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#### proppastie

##### Well-Known Member
Log Member
With the 3M organic mask I was still getting head-aches with the solvents in the Poly Fiber. I decided I needed a Fresh Air Mask or Supplied Air Mask. Not wanting to spend the $300-$500 these items normally go for .....off to E-Bay.

#### lr27

##### Well-Known Member
This thread was just referred to from a thread about epoxy. I once made a serviceable CPAP out of several 45 mm computer fans in series, with a bit of space in between. Even one of them would probably be enough to feed a mask through quite a few feet of hose. The type I used had two sets of blades in each unit, rotating in opposite directions. These are capable of more pressure than most computer fans. Something like this: http://www.delta-fan.com/Download/Spec/GFB0412GHS-CF00.pdf There's a picture at the end. Also note the graph on page 4, showing how the pressure is relatively constant over a wide range of flow. This is nice to have. Anyway, you can find older versions of these fans on eBay, cheep. New, they're $25 or$30 from Digikey. I needed 4 of them for the CPAP. I got the CPAP debugged very shortly before the wheels of bureaucracy had finally turned enough to supply me with a commercial one. The commercial ones are better, but mine worked ok.

Hint: Keep the mice out of your air supply. Not sure I'll ever use mine again. They nested in the sound absorbing material I was using. Also, make sure you can back away from the work and rip the mask off in a hurry if something catches fire and you get a face full of smoke. That means, don't work in tunnels full of toxic gas! This seems VERY unlikely, but chances are something in your setup will be flammable, and, if there are any, the flames WILL be fanned. Maybe I'm too paranoid. Worked in the medical device world for a while, where we had to watch out for flammability in materials.

Log Member

#### Pops

##### Well-Known Member
Log Member
Whatever you can make to work, you have to have clean fresh air. A local retired airline pilot bought my buddies Jr Ace project and died 2 days after painting the Ace from the fumes of the paint. What ever you buy for the fresh air will be some of the best money spent.
Bathroom fan sounds like it would work, low pressure and higher volume. Make a sheet metal or plywood box and make a filter for the inlet air.

#### Kyle Boatright

##### Well-Known Member
Whatever you can make to work, you have to have clean fresh air. A local retired airline pilot bought my buddies Jr Ace project and died 2 days after painting the Ace from the fumes of the paint. What ever you buy for the fresh air will be some of the best money spent.
Bathroom fan sounds like it would work, low pressure and higher volume. Make a sheet metal or plywood box and make a filter for the inlet air.
I don't know that you need a filter. Just set it somewhere where it'll be sucking clean air.

#### lr27

##### Well-Known Member
A cheap electric airbed inflation pump might be worth trying.
CPAP Mark 1 used one of those. It would probably work.

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The longer your hose, the more back pressure. I wonder if a bathroom fan wouldn't need a bigger hose. For CPAP Mark 1, I used a corrugated hose intended for pumping out your basement with. Above a certain air velocity, it would kind of whistle, but I guess that wouldn't be a big problem for someone who wasn't trying to rest. A 72 cubic foot scuba tank, as I recall, is good for a long time at or near surface pressure. Two or three hours, I think. So if your mask didn't leak horribly, I imagine you could get by easily on several times that. The fan probably needs to go faster than you can inhale, but running all the time unless you have something fancy set up.

#### Kyle Boatright

##### Well-Known Member
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The longer your hose, the more back pressure. I wonder if a bathroom fan wouldn't need a bigger hose.
I used about 25' of corrugated 1.5" (?) pool cleaner hose. It provided a wash of air under my homemade hood. I'm telling you, it worked really well.

#### proppastie

##### Well-Known Member
Log Member
nice thing about the vacuum cleaner motor is that it comes with hose, hook-ups ,...you will not have to make an enclosure/case like for a bathroom or computer fan. If you need 110V then buy a cheap house vacuum...... But you might want a new one so as not to be initially sucking dirt from your living room. The little 12V vacuum I had about 50 ft of pool hose, with no problems supplying plenty of air to the mask and flood out from the exit valve up to protect my eyes. It should certainly work with a hood I would think but I have not tried that.

#### wmax351

##### Member
I've used a legit CNBr (chemical nuclear biological rated) PAPR when I was doing some interior car bodywork after high school, which had me inside the car with fumes. I didn't smell them at all until I went inside the house and took off the hood.

But for the rest of the people that don't have one of those lying around from when your dad's hospital had one flown in for a SARS rule out...

The basic device is a battery operated centrifugal fan that pulls air through a set of filters. Doesn't even need all that much air. You can test for breach by using a noxious substance. For critical stuff (like level 4 biohazards, smallpox, etc) you actually go through a room with some tear gas. But any highly smelly material will work.

The hood for the home version may be best obtained by getting a disposable one. They go through dozens when a patient has TB etc, so they shouldn't be too expensive. Also take a look on surplus sites.

https://www.ebay.com/itm/ONE-3M-BE-10-Tychem-White-Respirator-Hood-Size-Large/163333404752

You can also get a real one (sans filters) for not that much money. Battery is easily jury rigged with anothe power supply or cordless tool battery. https://www.ebay.com/itm/3M-BREATHE-EASY-BUTYL-RUBBER-HOOD-FR-57N10-PAPR-RESPIRATOR-no-battery-filters/272590139199

These type of things are like airplanes. The certified stuff costs lots, and a lot expires, so is much cheaper when you buy it expired or undocumented, for a less critical job (still needs to work, but if you smell fumes, you stop, and you don't get anthrax).

#### jmt1991

##### Well-Known Member
that looks like a real nice item,....which mask/hood did you get
I got the full hood due to the fact that I am using 2K polyurethanes and wanted as much protection as I could get.
It's nice not having your eyes get dry from the fumes, and it has a replaceable HEPA filter built into the blower, too.

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