6” or 7” ducting?

[Juss1]

Finally finished my electrical and getting ready to buy ducting for my new to me DC. It’s a 3hp with a 8” port (currently split to 2 4”). Went back and forth in the material but finally settled in 26 awg metal ducting. PVC is just way too expensive at the larger sizes. My question is should I go with 6 or 7 inch main line?

[cpolubin]

I put in a 3hp Oneida V-3000 last fall and had Oneida go over my ductwork drawings. They had me use 7" duct for the main run, 6" for the branches and stepping down to 4" or 5" as needed in short runs at the end.

I used 26 gauge snap lock. I'm 70 and was installing it alone so wanted the lightest pipe I could get. Get a good set of snips and a good crimper and you can make everything fit perfectly.

Cliff

[Juss1]

Thank you! That’s very helpful information. I had initially planned on going 7” throughout the whole run till the very end.

Anyone have recommendations on a crimper?

[cpolubin]

This one is good.

https://www.amazon.com/gp/product/B005ZD...UTF8&psc=1

Cliff

[Cabinet Monkey]

You should likely be using 8" for the main trunk line. That's the size of your inlet.

[Juss1]

That’s the other thing I wondered about. I emailed laguna (I have a pflux 3hp) but they said they were not allowed to advise on ducting. Which seemed strange. A lot of the ducting info I’ve read said either 6 or 7” which is why I thought 7” was the right decision. Any help on this is appreciated. Thanks

[fredhargis]

You can over size your trunk line if you stick with the puny ports many tools have. While you might have a 7" truck, if it's hooked to a 4" port, that's all the air you will move. That amount of air may (will) be insufficient to keep the chips/duct suspended in the larger duct which results in clogs. 8" will be even worse.  I would suggest a 6" main trunk, and run 6" as far as it will go...to the point of modifying the tool's ports to take a 6" in every case possible. (and it won't be always possible). With a 3 HP dc, 6" would be plenty anyway.

[Cabinet Monkey]

That’s the other thing I wondered about.  I emailed laguna (I have a pflux 3hp) but they said they were not allowed to advise on ducting. Which seemed strange.  A lot of the ducting info I’ve read said either 6 or 7” which is why I thought 7” was the right decision. Any help on this is appreciated.  Thanks

You can over size your trunk line if you stick with the puny ports many tools have. While you might have a 7" truck, if it's hooked to a 4" port, that's all the air you will move. That amount of air may (will) be insufficient to keep the chips/duct suspended in the larger duct which results in clogs. 8" will be even worse.  I would suggest a 6" main trunk, and run 6" as far as it will go...to the point of modifying the tool's ports to take a 6" in every case possible. (and it won't be always possible). With a 3 HP dc, 6" would be plenty anyway.

And some systems only support 4” ducts.  Y’all gonna go with that ?

Look, it only matters what your dust collector will support and how large your pipe network is.  While the tool’s port size at the end of the run is important , it’s not the main focus point for sizing your main trunk line.  You can always have several 4” ports open at one time to maintAin velocity, if you’re worried.

Another thing you guys seem to be overlooking is that designers basically tell you what size main duct to use by their choice of inlet. If the machine has an 8” inlet……………….

[MstrCarpenter]

When it comes to joining the branches to the main, this may help;
https://www.blocklayer.com/pipe-miter

[fredhargis]

And some systems only support 4” ducts.  Y’all gonna go with that ?

Look, it only matters what your dust collector will support and how large your pipe network is.  While the tool’s port size at the end of the run is important , it’s not the main focus point for sizing your main trunk line.  You can always have several 4” ports open at one time to maintAin velocity, if you’re worried.

Another thing you guys seem to be overlooking is that designers basically tell you what size main duct to use by their choice of inlet. If the machine has an 8” inlet……………….

Believe what you want, nio skin off my nose. But that 8" port was put there by the same guys who claim it moves 2700+ CFM. Nuff said.