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Thread: positive pressure air respirator

  1. #1

    Default positive pressure air respirator

    After being frustrated from wearing a respirator for literally hours, and still inhaling dust and paint through ill fitting masks, I made a fresh-air, positive-pressure respirator. The positive-pressure ensures that any leaks blows air out and doesn't allow fumes in.

    I started with a new high quality paint mask capable of filtering dust, organic vapor, paint and pesticides. I converted the mask to positive-pressure by covering the filter cartridges with two rubber plumbing caps that have band clamps. I installed 1/4" barb fittings in each cap.

    I then filter the air from my air compressor through an homemade air dryer and two particulate filters and plumb the mask into the air line with a standard quick connect fitting.

    I made an air dryer by passing the compressed air through a copper coil of tubing, that is submerged in ice water. The air then flows into an air/water separator. The ice bath is effective in condensing the water in the air, thus allowing the air/water separator to function. Most air/water separators only remove liquid water. They are not effective in removing water vapor. The result is cool dry air to spray and breathe.
    Hope it helps.

    Last edited by Calpyro; September 3rd, 2007 at 07:17 PM. Reason: error
    M715 W/W, M37

  2. #2
    Join Date
    Dec 2003
    Giddings, Texas


    Cool idea. But, you could go ahead and do the next step. Buy a surplus gas mask with the huge face shield and plumb it in to your "keg" air supply.
    Remember if you didn't build it you can't call it yours.

    6.2 powered M715, 5 M1009's, M416, 2 M101's, 2 M105's, 3 M35's, M1007 6.5 turbo Suburban project called Cowdog.

  3. #3
    Join Date
    Dec 2003
    Lone Pine, CA


    We all know what that is and I see two functions offhand:

    1. a very effective means of not having to drop the spray gun every 3 minutes for a fresh beer
    2. it keeps the old lady off your back for your drinking habits now that the keg is camoflaged as an air dryer - funny how you need to replace the dryer housing every week or so

    Looks like a good method to staying safe with all the gnarly chemicals in paints these days. Seems they all recommend a fresh air supply type mask but those tend to be prohibitively expensive for the average hobbyist.


  4. #4


    I was somewhat concerned of inhaling air direct from the compressor without quality filtering. The combination of the air dryer, two particulate filters and the cartridge on the respirator ensures that any containments in the air are filtered.

    One cost factor that I have not figured is how long the cartridge on the mask will last with a steady stream of air flowing through it. The good thing is that the filter cartridges are pretty cheap at Home Depot.

    I am not familiar with surplus gas masks. They might work reallywell, but new paint masks can be purchased for around $40.

    One thing that I forgot to mention is that the air from the ice-cooled air dryer makes the air in the respirator not only dry but cool. The inside of the mask stays dry and doesn't collect sweat and moisture from exhaling. It makes the mask much more comfortable to wear for a couple of hours straight when it's not hot and gooey.
    M715 W/W, M37

  5. #5
    Join Date
    Jan 2007
    China Lake Naval Base, SoCal


    We do a lot of sand blasting in the hot weather and cold... here is a company that you can purchase an inline insert that cools the air 20 to 30 degrees and heats it with another insert. Pretty amazing. After using one I don't see how we lived in that 120 degree cabinet without it. It was about $70.00 and well worth it. They also have an in line filter but maybe more money than Calpyro's idea.
    Go Ahead, Make my day

  6. #6


    I agree about the nasty chemicals in today's paint. I painted my daughters Ford truck today with automotive paint that has isocyanate and requires a fresh air respirator. I did not smell a thing.
    M715 W/W, M37

  7. #7


    Sounds like a great idea. Be careful though with your air compressor. It turns out that carbon monoxide (CO) is produced by the oil used to lubricate most compressors. Purpose built breathing air compressors either are "oil free" (RIX) or else have special filtration systems and indicators to remove the CO or warn the operator of its presence.

    Since you are a firefighter, check with your air shop about testing your setup's output, they can probably test it for you or hook you up with a test kit to take a sample to send off.

  8. #8


    So far so good. Thanks for the info. I was not aware of the production of CO.

    However, I am a walking CO detector. I've been exposed so much over the years, that I get instantly aware of the presence of CO and get "light headed" in a anything over .09 parts per million. I have compared my "feeling" with my CO detector we carry on the engine and I am 100% accurate so far.

    Bad stuff, but it comes with the job.
    M715 W/W, M37

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