=p&h=Positive+Pressure+Suit
======
angry_octet
There are two major problems that I see:

\- Source of clean air: HEPA filter will get contaminated and needs to be
changed. UV sterilization might do it, but bulky and power intensive.
Otherwise carry your own gases -- extremely technical, likely to asphyxiate
yourself.

\- As soon as you go I to a red zone the exterior of the suit is contaminated.
Basically you need a disposable suit/gown outside the positive pressure suit.

Only other issue is that this is bonkers. Stay at home, wash your hands, wear
a face shield when out to prevent touching your face if need be.

~~~
dogma1138
Unless you are in a room with 20 infected people the filter won’t matter that
much.

A few layers of cotton is usually enough to filter 95%> of all 0.3 micron
particles this is because the filtration is based on the fact that the
thickness of the filter is orders of magnitude larger than the size of the
particles so the size individual holes at any given layer don’t matter that
much.

That said the majority of the benefit from this suit wouldn’t come from air
filtering but from the fact that you won’t get contaminated droplets on your
face and you won’t be able to touch your face with your hands after touching
contaminated surfaces.

~~~
Engineering-MD
Do you have a source for this?

~~~
coderintherye
[https://www.cambridge.org/core/journals/disaster-medicine-
an...](https://www.cambridge.org/core/journals/disaster-medicine-and-public-
health-preparedness/article/testing-the-efficacy-of-homemade-masks-would-they-
protect-in-an-influenza-pandemic/0921A05A69A9419C862FA2F35F819D55)

~~~
Johnny555
I think that study is testing the opposite what what this suit provides --
it's not testing protection of the wearer, but testing whether or not the mask
protects others:

 _The median-fit factor of the homemade masks was one-half that of the
surgical masks. Both masks significantly reduced the number of microorganisms
expelled by volunteers, although the surgical mask was 3 times more effective
in blocking transmission than the homemade mask._

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mkoryak
One time I biked to work (~5 miles) on a summer day (80+ F) wearing nothing
but underpants and a PPE suit from childrens' hospital Boston. The only thing
exposed to air was my face.

When I got to work, I was swimming in my own sweat. I remember taking it off
and draining buckets of sweat out of the 'sock parts'.

If this thing is air tight, I expect it would work about the same. That little
blower wont be enough to cool you down on a warm day and you will be enjoying
a sweat bath.

~~~
zxexz
What was the reason behind the strange cycling attire, if you don't mind me
asking?

~~~
EllipticCurve
In some sports this is kind-of normal procedure to reach a weight class before
a major competition. You go into a sauna or do sports in air-tight clothes and
lose a few kg of water. After getting weighted and assigned a weight class you
drink lots of water again

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dogma1138
Oh ffs were not dealing with the andromeda strain here.

If you need to go outside and you’ll be in occasional contact with other
people gloves and a face shield will do.

If you’ll be in constant contact with other people or in situations where air
circulation will be limited e.g. public transport or small offices then a
respirator / face conforming mask needs to be added.

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jefftk
I wonder whether hospitals could use something like this. Pipe in air from
outside to the helmets of healthcare workers. Everyone needs to be tethered,
which is pretty annoying, but maybe doable?

Maybe you could make one out of a snorkel mask (like one of the dodgy full-
face ones:
[https://smile.amazon.com/dp/B07BP6CTBQ/](https://smile.amazon.com/dp/B07BP6CTBQ/))
and a vacuum cleaner?

~~~
phendrenad2
In the 1971 film The Andromeda Strain, the biological containment lab has
these cool suits which have a tunnel you crawl through to get into the suit.
The suit never leaves the containment chamber. I keep thinking back to that
design, and wondering if that's the future of COVID hospitals. Something like
that wouldn't be that hard to mass produce at all.

~~~
pram
They also had a laser that burned off the top layer of your skin lol

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carapace
Don't miss the rest of that site. Mad genius.

[https://civilpedia.org/p/?pid=101&t=p&h=Basics+of+IEC+Fusion](https://civilpedia.org/p/?pid=101&t=p&h=Basics+of+IEC+Fusion)

or this

[https://civilpedia.org/p/?pid=30&t=p&h=Laser+Microscope](https://civilpedia.org/p/?pid=30&t=p&h=Laser+Microscope)

I've never seen _that_ before...

~~~
dTal
The "laser microscope" only goes halfway. You can deconvolve the diffraction
pattern and get a fully volumetric image! Resolution is an issue. One setup,
if your target is not moving, is to aim the projection at a desktop scanner.

