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Thread: Snap lock versus spiral duct

  1. #1

    Snap lock versus spiral duct

    I am curious as to how you guys feel about the differences between spiral duct versus snap lock duct for dust collection purposes? With out considering the strength against collapse, but rather the performance characteristics only. I have a 5HP Grizzly double bag with a 6” inlet for the back part of my shop which will provide dust collection for 6 machines in a roughly 25ft x 25ft area. I use a larger 10hp unit with a 12” inlet for the main part of my shop. The main part of my shop that uses my 10hp unit is already plumbed and good. For purposes of this thread, it is my 5HP Grizzly that I am trying to consider spiral duct versus snap lock.

    Assuming that the connection points between the individual sections of snap lock and the associated fittings are positioned where the direction of air flow will not snag on the lip of the mating piece, and assuming that the duct will not collapse, is snap lock that much of a down grade from spiral?

    I wonder if the crimped ends of the snap lock could be cut off and the proper male and/or female spiral duct connectors could be use to join them together, thus eliminating the lip inside the duct system? Or if one could use spiral duct pipe and snap lock fittings by trimming off the crimped ends and using male or female spiral duct connectors?

  2. #2
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    Even though I'm moving to clamp-together duct for the new shop, given the choice between spiral and snap lock, I'd pick spiral after having used snap lock for many years. It's a better solution all around, IMHO, and designed for the purpose. Snap lock is pretty much "designed" for HVAC and old-school stove pipe applications and the whole crimp setup introduces more interference with air flow for dust collection purposes. That's not significant for small setups for sure, but in your case, based on previous threads and postings, you need the beef.
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  3. #3
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    If money were no object I'd certainly have the spiral, but alas...

    That said, in my 30x30 ft shop with a 7" main line that picks up 4 and 5" drops the snap lock stuff works fine. I have a much heavier gauge than is used for HVAC work and I've sealed all the joints. Might the spiral be more efficient? Probably. Could I tell the difference? Probably not. The chips end up in the bin with no discernible problems.

    OTOH, going from a bag to a HEPA canister filter made a huge improvement in both air flow and air quality.

  4. #4
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    I used 26 ga spiral, 8", 6" and 4". It's very sturdy. They make it with the bumps on the seams on the inside or the outside. You want the stuff with the bumps on the outside and smooth on the inside. It is just insignificantly more expensive than the other.

    I have a few places where the fittings fit with the crimps facing the 'wrong way', but there's never been anything get caught up there and the fit is pretty tight. I can't imagine that it causes much airflow loss.
    Last edited by Frank Pratt; 05-22-2022 at 2:58 PM.

  5. #5
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    Perfectly happy with my snaplock, 26 gauge in sizes up to 7". Cost no issue? Then upgrade to spiral. Enlighten me, snap lock is smooth bore with a seam in line with the flow. How can spiral (excluding the joints), be better? Looks cool, but not as clean as snap lock.
    Attached Images Attached Images
    NOW you tell me...

  6. #6
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    Quote Originally Posted by Ole Anderson View Post
    Perfectly happy with my snaplock, 26 gauge in sizes up to 7". Cost no issue? Then upgrade to spiral. Enlighten me, snap lock is smooth bore with a seam in line with the flow. How can spiral (excluding the joints), be better? Looks cool, but not as clean as snap lock.
    The spiral is much stiffer for a given gauge. I could have easily used 30 gauge without danger of collapse, but nobody carries it.

  7. #7
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    Quote Originally Posted by Frank Pratt View Post
    The spiral is much stiffer for a given gauge. I could have easily used 30 gauge without danger of collapse, but nobody carries it.
    When I was looking HD carried the 30 ga stuff, but the only pics I have seen (on this site 10 years ago) of collapsed duct were of 30 gauge snap lock. Or are you speaking of 30 gauge spiral?
    NOW you tell me...

  8. #8
    Quote Originally Posted by Ole Anderson View Post
    When I was looking HD carried the 30 ga stuff, but the only pics I have seen (on this site 10 years ago) of collapsed duct were of 30 gauge snap lock. Or are you speaking of 30 gauge spiral?
    I originally used 12” snap lock on my main dust collector which is a large 10hp 3 bag unit and it collapsed it first time I used it. Now my smaller 5HP Grizzly double bagger has used 6” snap lock no problem with out collapsing the duct at all. I am just curious how the performance aspect differs between snap lock and spiral duct.

  9. #9
    Another option is to go PVC which is what I am leaning towards. I can get 30ft long sections of 6” PVC for a Benjamin. Elbows are under $20 and wye’s are like $50.

  10. #10
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    I gutted out all my spiral and went clamp together. I found Spiral okay but not easy to work with. Clamp together is fantastic.

  11. #11
    Quote Originally Posted by Bobby Robbinett View Post
    Another option is to go PVC which is what I am leaning towards. I can get 30ft long sections of 6” PVC for a Benjamin. Elbows are under $20 and wye’s are like $50.
    I was going to ask if PVC was an option.

    I used 6" Charlotte PVC (because that's what Lowes sold) with my 3HP Onieda and so far, so good.

  12. #12
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    I would avoid PVC like the plague. I tried using it for 2 years and dislike almost everything about it. Plus it currently isn't any cheaper than quick-clamp, at least around here. I highly recommend neither spiral nor snaplock nor PVC, but instead quick-clamp.
    Last edited by Jonathan Jung; 05-31-2022 at 2:17 PM.
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  13. #13
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    Quick clamp is way higher cost than spiral. It is nice, but except for the minor convenience during installation, performs no better

  14. #14
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    I used spiral in my shop (20x30) and would do it again. 7" inlet, with 6" drops. Easy to cut with a jigsaw and rivet or screw together and tape the seams. Moved a couple sections and it was easy to disassemble.

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