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  • Question about pressure equalization hose for dust bin garbage bag

    As some of you have seen in another thread, I am updating my dust collection system with a 2HP Oneida cyclone. I plan to use clear garbage bags in the dust bin so I built an insert to hold the bag in place while the cyclone is running. This works okay, but I read some suggestions to use a small hose between the cyclone inlet and the outside of the bag to equalize the pressure instead of using the insert.

    I gave this a try with some 1/2" inside diameter hose and it is not working for me. As you can see if you look closely in the second photo, the bag is being sucked up into the cyclone.

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    I believe that my dust bin is air tight. As well, when I remove the clear hose from the dust bin and turn on the cyclone, I can feel some suction at the end of the hose.

    Does anyone have any suggestions on why this is not working for me? The only thing I can think of is that I am not drawing enough air from between the bin and the outside of the garbage bag and may need a larger diameter hose.

    Thanks for any suggestions.

    David
  • Thread Continues Below...

  • #2

    Re: Question about pressure equalization hose for dust bin garbage bag

    Usually an indication of an air leak between cyclone and container, doesn't take much. You might try the line down a bottom of container. The method of clamping the top to container would also be suspect. I've in the past also had a small slit in the transfer tubing between cyclone and container, but that was after many cleanouts.
    Last edited by John JMK; 02-14-2018, 08:51 AM.

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    • #3

      Re: Question about pressure equalization hose for dust bin garbage bag

      David,

      For optimal results, the hose needs to go through the wall of the bin (you'll need a connection that connects the tube coming from the outside, to the tube section inside the bin. The inside tube should terminate inside a shop made "sandwich" of foam made from 2 pieces of approximately 6" square, 1/4" foam that you place on the bottom of the bin. That way the suction will be holding the bottom of the bag to the bottom of the bin.

      Another possibility is that the amount of suction you're getting is inadequate. Unless I'm wrong (and we all know that's certainly likely!), the venturi effect of the air passing through that section of the inlet ducting us what's generating the suction in your arrangement. Perhaps that isn't enough? You may be able to confirm this by connecting your shop vac to the end of the hose leading to the bin and seeing if that makes any difference.

      I'm watching this very closely, as I've still only got the Oneida Bag-Grabber vacuum pump arrangement on my system, and it's not doing very well these days for some reason!
      All the best,

      Marty

      President of Kingston Wood Artisans https://kwoodartca.wordpress.com/

      Proud member of the Wadkin Blockhead Club

      Comment


      • #4

        Re: Question about pressure equalization hose for dust bin garbage bag

        Originally posted by DGB_WAT View Post
        As some of you have seen in another thread, I am updating my dust collection system with a 2HP Oneida cyclone. I plan to use clear garbage bags in the dust bin so I built an insert to hold the bag in place while the cyclone is running. This works okay, but I read some suggestions to use a small hose between the cyclone inlet and the outside of the bag to equalize the pressure instead of using the insert.

        I gave this a try with some 1/2" inside diameter hose and it is not working for me. As you can see if you look closely in the second photo, the bag is being sucked up into the cyclone.



        I believe that my dust bin is air tight. As well, when I remove the clear hose from the dust bin and turn on the cyclone, I can feel some suction at the end of the hose.

        Does anyone have any suggestions on why this is not working for me? The only thing I can think of is that I am not drawing enough air from between the bin and the outside of the garbage bag and may need a larger diameter hose.

        Thanks for any suggestions.

        David
        I used a brass 90 elbow with a male pipe thread on the inside -barb on outside and cut a union off to make a nut to hold it from the inside. I put mine right in the bottom edge and taped a red sanding pad over it. It works great with just a 3/8" air hose hooked up to a 45 gal barrel.

