DC piping at Cyclone inlet

[Eric DeSilva]

After seeing too many Creeker pictures of nice, organized DC piping, I'm toying with the idea of revising my current set up, which I lovingly refer to as the Frankenpipe. I've got a JDS Cyclone in the corner of the shop that has an 8" inlet, but also included adapters to go to 6" or even 4". After playing with the spreadsheet on Pentz's site, I think I'm going to stick with 6" S&D for the most part. Here are my two questions...

First, what are the recommended practices right at the inlet of the DC? I seem to recall hearing someone say that having a section of straight pipe at the inlet was beneficial. Is that true? If so, how big a section of 6" pipe is reasonable?

Second, right off the bat, I've gotta traverse about 7' down a wall and go up 5' to the ceiling, then come straight away from the wall across the room. I can do 2' of straight pipe, a 45* bend, about 7' of straight pipe diagonally, then a 90* bend to shoot straight off the wall. A 7' section of pipe diagonally across the wall chews up valuable wall space, however. The alternative is 2' of straight pipe, a 90* bend up the wall, 5' of pipe up the wall, another 90* bend to go across the wall, another 5' of straight pipe, then a final 90* bend to come out from the wall. I ran Pentz's spreadsheet just on the two scenarios and the loss in inches was less than 1/2" of SP. I'm thinking the gain in wall space is worth it. Anyone care to correct me?

The final alternative would be putting the first 90* turn right off the bat, and then using 7' of straight pipe across the wall. That recovers even more wall space, but means there is a 90* bend right before the DC inlet.

[Chris Padilla]

As to the long piece heading into the DC, make it as long as you can. If you can only do a foot, do a foot and don't sweat it.

Heck, I have about a foot of flex at my DC inlet becaue it made my life easier PLUS it also helps to isolate the "air raid siren" just a bit more although I already hung the whole beast on vibration hangers.

I made all my 90s putting together 2 45s to make them a longer radius bend. When I purchased my S&D fittings, two 45s were half the cost of the long-radiused 90.

As to how to route it, do what will work for you. I agree with you...1/2" gain ain't worth it...route it more efficiently for your space requirements.

[Terry Hatfield]

Agree with Chirs. I think in most instances we make WAY to big of a production out of this whole DC/ducts thing with nit picking every little detail. Now, with that being said, as much straight pipe right at the inlet as you can get will improve performance by causing the air to move more smoothly into the cyclone itself. Fittings and bends right before the cyclone cause the air to be very turbulent and that reduces effeciency and seperation. Straighter is better is the bottom line. 3' of straight pipe would be nice. 1' will do....or you could always have a chunk of flex like Chris. :eek: I would not do the 90 right at the inlet if there is any way around it.

For what it's worth.....

t

[Bob Borzelleri]

I agree. I needed to make a turn about 3 feet out and then again a few feet later. It's all in a run of 7". Whatever effect the two turns have, the drops still want to suck my arm up.

I should point out that both of my turns are 45 degree long radius fittings. I think the long radius stuff make a bigger difference that many folks think.

[Chris Padilla]

Actually, my DC inlet has a "built-in" 3' section as it goes from 6" round to a rectangular shope into the cyclone body. To that I have about a foot of flex...it was just WAY easier to connect it to my ducts.... :)

[Leo Graywacz]

If you have an 8" inlet then you should have a 8" duct connected to it. Don't downsize it right at the input. You will suffocate the cyclone, plus the air will be sped up as it enters the cyclone when it should be slowed down at that point.

[glenn bradley]

I'm with Chris as well. Here's a shot of my first few feet during the original build out. I had to get out, around the filter canister, leave access to the breaker panel then angle over to the wall and down to run to the TS, RT and BS areas. This machine has a 7" inlet. A 6" coupler fit snugly inside the inlet. I just ran a bead of silicone rubber around the "step" where the green stops and the plastic starts.

144515

The single strap to the ceiling and a couple strap pint once it hit the wall adequately support that entire section. have since added an additional wye to an overhead run but you can see the snaking around that is sometimes required. Avoid 90's whenever possible. It took some head scratching but I have done the whole shop with any 90's.

[Eric DeSilva]

If you have an 8" inlet then you should have a 8" duct connected to it. Don't downsize it right at the input. You will suffocate the cyclone, plus the air will be sped up as it enters the cyclone when it should be slowed down at that point.

Since JDS provided both an 8" and 4" inlet, I can't believe that 6" is going to be a problem. As much as I'd like to run 8" everywhere, I can't find S&D at 8". So 6" is what it is gonna be...

[Eric DeSilva]

Thanks all. I suppose it is kind of pointless to get too nitpicky about things. It will have bends, they all do...

