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Thread: Portable 12 volt HEPA air filter

  1. #1
    Join Date
    May 2011
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    Default Portable 12 volt HEPA air filter

    So my next project has been found. Upon looking through my favorite electronics store (Tanners off of Valwood and I35 north of Dallas) I stumbled across something that sparked my imagination. A 12 volt 88mm fan that had a warning on it. WARNING: protective grill required for use as the plastic fan blades will cut.

    Sweet!! That gives me an idea. This thing should flow a lot of air, so why not make a portable HEPA air filter!!!

    So that is my next project. I need to find a large air filter that is a true HEPA filter, and I need to make a housing.
    Prepare for the worst, hope for the best

  2. #2
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    Lakeside, CA
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  3. #3
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    Im looking at a small filter to try to keep this as portable as possible. So Im looking at HEPA vacuum cleaner filters, but Im also looking at prefilters too. My wife read an article the other day about the Yellowstone caldera and that got her concerned. Especially since we are about to take a vacation to Arizona in a few weeks.
    Prepare for the worst, hope for the best

  4. #4
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    I had some time to kill this evening so I pulled up the model number of the fan to find the specs on it. It pushes 80cfm, is brushless, pulls 1.35 amps at 12 volts, and online it sells for $16. I paid $4.95!!!


    So after I got home, I had to hook it up on my test bench. Boy was I surprised when it almost lifted out of my hand!!!! It should work great for a small HEPA filtration setup.
    Prepare for the worst, hope for the best

  5. #5
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    Ordered the air filter last night and a carbon prefilter as well. I ended up buying a rectangular filter (AER1) as it is the same as what we use in the house. It should be delivered in a couple of days. Later today Ill swing by the hardware store to pick up a 2X6 board which I will use to mount the fan and the filter. Might as well pick up some PVC while Im there so I can create a directed air flow.
    Prepare for the worst, hope for the best

  6. #6
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    I got the filter in and the 2X6 board. I also stumbled across a barely used conical automotive air filter with a base plate adapter which will be used to turn it into a prefilter. I hope to make some progress on it next week.
    Prepare for the worst, hope for the best

  7. #7

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    I'm followin' your project with a more than passin' interest.

  8. #8
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    Got some progress done today.


    If I were to build this again, I would use 2X8 wood instead of 2X6 as there is not much room between the AER1 filter and the outside of the wood. There is only about 1/2 of wood on either side.

    Tomorrow Im going to the hardware store to pick up a wood rasp. Ive never done much with shaping wood besides cutting with a circular saw, jigsaw, bow saw, ect. ect. The wood rasp will help me with building smooth transitions between the conical air filter to the HEPA filter, and then from the HEPA air filter to the fan.
    Prepare for the worst, hope for the best

  9. #9
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    Curious as to your reasoning using 2x wood...... maybe a picture would help me understand.
    Don't bring skittles to a gun fight.

  10. #10
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    Ill see if I can take a pic in a few.


    The AER1 filter measures, about 4 1/2 wide by 10 long by 1 1/2 thick. So what I have done is use 3 of the 2x6x12 boards. I hollowed out one of them so the AER1 filter fits inside the hollowed out area. The other two boards are used to taper the air flow down since both the prefilter and the fan need a 3 hole for the air to flow through. I hope this is making sense.



    I wired up the fan today so I could test the actual amperage draw. At 14 volt battery voltage, the fan pulled 1.2 amps upon start up and then it quickly settled down to 0.95 amp draw. So thats not too bad. Air flow does drop considerably when I put all of the pieces together so Ill be looking at a way to improve the air flow through the fan. Testing will continue after it is all together to see what the current consumption is. Im estimating the air flow dropped from 80cfm down to around 20cfm. At 20cfm, it would take 57 minutes for all of the air in a 12 by 12 room with 8 ceilings to be filtered. If I can get the air flow back up to just 40cfm then that 57 minute time will be cut in half (28 minutes and 30 seconds).
    Prepare for the worst, hope for the best

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