Overkill DC?

[Rob Will]

I just purchased a used Oneida 7.5 hp belt driven fan and cyclone system to install in the new shop. The cyclone is 28" in diameter and has a 10" inlet.

The duct layout will be an 8" pipe on one side of the shop and a 6" pipe on the other. These two lines will come together about 8' before the cyclone.

Here's the problem: This DC is a little too big for a one man shop and I'm worried about maintaining enough air velocity / volume to keep the cyclone working properly.

How many CFM are required to get a 28" cyclone going?
Any thoughts on how to monitor this?

Rob

[Dave Harker]

I think the 7.5 hp motor will do a fine job at "maintaining enough air velocity / volume" as long as you have large enough ducts for the air to move through. Be sure to use 6" connections at each tool, you can replace the factory supplied 4" connections (typically used on table saws, etc) with 6" HVAC fittings - furnance vents.

The link below shows what I did for my benchtop planer - 6" HVAC fitting.
I've done similar "ugly but functional" mods to other tools.

http://webpages.charter.net/harkerho.../dcplaner.html

[Rob Will]

Come on guys, surely somebody knows how many CFM is required to get a 28" cyclone "spinning" at an effective level. (???)

Rob

[glenn bradley]

"I'm worried about maintaining enough air velocity / volume to keep the cyclone working properly."

I may be missing the concern. The unit is designed to move enough air for it's size. If you're concerned that just having one 6" leg open will be too restrictive, I wouldn't be concerned. The unit works hardest in a free air condition. Any restrictions will not cause damage and the static pressure should move the dust.

Ahhh, wait. Are you concerned about air speed? Hit Bill Pentz' site. He has more data than you could need. I run a little Delta AP-400 1HP with a 4" hose and have plenty of air motion. It easily picks up dust from the table surface at about 6" away. You're machine will be moving vastly more air than that.

[Jim Becker]

Rob...you can get the specific answer to your question by speaking with or emailing the folks at Oneida. It's their system design and they can tell you how to best implement it in your shop. I suspect you'll be in the enviable situation of being able to have multiple gates open, too...and kick-butt collection from "hard to collect from" tools.

[Rob Will]

I'm trying to figure out how much airflow (CFM) is required to keep my 28" cyclone separating at an acceptable level.

Bill's website only states: " These larger diameters kill the fine dust separation efficiency putting even more stuff into the filters."

Hopefully Oneida can put a specific number on this.

Thanks,
Rob

[Rick de Roque]

I'm trying to figure out how much airflow (CFM) is required to keep my 28" cyclone separating at an acceptable level.

Bill's website only states: " These larger diameters kill the fine dust separation efficiency putting even more stuff into the filters."

Hopefully Oneida can put a specific number on this.

Thanks,
Rob

A 7.5 HP D/C will have no problem with air flow with even 2 or 3 gaits open (6" duct work). I believe Bill's site is talking about D/C's with 1-3 HP motors.

Rick

[Chris Rosenberger]

I have a 7 1/2hp Aget dust collector with a 12" inlet & a 12" outlet. I do not know the cfms it pulls. The number of open gates at one time are as follows.
5 - 4"
3 - 5"
1 - 6"

[Rob Will]

Thanks guys,
I know the 7.5 hp dc has plenty of power. Actually, I figure that it will require a couple of gates to be left open so that the cyclone has enough air velocity to separate properly. Remember that this particular cyclone is 28" in diameter. Low airflow will cause the cyclone to be lazy and send all the fine stuff right into the filters.

How about this: Does anyone know of where to buy automatic vents that can sense high static pressure and allow some air into the end of each run?

Rob