Quote Originally Posted by Phil Thien View Post
So if you work your #'s backwards to try to compute the pressure loss of a conventional cyclone (by subtracting the values I've highlighted in red because a conventional cyclone doesn't use them), you arrive at a pressure loss of 1.0 VH? .....

And considering that many users build my separator using tangential inlets, or (even easier) modify the rings of their DC w/ a baffle, it isn't unreasonable to think that the pressure loss of baffle-based separators may well be lower than most conventional cyclones.
Phil, I love your baffle idea and have installed two different versions. For an existing dust collector, I don't see why the Thien baffle would add any pressure drop to the overall system. It is a wonderfully simple method of improving dust collection in a commonly used piece of equipment.

My point is that adding a separate trashcan separator in front of an existing DC adds lots of pressure drop. Adding a cyclone in front of an existing DC would also increase the pressure drop. If a separator and cyclone had similar dimensions and similar configuration, then they should have similar pressure drops. But the low cost, low tech reality of trash can separators is that we use 4" PVC pipe and 45 degree elbows.

My main belief is that plugged dust bags or canister filter are a major source of pressure drop and flow reduction. And that either a cheap cyclone or separator is an improvement over a plugged up canister. I have a Jet canister to sell if anyone is unconvinced.