Announcement

Collapse
No announcement yet.

Discharging a Dust Collector Directly Outside?

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Discharging a Dust Collector Directly Outside?

    Will it do any harm to a dust collector's longevity or performance if it discharges directly to the outside air?

    Our work load is picking up and it looks like I may FINALLY be able to break ground on my new shop building in the spring. I've been working on the design for the better part of a year and a half. The last piece of the puzzle is laying out the DC piping, which will run under the floor. Over the weekend it occurred to me that also putting the motor/impeller unit under the floor and sending the discharge to a pile outside will save valuable floor space. It would also be easier on me. Instead of having to fool with emptying the bag and keeping the canister filter unclogged, I'd just periodically shovel the shavings into a wheelbarrow and roll them over to the brush pile, which is where they will end up anyway.

    I live out in the country and can legally do this. There are no neighbors close enough to be affected. The shop's main room won't be heated or cooled, at least initially and maybe not ever, so discharging the DC to the outside won't matter in that regard.

    Is it okay to do this? Or does the motor need the resistance of the bags/filter in order to operate properly?
    Last edited by LarryG; 01-11-2011, 06:01 PM.
    Larry

  • #2
    I remember reading a blurb on Bill Pentz's website saying its actually preferable to do what you've suggested from a health standpoint simply by moving the particles outside, I also remember reading (can't remember if it was Bill Pentz's site or someone elses') that if you should choose to vent outside, make-up air must be provided for balance, if there's heating equipment around, one would have to make sure there's no negative draft, and incoming air is suggested to be filtered; and if heating costs is an issue, one could install a HRV to compensate.

    Comment


    • #3
      Not sure about the question being asked, but you might want to double check the legality of just blowing your fines outdoors, espeically if this is a commercial shop. I think as a homeowner there is no problem, but as a business, there are a lot of added rules you need to follow...

      Add to this the added cost of blowing heated / cooled air outside, and it would make more sense to stuff the DC in a closet, with a filter on it, and then fit the closet walls with some filtered means of passing the air back into the shop... Like a hole in the door with a pair of allergen filters or something...
      Please like and subscribe to my YouTube channel. Please check out and subscribe to my Workshop Blog.

      Comment


      • #4
        Sorry, I have no answer as to whether some sort of "resistive load" is required on the DC, although I have seen a few applications of larger DCs in which they are set up exactly as you describe.

        On a side note, I note the irony of being under-worked while the building of your shop remains unstarted. With some time on your hands it's a shame that you can't be putting it to good use swinging a hammer. I'm reminded a Fabulous Furry Freak Bros. line about ....


        well, never mind. There's an equivalence, trust me.

        JR
        JR

        Comment


        • #5
          By venting directly outside you also have, when not in use, the outside vented directly to the dust collector. I would think there would be issues with moisture, bugs and the like. I can see the fine particles building up, glued together with the resin and humidity and gradually filling up the duct. Small rodents living in the duct and when the wind catches the dust and takes it to the clothes line or garden you may be living in the shop.

          Had a friend who vented a small one up through the roof like a plumbing stack vent. It made for an interesting roof and as I understand it was almost imposable to clean off of the asphalt shingles. And in his case the neighbors were a bit peeved too, at least that is not a problem for you.

          Bill

          Comment


          • #6
            actually the DC works best (highest airflow, less head loss) with lowest restriction, so removing the filter bags and stuff lowers the restriction to the minimum.

            Your main worry in this instance besides the potential mess and "pollution" outside and the loss of conditioned (heated or cooled) shop air (you already mentioned both of these) are:

            1. You must have a low restriction air inlet to the shop from outside, or else you will add back the restriction your removed with the filter bag. The 2 filter bag DC (assuming 20 inches dia. by 30" high) each has an area of approx. 314 sq inches top plus 1884 sq inches sides or 15 square feet. So you'd have to have an outside opening covered with the same micron filter fabric 30 square feet (that's approx a 7'x3.5' door size) which will bring the air restriction back to that of the 2 bags. Pleated canister filters have an filter area of about 110 sq feet. Larger area = less restriction for the same filter material.

