Which DC baffle design works best?

[jmbchap]

[Original email to Phil, with minor edits to be more clear:]

I have been following the baffle design for a little while as I design my new
separator. I have looked at the Pentz design, but do not have the cash,
voltage, or headroom for that yet. Then I stumbled across your design...
just the ticket to start with! I have a few starter questions:

I am looking at Greg McCallister's design, but it seems quite
different from your original design. I saw in one posting that a main key to
your success is the instant pressure drop as the air hits the end of the
ridge and goes into the drop zone (instant expansion). Is this correct?
It would seem that Greg's design has the air losing speed above the
baffle, I believe approx 3.5 inches above the baffle. This would seem to
reduce the effictiveness of your design since you will not see such a
drastic pressure drop for losing particles. The other design I am following
is from VAWOODWORKER which seems simple, but does not follow the above cyclone
design.

If you could provide some feedback I would appreciate it. I am in the design
phases and have a ton of flexibility. I am going to use a 2HP HF DC and a 30
gallon trash can and 6" piping (unless the design changes!).

Thank you!

JMBCHAP

[Phil's Email Response:]
They're actually both the same.  The one using the DC ring just has a true
tangential inlet.  They both have a pressure drop as soon as the incoming
airstream leaves the inlet.

I'm not sure if I'm answering your question.  But if you have a follow-up do
me a favor and post it at the forum.  I'm getting nailed with work mail and
don't have as much time as I'd like for one-on-one E-Mail for the separator
stuff.

[Please quote my entire message in your reply to avoid our spam filters.
Thanks!]

[jmbchap]

Here is a follow up to Phil's response:

OK - I now understand that the main pressure drop is at the exit of the inlet inside the upper chamber (above the baffle) since that is the largest volume change. Is there any significant or additional pressure drop when the air passes over the end of the ring into the drop zone? It would seem to me that having an open baffle all the way around (360 degree drop zone instead of 240 degrees) would allow the debris to continue to drop and would allow for the separation between the dirty turbulence below and the clean exit air above. I am sure I am missing something (I have a few theories, but thought I would talk to the experts...).

My ultimate question is if the cyclone top design is more able to separate out finer dust since it would reduce turbulence in the upper chamber, or does that theory not hold and either design will result in the same approximate efficiency? Have any studies been done on this?

Finally, for the McCallister design... since the inlet is approximately 3 inches above the baffle, how would that affect the "clocking" of the baffle drop zone? Should I have the ridge start just below the exit of the inlet, or rotate it around to compensate for the downward swirl of the air and debris?

Thank you to all who help with my questions!

JMBCHAP

[Greg McCallister]

jmbchap,

I found that putting the end of the solid end of the baffle at the end of the inlet seemed to have the best results.
I noticed that Phil's design with a 2.25 inlet has it in the middle or towards the beginning.
However, when people went to 4" it was placed more towards the middle.
Hope that makes sense.