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Posted on Disappointed with my Onieda Super Dust deputy

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EarlS

4446 posts in 3426 days


#1 posted 06-26-2018 05:12 PM

From Wiki -

A high speed rotating (air)flow is established within a cylindrical or conical container called a cyclone. Air flows in a helical pattern, beginning at the top (wide end) of the cyclone and ending at the bottom (narrow) end before exiting the cyclone in a straight stream through the center of the cyclone and out the top. Larger (denser) particles in the rotating stream have too much inertia to follow the tight curve of the stream, and thus strike the outside wall, then fall to the bottom of the cyclone where they can be removed. In a conical system, as the rotating flow moves towards the narrow end of the cyclone, the rotational radius of the stream is reduced, thus separating smaller and smaller particles. The cyclone geometry, together with volumetric flow rate, defines the cut point of the cyclone. This is the size of particle that will be removed from the stream with a 50% efficiency. Particles larger than the cut point will be removed with a greater efficiency, and smaller particles with a lower efficiency as they separate with more difficulty or can be subject to re-entrainment when the air vortex reverses direction to move in direction of the outlet.

For anyone that is interested in the theory and math, there is a section that goes into the math of cyclonic separation.

So what does this mean? Others have suggested you need some back pressure. Why? That will force the system to a lower flow rate since the blower curve goes from lower flow and higher differential pressure to higher flow and low differential pressure. Why does this matter? Low differential pressure and high flow means higher velocity which means more of the dust is being held up in the airstream rather than hitting the walls of the cyclone and falling out. It’s all about dissipating energy and slowing the particles down in the cyclone so they fall out of the air stream.

The go to source is Bill Pentz, if you have time to read through his site.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"


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