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  • Venting dust collector outdoors

    It seemed like a good idea at the time. I never liked the cloud of dust that flies of the dust-collector-filter bag whenever I started the machine. Since my shop is in a remote location I thought I would exhaust the air from my dust collector outdoors. Goodbye dust cloud, I assumed. I replaced the air filter bag on my 2 hp, single stage, dust collection system with a sheet metal reducer (20" to 10") and routed the air outside through a 10" flex pipe. When I switched the dust collector on I expected the shavings and sawdust to continue spiraling down into the collection bag while the air would continue going up as it always has, but into the new reducer and flex pipe, instead of the air filter bag.

    What actually happened was the entire contents of the collection bag emptied out through the new flex pipe faster than I could run outside to watch the fun. Clearly a plan B was needed so I placed a 45 gal collection drum outdoors beneath the discharge vent, hoping to capture the shavings/sawdust that way. Another fail! The discharged material bounced out of the drum.

    So now my yard is strewn with sawdust and my failures are piing up. I'm still motivated however to avoid the indoor filter bag. I am back to square one unfortunately. My current thinking is that I need a cyclone outdoors so that the air will separate from the sawdust and allow the drum to fill without splashing debris everywhere. Alternatively I suppose I could install a cyclone indoors and do the separation in the conventional manner ahead of my dust collector. What about modifying the collection area inside the dust collector or further reducing the discharge reducer? Clearly the filter bag which I dislike so much plays an important role in separation with this unit.

    Is there an easy fix? If anyone has suggestions I would love to hear them.


    Thanks,

    Robert I
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  • #2

    Re: Venting dust collector outdoors

    1. when you vent outside air neess to be replaced... if you have a wood stove it will come back down the chimney... could be bad and dangerous.

    2. install a cyclone system, just skip the filter and vent exhaust outside.

    3. if #1 applies... and it's not a wood stove, it may get cold when all your warm air is sucked out being replaced by cold air (winter months that is)


    I wanted to do this, but I have a wood stove & I like working in relatively warm shop.
    nnieman likes this.
    [insert something witty here]

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    • #3

      Re: Venting dust collector outdoors

      I have a Thein separator and vent outside, it blows into a bush and you can barely tell any dust exits there at all. Inexpensive to build, and quite effective. That said, we have zero combustion devices in the house. If we had anything like a furnace or wood stove, I would not vent outside.
      nnieman likes this.

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      • #4

        Re: Venting dust collector outdoors

        I really appreciate the responses so far. Combustion heat and temperature are not part of the equation. The only heat is passive solar which is warmer than outdoors but still chilly on a cold day.

        Regards,
        Robert I

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        • #5

          Re: Venting dust collector outdoors

          I thein type separator or barrel lid separator are pretty decent in the situations. A Cyclone separator is even better as it ramps up the speed of the fines and pulls them out of the airstream. Do you have any pictures of your set up and where were you originally collecting chips (bag or bucket)?

          is the blower before or after the collection chip bag or container?
          For every action there is an equal and opposite reaction.
          Sir Isaac Newton.

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          • #6

            Re: Venting dust collector outdoors

            Just a guess....

            I wonder if the problem has to do with pressure and flow. When the filter bag is in place the inside of the filter gets coated with a thing that I think I is called a "cake"? The cake is effectively a restriction, which slows down the flow of air, allowing the larger chips to fall out of the circular air flow at the collector neck (cyclone?). When you remove that restriction and allow the air to flow unimpeded to the outside you change the nature of the "neck" at the collector and it becomes a venturi? and sucks all the material out of the collection bag. I am surprised that the collection bag did not get sucked up into the discharge pipe.

            If I am correct, you could try reducing the end of the outlet pipe to a very small diameter (think "cone") and experiment to get the correct amount of restriction so that your venturi goes back to being a cyclone ...

            There it is, incorrect terminology and all .... fire away !!
            Last edited by John Bartley; 03-09-2018, 08:12 AM. Reason: spelin ... agin!

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            • #7

              Re: Venting dust collector outdoors

              Click image for larger version

Name:	dustcollectorinside_1952.JPG
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ID:	1171585 It's really great to have all this brain power working on my problem. Thanks again. John I think you've described the situation well. The filter bag doesn't get sucked into the machine because it normally hangs by the top from a hook and it's clamped at the bottom. Rather than restrict things though, I'm really intrigued by the Thein idea which in theory would increase my collector's capacity. Matt requested photos so I'm attaching one of the outside with the reducer attached to where the filter bag normally hangs. The other shows the interior Click image for larger version

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ID:	1171584

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              • #8

                Re: Venting dust collector outdoors

                LOL. You pretty much made yourself a upside down cyclone. That ramp is being used backwards now and the chips speed up in the cone and will just go straight out the top.

                Click image for larger version

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                Last edited by Matt Matt; 03-09-2018, 09:17 AM.
                For every action there is an equal and opposite reaction.
                Sir Isaac Newton.

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                • #9

                  Re: Venting dust collector outdoors

                  Thank you for writing this thread I made the same assumptions and wanted to vent my dust collector outside into a barrel. I am debating moving the whole collector outside now after seeing the issues you had. The area where the dust collection would be is under a bedroom window maybe 10 ft away. My Shop is tiny < 200sq ft. and I have many machines. so getting rid of the dust collector or sticking it to the wall and running it outside make a lot of sense. I do not heat the shop. How did you end up?

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                  • #10

                    Re: Venting dust collector outdoors

                    It would be good if the OP came back and let us know how he ultimately resolved this. I think if he put a Thien baffle ahead of the DC inlet that would remove 90% or more of the wood chips and only the fine dust would be exhausted outside. One additional thing I would do is rather than taper the exhaust immediately, I would run the exhaust up at least a few feet at the full 20" diameter before tapering down to 4" or 6" out the wall. The reason for this is to reduce the air velocity so the dust can fall out of the airstream and fall back into the bottom bag. You could also leave the upper bag in place and build an enclosure outside the bag say 4" bigger diameter than the bag with a 6" vent off the top to the outside. If you did that you could experiment with and without the bag to see whether the bag makes a difference.

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                    • #11

                      Re: Venting dust collector outdoors

                      I put the whole dust collector outside when it's running. It's on wheeled base. No heat in the shop. Toronto's not so cold most of the year.

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                      • #12

                        Re: Venting dust collector outdoors

                        Are you in a remote area or do you have a quiet collector? I know my neighbours would scream blue murder if it were overused day after day and I wouldn't blame them.
                        "Do it Right!"

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                        • #13

                          Re: Venting dust collector outdoors

                          The collector isn't too loud.

                          More importantly, I do complimentary snow removal for all of my neighbours.

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                          • #14

                            Re: Venting dust collector outdoors

                            Maybe my neighbours and I can help with some moving expenses.
                            "Do it Right!"

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                            • #15

                              Re: Venting dust collector outdoors

                              We don't get much snow here. Less and less every year too.

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