On Mar 6, 1:21 am, "trs80" wrote:
My DC has a 5" dia inlet opening to the impeller.
If I go with 6" main pipe for my small shop DC system, should I open up the
inlet on the DC to 6".? Or should I make the mains 5" dia?
thanks for any tips

6" pipe will flow more air, but that 5" restriction will still be the
main limit to your flow. You may end up with probelms of dust settling
in the slower moving air in the 6" pipe rather than carrying thru the
5" into the collector.
If it were me, I would go with 5 " pipe.
Brad