Pipe size for DC separator

[Rob Cunningham]

I posted this on Phil Thien's site and thought I'd try here also.

I'm in the process of making a separator using a Phil Thien baffle. My dust collector is a Penn State Industries DC-4, 3 hp, 1900cfm free air (so they claim ) There is an 8" inlet on the dc. I'm planning to run 6" pipe from the separator to my machines. I am going to use a side inlet into the barrel .
Should I use 8" pipe between the dc and the separator or reduce it to 6"? Also, how much distance should there be between the pipe coming into the top of the separator and the baffle?
Thanks for any help.

Rob

[Sonny Edmonds]

You better have a really big barrel.

[Leo Graywacz]

8" to the collector

[Rob Cunningham]

Thanks Leo. That what Phil said also.
Sonny, it's actually 2 - 35 gal drums. One for the separator and a lower one to catch the chips. Kinda like a cyclone setup.

[Leo Graywacz]

The last section of piping in the DC should be a larger diameter so the chip flow through the pipe slows down. When you have the piping at your machine you want it to have an airflow rate around 4000 FPM. This keeps the chips suspended in the airflow and prevents chips falling out and coming to rest in the ductwork.

On my setup, which is a cyclone, I have a 7" inlet, so I have a 7" ductwork as the main trunk until I have some down feeds as soon as I start having down feeds I reduce the trunk to 6". Off of the down feeds I have 5" feeds to the machines. These are short and generally less than 6'. After the blast gate I have a short section of 5" flex tubing. The last machine in the line is my jointer so I reduced the ductwork to 5". All of this is to keep the speed at approx 4000 FPM and to have about 650 CFM at the machine. Generally I run 1 or 2 machines at a time. When I use the planer I shut all gates except the planer.

You have probably seen my setup, but here it is again.

[Rob Cunningham]

Leo,
Thanks for the info and the picture. It gives me a little more understanding of what I need to do.
Rob

[Phil Thien]

Nice shop Leo. I like the "faux taped but unpainted drywall" finish. I'm going to use that, too.