Originally Posted by
Michael W. Clark
Mike, Sorry for the short response above. As you know a cyclone operates on an efficiency curve, it captures a higher percentage of larger particles and a lower percentage of smaller particles. We have had cyclones that caught the fines but allowed larger chips to bypass. The first thing you check is that the cyclone is sealed at the dust discharge.
After that, if the problem still persists, you look at the inlet arrangement to see if the ducting could be an issue (causing turbulence as the air enters the cyclone). Sometimes, this is not easily improved. The main thing is that you do not have elbows causing the air to turn counter-current to the cyclone (as viewed from above). Ideally, you want about 6 straight duct diameters at the cyclone inlet.
If the problem still persists, the next thing to check is the interior of the cyclone. If the curved surfaces are not smooth (large weld gaps, not enough breaks on the curved parts, mis-alignment between body and cone creating a ledge, build up, dents from users trying to free plugs, etc), the large particles will hit these places as they spin around and get thrown back into clean gas vortex and go out the top.
Since you have changed cyclones and getting both fines and chips over to the filters, I suspect it may be related to the cyclone efficiency itself. If this is the shorter Laguna model compared to the Oneida unit, the Oneida unit may be more efficient. Cyclone efficiency is not just about pressure drop, but about proportions and size as well (the last two has a much larger effect on fines).
Hope this helps,
Mike