# types of ducting needed for DC



## mikeyr (Sep 3, 2015)

Ok, so I bought a used Oneida Dust Gorilla, its a older unit, 3HP with a 8" inlet and I ducted it to my tools using Home Depot sheet metal ducting.

I come of out of the DC with 8" pipe about 4ft long, then I Y that 8" to 6" (8-6-6), the first 6 I made a sharp 90" and a reduction to 5" for my blast gates that came with the DC and then to 4" for about 15ft of flexible hose to attach to various tools. I know, this is not at all optimal but its a garage that is sometimes a workshop and I seem to have plenty of air movement for my tools.


The next section of 6" piping goes around the corner using 2 45's to get a long 90 and then about 12ft., another long 90" 5ft down to a blast gate and about 6ft. of flex line for the table saw.


I did this over the holidays and worked with it for 4 days without any issues and no visible dust in the air even when using my 16/32 drum sander, super happy. When Santa was done with the project I (Because I am Santa) disconnected the hose at the table saw to clean up the floor (I did a lot of trimming/edge cuts without saw guard so there was some mess) and within the first minute the hose sucked to the floor and boom, the long straight section of pipe collapsed, I assume that would have happened if I started the DC with a blast gate closed also but I didn't.


I had read that this can happen with cheap ducting but I thought I would be ok. Do I really need to spend the money and buy spiral ducting ? or equivalent ? The HD stuff was cheap enough that if I have to throw it away, I am ok with that. Its more the work that was involved that I don't want to redo. I was thinking of getting better ducting for the straight sections but leave the Y and the 90's alone, they didn't collapse or is it a case that if I get the better ducting the 90's might collapse next ? 



I didn't seem to have any issues with the 6" suction, so can I stay with the 6" for the longer run or should I go to 8", I didn't go to 8" because that meant removing the TV from the wall and building it out away from the wall and I was able to squeeze the 6" behind it, if I have to redo it now that I am not in a hurry, maybe I should do that and go to 8". My absolute longest run will be 9ft from the DC to the corner, 12ft. over the door, 5ft. down to blast gate. I rushed way too much this first time, now I have to do it again.


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## CharleyL (Jan 13, 2019)

Your ducting is most likely made from 30 gauge galvanized steel, which is what is commonly used for furnace and HVAC ducting. A 3 hp dust collector has the ability to violently collapse that ducting as soon as you run the dust collector and restrict the air flow through the duct to it. Most home shop dust collection systems go with 26 gauge spiral pipe, 26 gauge straight pipe, or large diameter PVC pipe. For the PVC, you don't need the DWV class. You can get away with irrigation pipe, which is considerably thinner, and cheaper, but finding PVC irrigation pipe and fittings is sometimes difficult in sizes larger than 4" diameter. 

Charley


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