            2. Just have an opening about 3 ft x 3 ft with no filter - this will probably keep the restriction reduction of removing the bags but but remember you will be sucking in about minimum 500 cubic feet per minute so bugs, pollen, airborne dust, leaves, grass clippings etc will be entering your shop like crazy I would think. If you were not real careful about placing the DC outlet downwind in the prevailing wind direction and the intake opening upwind you could end up with a sizeable amount of your dust ejecta back in your shop, with no inlet filter.

            3. If you just close off the room with normal door and window cracks to pull air thru then you will probably place a great restriction on your DC and it will not work well. It would be like sucking on a pinched off straw. The DC runs louder in this case and sounds like its working more but moves much less air. Maybe every time you go in the shop and open the door it will slam shut (or you won't be able to open it, depending upon which way its hinged).
            Last edited by LCHIEN; 01-11-2011, 08:10 PM.
            Loring in Katy, TX USA
            If your only tool is a hammer, you tend to treat all problems as if they were nails.
            BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

            Comment


            • #7
              I considered this once but someone observed that they had tried it and the only issue they had was one of noise. They said it can be quite noisy if you don't put on a silencer in the exhaust stream of some sort.
              --
              Any sufficiently advanced incompetence is indistinguishable from malice

              Comment


              • #8
                Sandor Nagyszalanczy's book (Taunton) has an example of exactly that. The climates where you cannot do it do to moisture are also the ones where you would have to have some kind of heating/cooling, so I expect it would be fine.

                You probably want to take some measures to make sure the pile stays where you want it, or is dispersed reasonably slowly.

                Comment


                • #9
                  Originally posted by LCHIEN View Post
                  3. If you just close off the room with normal door and window cracks to pull air thru then you will probably place a great restriction on your DC and it will not work well. It would be like sucking on a pinched off straw. The DC runs louder in this case and sounds like its working more but moves much less air. Maybe every time you go in the shop and open the door it will slam shut (or you won't be able to open it, depending upon which way its hinged).
                  I have visions of the shop walls sucking in when the DC is fired upů

                  I got nuthin'.

                  g.
                  "Be excellent to each other."
                  Bill & Ted

                  Comment


                  • #10
                    Originally posted by gsmittle View Post
                    I have visions of the shop walls sucking in when the DC is fired upů

                    I got nuthin'.

                    g.
                    Watch out for flying glass.
                    Bob

                    Bad decisions make good stories.

                    Comment


                    • #11
                      Some good points in these replies, not all related to DC performance.

                      I think Loring's thoughts about make-up air may be the key factor. As I said, initially the main room of the shop will not be heated or cooled. In the spring, summer, and fall, the windows will be open for ventilation much of the time, and that would take care of the make-up air problem. But the windows won't be open during the winter. The building will be fully insulated, so I won't want to open a window or door and lose whatever heat I've picked up from solar gain.

                      Another possible complication is that I don't live all THAT far outside the city limits (although the actual "city" is several miles away). Today, I can discharge the dust to the atmosphere. Tomorrow, maybe not, if the city limits expand again.

                      So I think I'll go back to the original plan of putting the DC in the least-obtrusive location I can find for it, and keep my options open to heat/cool the shop sometime in future.

                      Thanks, everyone, for your input on this.
                      Larry

                      Comment


                      • #12
                        Sorry I only saw this after you made up your mind so I guess this is just an added blurb.

                        The other issue I've seen mentioned a number of times in the past is that in some setups (larger impeller/smaller motor size combos) without restriction on the draw or output end you can cause the motor to pull too much current and overheat/slag.

                        Unless you're doing some unique homebrew application I would think just the ducting out through the wall to your pile may be enough to limit the top-end. Presumably you wouldn't be running without the internal plumbing attached so that probably wasn't a real-world concern anyhow.

                        Comment

                        Working...
                        X