        Comment


        • #5

          Re: Question about pressure equalization hose for dust bin garbage bag

          Originally posted by John JMK View Post
          Usually an indication of an air leak between cyclone and container, doesn't take much. You might try the line down a bottom of container. The method of clamping the top to container would also be suspect. I've in the past also had a small slit in the transfer tubing between cyclone and container, but that was after many cleanouts.
          Hi John,
          I could have a leak, but if so, I have not been able to detect it yet. To test for a leak, I removed the dust bin from the cyclone and removed the flex hose as well. I then sealed the top of the bin with foil tape and used my compressor to blow air into the drum through the small nipple used to attach the 1/2" hose. I could not hear any leaks and the foil tape flexed up indicating I have some pressure. I know this does not assure a perfect seal, but it seems like a reasonable test. I may try the line on the bottom of the bin to see if that helps.

          David

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          • #6

            Re: Question about pressure equalization hose for dust bin garbage bag

            Originally posted by MartyFromKingston View Post
            David,

            For optimal results, the hose needs to go through the wall of the bin (you'll need a connection that connects the tube coming from the outside, to the tube section inside the bin. The inside tube should terminate inside a shop made "sandwich" of foam made from 2 pieces of approximately 6" square, 1/4" foam that you place on the bottom of the bin. That way the suction will be holding the bottom of the bag to the bottom of the bin.

            Another possibility is that the amount of suction you're getting is inadequate. Unless I'm wrong (and we all know that's certainly likely!), the venturi effect of the air passing through that section of the inlet ducting us what's generating the suction in your arrangement. Perhaps that isn't enough? You may be able to confirm this by connecting your shop vac to the end of the hose leading to the bin and seeing if that makes any difference.

            I'm watching this very closely, as I've still only got the Oneida Bag-Grabber vacuum pump arrangement on my system, and it's not doing very well these days for some reason!
            It could be that your foam is full of dust and is too fine for the job. Every second or third bag that I empty I blow the Red sanding pad off that I used to cover my fitting. Just a thought Marty.

            Comment

            • Thread Continues Below...

            • #7

              Re: Question about pressure equalization hose for dust bin garbage bag

              Originally posted by MartyFromKingston View Post
              David,

              For optimal results, the hose needs to go through the wall of the bin (you'll need a connection that connects the tube coming from the outside, to the tube section inside the bin. The inside tube should terminate inside a shop made "sandwich" of foam made from 2 pieces of approximately 6" square, 1/4" foam that you place on the bottom of the bin. That way the suction will be holding the bottom of the bag to the bottom of the bin.

              Another possibility is that the amount of suction you're getting is inadequate. Unless I'm wrong (and we all know that's certainly likely!), the venturi effect of the air passing through that section of the inlet ducting us what's generating the suction in your arrangement. Perhaps that isn't enough? You may be able to confirm this by connecting your shop vac to the end of the hose leading to the bin and seeing if that makes any difference.

              I'm watching this very closely, as I've still only got the Oneida Bag-Grabber vacuum pump arrangement on my system, and it's not doing very well these days for some reason!
              Hi Marty,
              Can you explain more about why the hose needs to go through the wall of the bin? Could I not get the same effect if I made the sandwich of foam on top of the brass nipple?

              I don't believe I have enough suction to hold the bag to the bottom of the bin. When I hold my hand over the end of the hose, I don't feel much suction. If I spread that out with a sandwich of foam, the suction will feel even less. I connected my shop vac to the nipple and it draws so much air that it pulls the bag tight against the maroon sanding pad I have on the inside of the bin. Once the bag is tight to the pad, it cuts off the suction. This tells me that I need to use something like the sandwich of foam you describe so the air cannot be cut off. I'll give that a try, but I don't think that will fix this problem since there is so little suction.

              I'll be sure to report my progress on this thread in case there is anything useful for you.

              David

              Comment


              • #8

                Re: Question about pressure equalization hose for dust bin garbage bag

                Originally posted by Wally in Calgary View Post

                I used a brass 90 elbow with a male pipe thread on the inside -barb on outside and cut a union off to make a nut to hold it from the inside. I put mine right in the bottom edge and taped a red sanding pad over it. It works great with just a 3/8" air hose hooked up to a 45 gal barrel.
                Hi Wally,
                Do you feel much suction if you remove the hose while the cyclone is running? I am using the exact same red/maroon sanding pad.
                David

                Comment


                • #9

                  Re: Question about pressure equalization hose for dust bin garbage bag

                  Originally posted by DGB_WAT View Post

                  Hi Wally,
                  Do you feel much suction if you remove the hose while the cyclone is running? I am using the exact same red/maroon sanding pad.
                  David
                  I feel suction but it isn't that strong. I have mine in the bottom of the bin though.Maybe try doubling your pad and see what happens.

