Dust collection system ducting question

[Michael Gibbons]

Is it best to maintain the largest diameter ducting as far as possible throughout the entire system? I'm looking at an Oneida Dust Gorilla cyclone which has an 8 inch inlet and seems from what I've heard to keep 8 inch pipe and only reduce at machines and fab larger machine ports if possible.

[Bob Michaels]

You can call Oneida, they have pretty good support. I had them design the duct system for my 700 sf shop and it works great.

[David Kumm]

What size impeller and motor and what machines will be connected? Might make sense to go 8" for a machine or two or around a bend and then reduce to 7". Oneida does that sort of thing for free I think but it is a delicate balance to keep the larger diameter to reduce static pressure but to reduce to keep the velocity above 3000 fpm. If the machines are big enough for 6" ports or have multiple smaller ports the needs are different than for small machines with 4" ports. Dave