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Thread: An idea that may help control exhausted dust.

  1. #1
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    An idea that may help control exhausted dust.

    And perhaps not new.
    So, of those of you who vent your DC outdoors, are you plagued by that same dust being drawn in as replacement air?

    A couple of days ago an idea came to me how to remove much of that air born dust.
    That idea, and maybe it's dumb or maybe it is in use.
    I have not come across it anywhere.

    Why not set up a patio mist and arrange the nozzles such as to remove some, perhaps most, of the dust out of the air at the area around the exhaust duct.
    Cleaner air for those outside nearby and no more pulling exhausted dust back inside.
    Mockers welcome.

  2. #2
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    Not gonna mock you on a keen idea. I have seen auto paint booths that use that technology for exhausting fumes from their paint rooms. Works well and is EPA and OSHA compliant.
    Good idea Bill.
    My Dad always told me "Can't Never Could".

    SWE

  3. #3
    Can't mock it.

    I once considered venting into a large bucket of water. The idea being that the cyclone would probably have enough pressure to blow through 6" or so, and hopefully only clean air would escape the surface.
    But I never tried it.

    I like your idea better: No added back pressure and better chance of wetting all the fines.

    Except, how would you keep this from becoming a giant, muddy mess on the ground?

  4. #4
    It would work for 5 months of the year, here

    ;o)
    Carpe Lignum

  5. #5
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    Being a KISS type of guy, if I ever vent my dust collector outside, I will let the make up air into the shop from the other side of the house...
    Too much to do...Not enough time...life is too short!

  6. #6
    Not a bad idea at all. Perfect year round for someone living in Arizona but not so much someone living in Minnesota for at least 6 months out of the year. You definitely would want the mist system to turn on and off with the cyclone.

  7. #7
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    If you are venting outside without a cyclone, you mean a large pile of chips/dust then (not sure if this is what you mean or not). If you wet this as you go, you will risk spontaneous combustion and a fire.

  8. #8
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    Very creative idea, however it is more challenging than you might think. Having designed industrial sized systems it is very difficult to capture the finer dust. In order to work the water must impact the dust particle, but the fine particles “dance” around the water droplets and don’t get captured. It take a lot of water with a precise flow pattern in a closed pipe to be mildly effective

  9. #9
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    Waterfall curtain and a pump?
    - After I ask a stranger if I can pet their dog and they say yes, I like to respond, "I'll keep that in mind" and walk off
    - It's above my pay grade. Mongo only pawn in game of life.

  10. #10
    Where I worked we had a downdraft bench that pulled the air through a bath of water. The wet air hitting sloped water impinging filters and then through the impeller before being directed back over the sanding area. The company had it because of several filter fires from the hot sparks when grinding steel aircraft parts. The metal dust in the pleats catching fire. I never got to see what the underwater configuration looked like when it was open for maintenance but I wish I had. The same company has units for ducted systems that likely work the same. http://www.hydrotron.net/products/ductedcollectors/

  11. #11
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    Industrial air cleaning processes mostly use two techniques, dry filters and wet scrubbers. As John says, it's difficult to get the dust particles attached to the water droplets. Then it's difficult to collect the droplets. Then it's difficult to clean the water. If you let the droplets evaporate the dust it released again. If you put the droplets on the ground, much of it will be released again. But back to the first problem, it takes a lot of horsepower to make the droplets small enough to work. Best to stick to filtering out the dust. Filtering and venting outdoors will improve your air quality without much worry about the effectiveness of your filters.

  12. #12
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    I shoot the dust and chips into a 4' wide x 8' long x 4' high box on a trailer. The stream enters one end, and swirls around. There is 2' x 4" framing to act as baffles. The amount of fine dust coming out is not much. It's also on the east side of the building. In fair weather, the prevailing wind is from the west. Rainy weather has an east wind. Most of the time, the fine dust settles in the meadow. There's enough distance and corners so that the dust doesn't reach the air intake.

    Make up air is from the other end of the building, on the west side.

    Keeping the shavings and sawdust dry is most paramount. 180 days a year, I burn 10 gallons a day as fire starter in a masonry heater. My sister uses the pine for cat litter, and a farmer uses the rest as bedding.

  13. #13
    My cyclone exhausts on the east wall of the shop, and I open north and south windows during nice weather. Hardly notice any dust except when using the wide belt sander, and only if I happen to look out the east window.

  14. #14
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    Quote Originally Posted by John Isgren View Post
    Very creative idea, however it is more challenging than you might think. Having designed industrial sized systems it is very difficult to capture the finer dust. In order to work the water must impact the dust particle, but the fine particles “dance” around the water droplets and don’t get captured. It take a lot of water with a precise flow pattern in a closed pipe to be mildly effective
    John, is it a matter of electrical charge?
    Might an ionizer prior to exiting the duct be helpful?

  15. #15
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    In theory it should work. The problem is the old saying: In theory theory always works. In practice it doesn't.

    The water has to come in contact with the particles for them to be washed out. If you just try to mist water at the discharge exit the water won't find a lot of the dust because of the air velocity. Google images of 'impingement scrubber' to get an idea of what industrial equipment looks like.

    But don't let us nay sayers talk you out of it!

    William Hodge's box method combined with a water spray *might* work. Have the DC discharge into a large container. Have a baffle(s) in it to slow down and diffuse the gas flow. A water spray would now have a chance to contact the dust and collect it.

    Since wood wouldn't be a good idea for the container an old drum would be a good start. It might not work but you have fun building it then it's all OK.

    Where I worked the impingement scrubbers had 400 hp fans to pull a draft through them. The water flow was 600 gpm on the smaller ones, over 1000 gpm on the big ones. Building a scrubber that works is pretty involved.

    If you build something that works make sure you post it! I would be shocked, I mean enjoy to see something that works.

    -Tom

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