~~~
carapace
OMG that would be awesome, can you elaborate a little?

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prostheticvamp
So, the filtration on this is a hepa filter. It’s a cool way to still get
infected

~~~
Johnny555
I'm not sure I understand this comment. I don't know if this suit will really
offer protection, but I don't see the problem with the choice of filter.

A HEPA filter has a stricter rating than the N95 masks that healthcare workers
use.

"HEPA, which stands for High Efficiency Particulate Air, is a designation used
to describe filters that are able to trap 99.97 percent of particles that are
0.3 microns"

N95: Removes 95% of all particles that are at least 0.3 microns in diameter

~~~
dragonwriter
The nominal rating is stricter, but is the certification process that the
claims of the nominal rating are actually met as strict?

There's what it says it does, and the probability that it actually does what
it says it does. Those are two different considerations.

~~~
Johnny555
That's a different argument -- whether or not the HEPA filter really is a HEPA
filter.

~~~
jlokier
And whether the seal around the HEPA filter that the HEPA filter is put inside
is airtight.

E.g. I've seen some vacuum cleaners which have HEPA filters reviewed as a bit
useless at filtering because the particles flow through small gaps around the
filter.

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swader999
I just roll with a T Rex suit, have the fan in the tail with an embedded pipe
that shoots air past a uvc light.

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ars
Please don't wear this while sleeping - it's missing some safety features, and
you can kill yourself by re-breathing air, without even realizing it.

~~~
spiritplumber
I took a nap in it. It's all good. You can't overpressure it if you want to
(that's what the lower valve is for).

~~~
ars
What would happen if the motor died? Would you still get fresh air? You are
risking your life sleeping in this.

~~~
spiritplumber
Part of why I used a blower rather than another type of pump is that you can
still breathe in. You have to force the air through with your chest, which is
tiring, but there's no danger. the idea is that you go out and get the blower
replaced, at that point

~~~
ars
You should add a second one-way value. Because with the open tube you are
breathing back in the same air you are exhaling.

Try it: Turn off the motor, and take shallow breaths, see how much air you
get.

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savrajsingh
A simpler version may just be a helmet that drowns your face in HEPA-filtered
air (so just positive pressure around your face / head)

~~~
dogma1138
It’s called a powered respirator they’ll cost around $200-250 for the ones
that just offer more comfort than full/half mask respirators to $500 that also
offer chemical/hardcover protection to $1000> for special uses like
welding/smelting work.

~~~
abakker
And, they’re great! They keep you cool, then keep particles out, and they
don’t need to seal so tight.

Source: have used one for welding.

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DoreenMichele
Makes me think of this:

[https://questionablecontent.net/view.php?comic=1315](https://questionablecontent.net/view.php?comic=1315)

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electriclove
This is awesome! Thanks for sharing!

Now, how much if I wanted to buy one? :)

~~~
spiritplumber
I spent about $60 for the parts overall.

The idea was to use parts that are still available easily, although I worry
about the scuba masks for it.

Our other builds are at [https://robots-
everywhere.com/re_wiki/pub/web/Cookbook.SaltM...](https://robots-
everywhere.com/re_wiki/pub/web/Cookbook.SaltMask.html)

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spiritplumber
Hi, I made this, if you have questions ask away!

~~~
khafra
If you had an expanded budget and were going to make some design changes for
longer-term wear, or more versatility/durability, what would they be? How
close to Quarian envirosuits can we get, exactly?

~~~
spiritplumber
If I had an expanded budget I'd get something designed for this purpose. This
was a bit of a McGyvering for hospitals that ran out of regular PPE suits.

If I was to change anything, I'd have more air go between the two layers, for
comfort. Or use a less noisy air source than an air bed blower.

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nexuist
Is it legal to wear these things in public? I feel like someone would
definitely call the cops on you out of fear.

~~~
adammunich
Why would it be illegal?

~~~
foxyv
Some places it is illegal to cover your face. (Banks, Government Buildings,
etc...) I would probably put a "Hi my name is BLANK" sticker on my shirt to
kinda offset that.

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kjs3
I'm betting he wore that thing for less than an hour total. In air
conditioning.

~~~
spiritplumber
I wore that one just to take the picture. I wore the test article one for 10
hours including a 4 hour nap. I don't have air conditioning in my home.

