Size Ratios?

[airoff]

Hello Phil,

Love the design for the separator - I think you have a marketable idea.  Even better that you chose to share it in this way.

I've been considering some variations on the components, and wonder if you would comment on some questions.

a) Have you found any relationship between the shop vac power and the size of the separator can?  Besides the fact that hp is a useless measure of vac power, there must be some point where the vac is too small for the can.  My limited understanding is that amps is more reliable than hp in judging power. Here's an interesting reference http://users.goldengate.net/~kbrady/motors.pdf

b) Similarly, is there a relationship between the shape of the can and efficiency?  One thought I had is using a sonnet tube (for round concrete forms) - they're strong, cheap, and can be cut to any desired height - 12"x48" = $8.  For example, does a tall, 12" diameter tube work differently than maybe a 24" x 24" garbage can?

c) Have you noticed any difference in the baffle material or thickness?  Maybe thin metal, or very stiff cardboard?

Thanks - getting ready to build my first one, and will share any variations I come up with.  And thanks to all that have contributed to this discussion.  I hope I have ideas that pay back some that I stole from you!! ;D

Alan

[phil (admin)]

Hi!  Thanks for the kind words.

(a) Yes.  But most times it doesn't matter.  The separator lid I built works great w/ 10 or 12-gallon and larger shop vacs.  But there are two rules for ANY cyclone:  (1) Don't stuff or overfeed them (stuffing too much debris down their throats reduces separation efficiency).  (2) Don't starve them (they need adequate airflow to separate efficiently).  So I wouldn't use a small shop vac with a 1-1/4" hose.  But pretty much any larger shop vac is fine.

(b) A 12" Sonotube would work fine, but the trick becomes the fittings.  You need to have room for a centered outlet plus the inlet fitting.  The fitting I use from Rockler/Woodcraft, for example, wouldn't fit.  But you could run PVC directly through the top, for example.

(c) The best baffles are thin, stiff, and slick.  Tempered hardboard has worked well for me.  But steel would work, and some have even used MDF.  But the more slick, the better.