[Leo Graywacz]

Since JDS provided both an 8" and 4" inlet, I can't believe that 6" is going to be a problem. As much as I'd like to run 8" everywhere, I can't find S&D at 8". So 6" is what it is gonna be...

Not saying you should have a large section of 8". Just the first section at the cyclone. It will slow the air down as it gets to the cyclone and provide better separation.

[Eric DeSilva]

Not saying you should have a large section of 8". Just the first section at the cyclone. It will slow the air down as it gets to the cyclone and provide better separation.

What kind of length are we talking about to allow things to settle down to a slower velocity?

[Leo Graywacz]

5 feet should help.

[Jeff Sudmeier]

I piped my cyclone with 3 elbows coming right off of it. I'm sure it didn't help my air flow but it's what I had to do.

As it is the new cyclone seems like it's pulling 3 times the air as my old collector so I'm not too worried.

Do what works for you, it will suck like crazy any way that you do it.

[Chris Padilla]

What kind of length are we talking about to allow things to settle down to a slower velocity?

If you're really worried, make a longish transition from 8" diameter to 6" diameter.

Here is a thread (http://www.sawmillcreek.org/showthread.php?t=9933) where I built my DC...it is worth a go through and there are some good posts there that show how to build transitions.

[Steven Harris]

I am new to SMC so if I am doing this wrong please forgive me. I have a 2 hp JDS cyclone DC and I am setting up a new shop. It also has a 8" and 2 - 4" inlets. Did you go with the 6" and if so where did you get the reducers and piping? Did you put it together with screws and aluminum tape? If not what did you use. Any help will be appreciated.

[Jim Andrew]

Steven, the S&D the guys are talking about is sewer and drain pipe, a thin wall plastic available in 4 and 6". If you are considering metal pipe, do not use the 30 gauge pipe you can buy at the big box stores, as it has suction on it and can collapse. Much better to use 24 gauge pipe and fittings. And yes, a few screws and aluminum tape hold metal fine.

[Darcy Forman]

You might be hard pressed to notice the difference on a dust collector. However evry prime mover benifits greatly from a straight inlet. Dust collectors are no different. I put a 8" six foot straight section into my collector. I've had my collector two years and never had anything carry over to the filter. The bottom filter cover looks as clean as the day I bought it. During this time I have emptied the dust barrel 50 to 60 times, and I have the big drum.

[Alan Schaffter]

If you look on Bill's site you'll find the inlet should be straight to reduce inlet air turbulence and improve separation. I may be wrong but I believe a rule of thumb is 5 X the pipe inside diam. 6" pipe would require a 30" straight section- minimum, longer is better.

Don't be too cavalier about the number of bends and impact on SP- a 1/2" here and a 1/2" there adds up really quickly, especially when you are only starting with 8" or 9" or less to begin with!

I'm not sure where the idea the air should slow down as it gets to the cyclone came from but the just the opposite is true- you don't want it to slow down, you want high velocity in the cyclone- the dust separates to inside surface of the cyclone by centrifugal force, so yes, velocity is important in a cyclone. The air will slow down on its own inside the cyclone due to the increased volume.

[Eric DeSilva]

It was so long ago I'm not sure what I used! I think for the 8" to 6" transition I used a piece of steel duct from Home Depot--I'll look tonight. If I recall, it wasn't a perfect fit, so I did wrap it with foil tape. I mainly used 6" PVC S&D pipe--I dropped it down to 4" for some machines, but as close to the dust-generating machine as I could get. I had a bunch of snaplock before--the frankenpipe--but the PVC is a lot easier to route neatly, and I think it loses less to leakage. I used plastic ABS blast gates that I thought were from Oneida Air, but I don't see them on their site anymore...

[Jim Neeley]

FWIW, I had a discussion with Bill Pentz regarding design for the the inlet to my Clearvue. He indicated that I should try to install 6' of pipe the same diameter as the inlet to his cyclone in order to ensure fully developed flow. An ell, wye or 45 causes the heavier pieces to move to the outside wall of the bend but 6' will allow it to recover.

An additional point: in my initial design I had 3'+ available, after which I'd need a 90* ell. I'd heard that two 45* ells were better (less stratification), so asked him if I'd be better with a shorter straight and two close 45's. He indicated that the straight pipe on the inlet was more significant as it increases the fines removal in the cyclone.

Based on that, if it was me, I'd go with 8" for the last straight run and neck down from there, if I wanted to maximize the fines collection.

Just my $0.02.. YMMV.

Jim

[Michael W. Clark]

If an elbow is required, the main thing is not to install one that is counter-current to the rotation of the cyclone. Straight duct is better.
Mike