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Thread: Minimum gauge for DC ducting?

  1. #1
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    Minimum gauge for DC ducting?

    Hi all,

    I'm finally 'hard piping' my DC system. I'm adding a super dust deputy cyclone to a Shop Fox 2 HP DC. I went to the local heating place today to price the duct work and ended up walking out with 5" and 4" pipe. After starting the conversation with "I'm looking for 26 ga. duct for a dust collecction system".

    Well....I got home and found that they sold me all 30 ga. snap-lock. I'm wondering if the 30 ga. is sufficient for the system, especially the 5" (I suspect the 4" will be o.k.). Has anyone actually had an issue with 30 ga. collapsing? FWIW, I'll have a total run of less than 20' of 5" in my 400 sq ft. shop with 4" runs of 5-10' after that.

    As an aside, I also ordered a set of switched blast gates and a Long Ranger controller box. I have had the remote version for a long time and it's done a good job, but I don't want to keep track of the remote AND be switching gates open and closed all the time. Anybody have this system and if so, what do you think?

    Thanks in advance,
    Chris
    "You can observe a lot just by watching."
    --Yogi Berra

  2. #2
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    You should have no problem with 30ga on 5"...
    Have been using that for about 25 years on over 45' of it...

  3. #3
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    Thanks Ed. I'm curious to hear from others (and also willing to do the experiment for $25...). I've heard rumors of collapse but wonder how common it really is.

    Best,
    Chris
    "You can observe a lot just by watching."
    --Yogi Berra

  4. #4
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    While some find 30 ga adequate, I have seen pics on this forum with 30 ga sucked flat. 26 ga for me, at least 4"-7".
    NOW you tell me...

  5. #5
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    Personally, I would go with 26 gage for dust collection. Typical 30 gage HVAC snap-lock can be made to work but it has a much higher risk of collapse in a dust collection application than the heavier gage "stove pipe". Remember, with DC, you have negative pressure which is the opposite of HVAC applications.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  6. #6
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    For what it costs to upgrade to 26 gauge, I wouldn't use 30 gauge. It may be fine with some blowers, but many will suck it flat. Considering the work that goes into installing the duct, it would be a shame to have to do it over.

    30 gauge spiral would probably be alright though. I have 26 gauge spiral & even the 8" duct holds up if I stand on it.
    Last edited by Frank Pratt; 04-27-2021 at 10:48 AM.

  7. #7
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    Thanks all. I went back this morning and will be swapping out for 26 ga. I suspect the 30 would have been fine, but started thinking about the fact that I'll have a fully closed system with all the blast gate switches. So everytime I turn off the system, it will be on full suck and have all the gates closed...
    "You can observe a lot just by watching."
    --Yogi Berra

  8. #8
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    Christopher, my system is fully closed most of the time. Blast gates open automatically when I start a machine.. and close when I shut it off...
    The dust collector also starts/stops automatically with any machine or any time I manually open a blast gate to vacuum floor, etc.

    For peace of mind, glad you are changing to heavier gauge... You will feel more confident about it...

    The system I use is X10 for control and on occasion the dust collector has started in the middle of the night due to power hits, etc and ran until the next day with ALL blast gates closed and have not had any problem other than electric costs.

    Just curious, can someone provide a link, etc where 30gauge has collapsed?? and what size/hp was connected to it ??
    Last edited by Ed Aumiller; 04-27-2021 at 7:36 PM.

  9. #9
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    Quote Originally Posted by Ed Aumiller View Post
    Christopher, my system is fully closed most of the time. Blast gates open automatically when I start a machine.. and close when I shut it off...
    The dust collector also starts/stops automatically with any machine or any time I manually open a blast gate to vacuum floor, etc.

    For peace of mind, glad you are changing to heavier gauge... You will feel more confident about it...

    The system I use is X10 for control and on occasion the dust collector has started in the middle of the night due to power hits, etc and ran until the next day with ALL blast gates closed and have not had any problem other than electric costs.

