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Thread: Effect of leaks in dust collection system

  1. #1

    Effect of leaks in dust collection system

    While doing some checks on my DC I noticed a difference in current draw of about 2 amps when all of the blastgates were closed and then one 5" port fully open. That doesn't appear to be much but it can add up in electric cost in a year. So now I'm wondering how much I'm losing due to leakage. The biggest culprit in my system are the blastgates. Anyone else give any thought to this?

  2. #2
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    I installed a Magnahelic vacuum gauge to keep track of how much air I was drawing using the factory provided fan curve (Oneida 2 hp Dust Gorilla). With the duct blocked off at 0 cfm I noted the gauge reading (about 9" IIRC which corresponded with the curve). Then with the duct open but all gates closed read the gauge, and I was loosing close to 300 cfm. I went around with silicone and sealed all of the places I could hear air leaking, mostly the bends. What was left was mostly the blast gates, still leaking about 100 cfm. Not exact science, but it helped me seal up the system. Left gauge is total suction, right gauge is loss across the filter.
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    NOW you tell me...

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    Quote Originally Posted by Steve Mathews View Post
    While doing some checks on my DC I noticed a difference in current draw of about 2 amps when all of the blastgates were closed and then one 5" port fully open. That doesn't appear to be much but it can add up in electric cost in a year. So now I'm wondering how much I'm losing due to leakage. The biggest culprit in my system are the blastgates. Anyone else give any thought to this?
    If what you are describing is the current draw goes up by 2A when you open a blast gate, then this might be normal. With all of the blast gates closed, and no leaks in the suction side of the system, the blower isn't strained as much as when it is moving air.

    On my 400V 3-phase 3HP DC, with all gates closed, the blower draws 3.0A per phase. When I open one 5-inch gate, the current increases to 3.1A per phase. Opening additional gates doesn't affect the power consumption as best as I can tell.

  4. #4
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    Mike is correct that the least load and current draw will be with everything shut. But you are also correct that blast gates are the one place where there is likely going to be some leakage. If they are installed in the "correct" direction, tightening the thumb screw lock for the gate will reduce the leakage. But there will likely always be some and a little more when they are dirty enough that the gate doesn't fully close.
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    Jim please enlighten me,what is the "correct" orientation ? I Know that I have a few in different positions in my system.

  6. #6
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    That is incredible to be losing 300 cfm to leaks. What kind of ducting do you have?

    I am using 6" DWV, no glue or caulk, and home made gates. I have no leaks that I can hear or feel. Gates that I have bought leak. I had some plastic ones and some metal ones. The metal ones leaked a lot.

  7. #7
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    Specific to a particular design of course but, from Oneida:

    "Blast gates are designed to air seal in one direction with the plate toward the collector - tightening the thumbscrew toward the collector will result in less air leakage."
    "The Danish government believes that if we train 5,000 designers, and produce
    one Hans Wegner, the money is very well spent." - Ole Gjerlov-Knudsen

  8. #8
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    Quote Originally Posted by Mike Kees View Post
    Jim please enlighten me,what is the "correct" orientation ? I Know that I have a few in different positions in my system.
    The turn screw pushes the gate toward the DC (aways from the machine) so that sealing the gate isn't entirely dependent on the lower air pressure when the system is running to "seal" it.
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  9. #9
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    Thanks Jim that makes sense ,now I will have to check that out. One effect of leaks I discovered about a month ago is if there is a leak at the inlet of your cyclone it affects the efficiency of the system big time. Also sends way more fine dust into the filters. Somehow I had missed sealing that joint even after sealing everything else.

  10. #10
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    Mike, a leak in the connection to the bin will very quickly get you to saying LOTS of bad words when the filter gets packed with "stuff". That's a thankless job to clean up after! DAMHIKT!!
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    The most expensive tool is the one you buy "cheaply" and often...

  11. #11
    All of my blastgate turn screws were in the wrong position. Thanks for the heads up!

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    Another step you can take on the blast gates is to apply mastic around the joints on either side, as its challenging to seal those joints with tape given the lack of space on either side of the blast gate.
    There is a very fine line between “hobby” and “mental illness.” - Dave Barry

  13. #13
    I fired up the DC today after reversing the blastgate turn screws. Wow! What a difference it made. There must be some leakage in the system but I can't detect any.

  14. #14
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    Quote Originally Posted by Steve Mathews View Post
    All of my blastgate turn screws were in the wrong position. Thanks for the heads up!
    Ditto. I was exactly wrong 19 times. O well at least I was consistent. I have more suction as well,thanks Jim.

  15. #15
    Who knew something so simple would make a difference .....??? Again, why I love this place

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