                  Comment


                  • #10

                    Re: Question about pressure equalization hose for dust bin garbage bag

                    Your connection at the bin is fine. Your connection at the duct is wrong. You don't have vacuum there so your hose equalizer doesn't work.
                    The closer you get to the bottom of the cone the more equal pressure is to the bin. The bin is a dead end within the system that has vacuum pressure.
                    Move the end of your hose from duct to top of the bin where the 6" (or 8"?) hose connects between the body of the cyclone and your bin and problem goes away.
                    Remember, we are here to share, learn, and enjoy. Relax.

                    Comment


                    • #11

                      Re: Question about pressure equalization hose for dust bin garbage bag

                      Interesting to see this thread progress. I can't say I understand the science behind it, I just know that mine works great. I have the hose connected to the bottom of the barrel with a coupling like shown, and then have a brillo pad taped over the opening inside. The other end of the hose is right at the connection to the main outlet of the DC: I have a craftex 405 connected to a super dust deputy cyclone by a small length of 6" flex. The metal collar on the craftex outlet that the flex sticks onto, that's where I connect the other end of the hose.


                      I will say, I usually give my bag a "head start" ; after I change the bag on the barrel, I have a piece of hard board bigger than the bottom of the cyclone; with the barrel out of place, I start the DC and cover the bottom of the cyclone and let it run for a minute: after about a minute the bag will be sucked back tight against the barrel. Then I put it back in place and off to the races. I'm not sure how important the "head start" is, I've never tried it without doing it. Maybe it would still work well, I dunno.

                      Comment

                      • Thread Continues Below...

                      • #12

                        Re: Question about pressure equalization hose for dust bin garbage bag

                        Mo, according to most info connecting to the inlet side of the cyclone is recommended, I haven't seen any info on connecting directly to cyclone body. Wouldn't the connection to the cyclone body constitute an air leak that would allow dumping fines into the filters? I'm no engineer so maybe there's something I'm missing. By the way the inlet connection worked on my CV1800 when I had it.

                        Comment


                        • #13

                          Re: Question about pressure equalization hose for dust bin garbage bag

                          Originally posted by mreza View Post
                          Your connection at the bin is fine. Your connection at the duct is wrong. You don't have vacuum there so your hose equalizer doesn't work.
                          The closer you get to the bottom of the cone the more equal pressure is to the bin. The bin is a dead end within the system that has vacuum pressure.
                          Move the end of your hose from duct to top of the bin where the 6" (or 8"?) hose connects between the body of the cyclone and your bin and problem goes away.
                          Thanks Mo. That makes sense since the hose will connect from the inside of the bag to the outside of the bag to equalize the pressure between the two. I'll seal the hole in my ducting with some foil tape and drill a hole in the dust bin lid near the 8" hose inlet and make the connection there. Out of curiosity, are you still using your metal bag liner or have you added something similar to this thread?

                          David

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                          • #14

                            Re: Question about pressure equalization hose for dust bin garbage bag

                            My hose works intermittently so after cleaning my stuffed filters for the 3rd time I broke down and have a couple of crazy carpets as an insert. I hope I never clog those filters again because it really sucks cleaning them!

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                            • #15

                              Re: Question about pressure equalization hose for dust bin garbage bag

                              Originally posted by Peter in Maple Ridge View Post
                              My hose works intermittently so after cleaning my stuffed filters for the 3rd time I broke down and have a couple of crazy carpets as an insert. I hope I never clog those filters again because it really sucks cleaning them!
                              Maybe you should build the bin level detector I posted

                              regards, Rod.
                              Work is the curse of the riding class.

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