    Just curious, can someone provide a link, etc where 30gauge has collapsed?? and what size/hp was connected to it ??
    Wow. I haven't thought of X10 since my med school apartment. 40 years ago. 1985. While BSR was still in business.

    Are these devices still available?
    - When God closes a door, he opens a window. Our heating bill is outrageous & six raccoons got in last night. Please God, this has to stop!
    - Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read.

  10. #10
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    Alan, yes, still available.. go to x10.com

    What I use is microswitch on blast gates that close when they are open... this is connected to PF284 (Input A, Mode 3) which sends a signal to a x10 controlled outlet which turns on the dust collector... when blast gate closes it sends a signal to turn off the outlet (and dust collector)...
    Nothing fancy but it works great... depending on your dust collector hp, may require a relay for the higher current... I use a 110v relay to operate a 220v motor..

    I got tired of forgetting to open gates when using a machine, so made it all automatic...
    Last edited by Ed Aumiller; 04-27-2021 at 9:24 PM.

  11. #11
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    Quote Originally Posted by Ed Aumiller View Post
    Christopher, my system is fully closed most of the time. Blast gates open automatically when I start a machine.. and close when I shut it off...
    The dust collector also starts/stops automatically with any machine or any time I manually open a blast gate to vacuum floor, etc.
    What size is your blower motor & how many starts per hour is it doing? The bigger the motor, the fewer starts per hour, generally speaking. It's especially important to observe this with a blower motor because of the high inertia start. My blower specifies no more than 6 starts per hour.

  12. #12
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    Thanks Ed, I changed my mind primarily because the cost was minimal and I'm at the stage where I'm not interested in the lost time if a section did collapse.
    "You can observe a lot just by watching."
    --Yogi Berra

  13. #13
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    Ed,

    I cannot give you too many details, but a friend of mine collapsed 30 ga. snaplock (8" I think) pipe in his home workshop. He was using a 3HP professional Oneida cyclone setup. He ended up doubling up the 30 ga. on the longer runs, and put home made wooden collars around them to hold tight the second layer, about 5' apart.

    I use a 3 HP Oneida Gorilla in my shop, with 8 & 6" spiral HVAC pipe (unknown ga.) with no problems. I do have a 2 1/2" outlet that goes to the top of my RAS guard that has no gate and is always open. I figure it as a sort of safety valve.
    Rick Potter

    DIY journeyman,
    FWW wannabe.
    AKA Village Idiot.

  14. #14
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    Quote Originally Posted by Jim Becker View Post
    Personally, I would go with 26 gage for dust collection. Typical 30 gage HVAC snap-lock can be made to work but it has a much higher risk of collapse in a dust collection application than the heavier gage "stove pipe". Remember, with DC, you have negative pressure which is the opposite of HVAC applications.

    I need to get some snap lock for my new shop. Where are you sourcing 26GA pipe and long radius elbows, and blast gates? Can you get the 26GA at a HVAC supplier, and the other items online? If so recommendations. I have a 2HP Oneida (the classic white one from a few years back ~2002)

  15. #15
    Several years ago I bought a 10HP dust collector and without much research I used 30g snap lock for a relatively moderate length trunk line in my shop. This unit only collected dust for a small part of my shop. The d/c sucked the 30g 12” snap lock not quite flat but almost in more than a few areas. I decided to upgrade to 26g 12” snap lock and never had another problem. So if 26g snap lock works in a 12” diameter on a 10hp Neiderman dust collector I would say it would work for almost anything else.

    I should note that I am in the process of reworking my dust collection system to have my 10hp Neiderman dust collector collect at every one of my machines instead of having multiple dust collectors spread around the shop. I could use 26g snap lock but I plan to use 12” PVC irrigation pipe which I can source locally for $175 per 22ft. My issue with snap lock is that where the pipe goes into the fittings is not a smooth transition and that nasty lip inside the trunk line is prone to clogs and greatly reduces the performance of your system as a whole. For my new and revamped system I am using standard HVAC fittings that will slip over the 12” irrigation pipe. Even the crimped ends will slip over with a little work using a heat gun. Take this for what it’s worth but I would use pvc over snap lock any day of the week.

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