Question for the cyclone experts

[Ken Garlock]

I am assembling the Pentz cyclone which I bought as a kit from Clarke Echols.

The inlet to the cyclone from the collection duct is a sheet metal transition of about 24 inches, round on one end, square on the other to fit into the cyclone. That 24" inlet protrudes out considerably from the rest of the cyclone, and is giving me a problem as to how to route my PVC duct. I want to keep the duct as close to the the walls as possible, and I want that to occur on two adjacent walls. The cyclone would be in the corner with a duct branch going along the north wall, and another branch going along the east wall.

What I thought about is replacing the long inlet shoot with a short transition with a total length of 8 to 10 inches. This would provide me with more room to, in turn, put a pants-leg wye on the end of the transition followed by one or more 45s, etc. The actual implementation of the duct work is still under consideration.

With this drive-by background, the question boils down to this:

How critical is the the 24" cyclone inlet shoot, can it be shortened without making a major impact on the efficiency of the cyclone?

I have looked through Bill's site and didn't find anything about the shoot length, I probably over looked it :(

Comments :confused:

[Jim Becker]

I'm certainly not knowledgeable about that design, but I strongly suspect that the size, length, angle and design of the inlet is critical to the performance of this cyclone. Before you change it, talk to the designer(s).

[Ken Garlock]

I'm certainly not knowledgeable about that design, but I strongly suspect that the size, length, angle and design of the inlet is critical to the performance of this cyclone. Before you change it, talk to the designer(s).

Jim, you make some good points. My only problem is the length of the inlet shoot. Worst case, I will use the original design and make it work. I was hoping that someone here had additional information on the length issue. I wanted to try SMC before bothering the designers. :)

[Jim Becker]

The inlet of the cyclone is a pretty important thing as the design insures that the air flow enters the cylinder in an orderly and controlled fashion. Same for the tranistion from round to rectangular...too abrupt and it messes up the air flow. Don't worry about bothering the designers...that's what you paid the bucks for.

[Chris Padilla]

Ken,

Email Bill Pentz directly.

In the end, unless you hook it up both ways (unmodified and then modified), you will never know the difference...if any.

[Ken Garlock]

Ken,

Email Bill Pentz directly.

In the end, unless you hook it up both ways (unmodified and then modified), you will never know the difference...if any.

I most likely will have to just that. I hesitate to Email Bill because a couple weeks ago he announced that he was tired of maintaining his dust collection site, and that we would no longer answer any Emails. He now has a sponsor for his site, so I don't know if the Email embargo is still in force. :confused:

[Steve King]

Ken,
I am no expert but what I have read from Bill's site and others, you need a straight shot into the cyclone. The more curves and fittings before the inlet will cut down on the CFM.
I would contact Clarke Echold = mailto:clarke@verinet.net?subject=Re: Cyclones
Steve

[Steven Wilson]

I had a similar issue when working with Oneida on the inlet for my cyclone. They highly recommended a short (24" is about right) straight piece entering the cyclone and to go very gentle with the first turns; no back to back 90's, use a short piece between 90's, etc.

[Chris Padilla]

Just to reiterate what some of the other folks have said, the main inlet on the cyclone is pretty key to maintaining effiiciency and therefore you want as smooth a possible (low-turbulent) airflow in this area.

I guess you either need to try it both ways, Ken, or bite the bullet and not mess with the inlet. If you get lucky, Bill might see this post and help you out. Clarke is a great guy but I'm not sure he has the knowledge base Bill has to adequately answer your question any better than any of us.

Good luck to you...keep us posted! :D

[Ken Garlock]

I will first give Clarke an Email. I know he is busy with all the kits that people are ordering. If I don't hear from Clarke, I will try Bill. If I don't hear from either one, I will leave the shoot without modifications.

I do not plan to use any 90 deg elbows in the duct work. However, I sure would like to have one of those big long-radius 90s that Oneida uses to connect to their filter stack. :) I can see one pants-leg wye, a number of 45s and sanitary tees.

I will endeavor to persevere. :)

[Ken Garlock]

I Emailed Clarke Echols about 2:20 CDT, and he has already replied. The following is his response I wish to share with the forum:

"Ken,

The length of the transition tube allows any turbulence in the air stream
(such as coming out of a wye) to settle out so that it is a smooth laminar
flow with no turbulence as it enters into the cyclone itself. This
greatly improves separation of the micro-fine dust and is further enhanced
by the air ramp. Shortening the inlet transition runs the risk of
increasing turbulent air flow, allowing more fine dust to escape into the
blower, causing increased filter loading and shorter filter life. It's
important that the centerline radius through bends and fittings be not
less than 1.5 times the pipe diameter (9" radius for 6" pipe) to keep
static-pressure drops to a minimum.

So once again, as so often happens in the "real world", you've been
trapped, as have many, by the laws of nature. :-)

I'd avoid shortening the transition if possible. You could probably
shorten it by six inches at most, but the longer it is, the better it
works (within reason).

Clarke "

So my solution is to use the inlet shoot as designed and delivered. I will find a solution that will work in my situation.

Thanks for all your comments. :)