J. Phil Thien's Projects

Okay, I'm circling in, so to speak) on my separator design, and am thinking of a tall separator (like the one Bulldog8 has built), with a rectangular inlet (like retired2's).

My question is whether the vertical angle of the inlet has any bearing on separation efficiency. It's my understanding of the postings here that the more rotations of air in the separation chamber, the better collection of fine particles; a tall separator allows more rotations. In that case, it makes sense to me that the best placement of the inlet port is right under the top lid of the separator, and parallel to the lid (horizontal). That way, the air flow, as I understand it, takes a shallow spiral path.

On the other hand, Bill Pentz makes a big deal about having an inlet to his cyclone plan that is angled downward, with the downward flow reinforced by an internal air ramp. The air flow takes a much steeper spiral flow.

I realize that a cyclone with a cone is not directly comparable to a Thien separator, but does angling airflow downward, as Pentz recommends, make any sense in a Thein baffle separator? My sense is that while it might improve air flow through the separator, separation efficiency, esp. fine particles, would suffer, so I'm leaning toward going with a horizontal inlet. Any thoughts?

I'm in the process of planning/designing a top hat separator, and have found all the information on this site very helpful, esp. retired2's detailed assembly documentation.

I have a couple of questions:
1. I assume that a rectangular inlet is preferred, in that it provides for better laminar flow as air circulates in the separator. Also, the cross sectional area of the rectangle should be no less than that of the entering hose, to prevent air flow restriction.

That being the case, is there an optimal height to width ratio of the inlet? It seems to me that the narrower (and higher) rectangle would result in better laminar flow. So, for example, a 2 inch wide, 12 inch tall inlet would provide better laminar flow than a 4 by 6 inch inlet, and a 1 by 24 inch would be even better. Are there diminishing returns as the separator volume increases (to account for the taller rectangle)? This is all theoretical, since building 12 or 24 inch tall separator would get pretty involved. My gut instinct is to go with what appear to be practical dimensions (a la retired2's design).

2. I've been thinking about how to support the baffle, and rather than using threaded rods, I thought I might try using a couple of thin strips (3/8" to 1/2" wide) of sheet metal, hung from the top of the separator, with a right angle bend at the bottom of each strip to support the baffle. The wide dimension of the strip would be parallel to air flow, so I figure that it would produce less turbulence than a rod, but haven't seen anybody trying that. Any reason why it wouldn't work?

This is a great site with terrific information- all feedback will be appreciated!