6" can topper - advisability of temporary reduction to 4"

[SteveSawyer]

I'm building a separator topper for the top of a 30-gal plastic drum, almost identical to VAWoodworker's design as seen in this thread.. About the only change I'm making to VAWoodworker's design is to use 1/8" UHMW to line the inside of the separator ring instead of hardboard.

My current collection setup is powered by the ubiquitous HF 2HP (yeah, right) dust collector. I have a larger blower with a 12" impeller that I plan on fitting to this separator once I can find a good used 2-3HP motor for it. In the meantime, I'd like to use the motor and blower from the HF unit and use the existing 4" ducting.

My question is, how much do you think the efficiency of the separator would be compromised if I temporarily fit an adapter to the 6 1/4" inlet of this separator to allow it to connect to my current 4" ducting? Would it make a difference if I placed the 4" port at the bottom of the 6" port (closer to the drop slot)?

Thanks.

[gregascull]

I built mine based on this same design and until I got my 6" piping hooked up I used a 6->4" PVC adapter directly on the unit.   That way I didnt have to fix the opening in the unit once my pipe was ready.

It worked really nice as a stop gap.

[SteveSawyer]

Okay - thanks for the tip, Greg.