Input on dust collection duct design

[Jeff Creaton]

Looking for input on duct design for a dust collection system. I’m moving my shop from a 400ft2 shared car garage & workshop space to a dedicated workshop space with approx 600 ft2. All of my equipment is on wheels so all easy to move around, and a few pieces like lathe I have not purchased yet so are placeholders for the future. My dust collector is a HF mod with Thien baffle (cyclone separator) with a 6” inlet and ducting is 6” sewer and drain PVC.

I've sketched out my 3 top ideas right now, see below and I'm leaning towards option #2.

Look forward to your input!

[Carl Kona]

Jeff,

Option 2 looks to have the shortest runs, but are still significant. I estimate 7-9" of SP loss for the Thein, filters, ducting, flex hose, etc. The stock HF can only produce 7" max with the 10" impeller. Even with a 12" impeller upgrade you will still be maxing out the blower capabilities with typical 9-10" SP max. So you can install the 6" try it out and then upgrade to a single larger unit or like some have done get multiple units with shorter runs to one or two machines.

[Jim Becker]

Option two appears to be the most efficient for the majority of the drops.

[Jeff Creaton]

Thanks, Carl! I'll definitely report back how it works out. Good to know to about the 12" impeller upgrade mod, I'll have to look it up to see how easy it is to do.

[Bill Dufour]

All else being equal it is always a good idea to have the dust bin near a door to the outside. I actually cut a door opening into the wall right behind the dc. I can just barely sneak around the cone if the drum is gone. Makes it really easy to open the door, from the outside, and wheel the drum out to the garden for dumping the chips. There is a 2x4 and plywood across the opening about 5' and up to support the DC.
Easy to remove the dc and supports when we sell the house leaving another door into the building.
Bill D

[Rod Sheridan]

Hi Carl, option 2 looks best from a ducting perspective, however I agree with Carl, you don't have enough blower performance for an installation of that size.

regards, Rod.

[Jeff Creaton]

Couple of follow up questions... What are the key performance criteria I should be looking aiming for I my system (CFM, SP loss, etc?) How do I verify the performance of the system once installed, i.e. how to measure CFM and SP loss - is there a simple tool I can buy?

[Jim Becker]

Fan curves are your friend, Jeff. Unfortunately, many of the names that sell dust collection systems don't provide them while providing misleading information. Ideally, you want to maximize CFM (real CFM, not "paper" CFM) and that's going to require a larger system...something like Oneida's cyclones or a Clearvue, etc. Note that these are "long cone" cyclones and tend to separate and perform better than the "short cone" cyclones that seem to have become popular in the mass market. Once installed there are various measurement devices you can purchase and/or make, but if you get a good design and a good system up front, you may not actually need to go to that trouble and can spend your time working on projects. Talk to Oneida and/or Clearvue to get their input on what's appropriate for your machines and proposed duct work.

[Carl Kona]

Jeff,
As Jim said, the curve is your friend. You want to start at the machine furthest from your DC and add up all the pipe (and flex) resistance. There are many sights that provide pipe equivalent resistance for you to calculate manually. But it is easier to use Bill Pentz's SP calculator (it is an Excel spreadsheet you download) and just populate the sizes and lengths. It self populates other fields but you can get just the pipe resistance. Add 2.5-3" of SP for the Thein separator and another inch or two for a seasoned filter and you have a good start as two what you need to overcome. If that is 8" of SP look at your curve and see where your CFM should be. Since you have the HF, that curve is available here on page 68 http://www.portercable.com/uploads/P...Collectors.pdf However since you have modified the unit this curve does not exactly apply but will be a start. If you add the 12" Rikon blade you can expect performance about what the Rikon unit (60-200) provides on the same chart. Since the Rikon starts out on the right at about 3" of SP if you add the Thein 3" of SP you are already below suggested velocity levels for 5" duct.

To see what static pressure you actually have you can make a manometer (search for DIY builds, there are many). That only gives you SP, which is fine if you have a stock machine and a real fan curve for the unit. I started out with a small anemometer to measure velocity. Unfortunately those units are highly unreliable for actual numbers, but are great for verifying improvements to a setup. Check out RedOaks blog on that over in the LJ forum. To get actual test data you need a Pitot tube to measure velocity. I acquired one recently and compared it to my anemometer. My real air speed was 30% lower than the best number I could get from the anemometer. I bought my Pitot tube and Magnahelic gauge on ebay for about $55.

[Jim Finn]

I have a Grizzly 2 HP 240 volt dust collector. I ran a metal 6" duct to all my equipment. I avoided the long duct running up to the ceiling and then back down to each tool by positioning my tools along two walls and running the 6" duct along the wall at floor level. Then up a little to each tool. Works well for me.

[Anthony Whitesell]

Are #13 and #14 bandsaws? If so, how are you going to use them stuck in the corner as shown in option #2. I'm going to put forth the long 34ft run in options #1 and #3 will not be effective. What is going in the open area to the right (where the word 'option' is?

The fishbone plumbing method is touted as one of the more effective methods for keeping the duct runs short. To make the method more efficient the dust collector should be centralized. In options #1 and #3 the DC is in the upper left, in option #2 it is in the lower right. None are centered. The left wall appears to have a RAS or Mitersaw bench preventing the DC from being on the center of that wall. placing the DC to the left of the double door at the top or to either side of the single door at the bottom would be more centralized, and the duct runs would be even shorter.

Another option would be to have a small machine dedicated DC for the tools #134 and #14 in options #1 and #3, thus doing away with the long and expensive 34+ foot duct run.