Although the very large axial flow and mixed flow impellers we were discussing throughout the post have the ability to pass large solids due to their large passageways, they are not considered true Non-Clog impellers.
Non-clog impellers are very special 2 vaned impellers with rounded leading edges and oversized passageways that help to pass long stringy solids. Long stringy solids tend to accumulate at the impeller entrance and cause problems for the typical 4-5 vaned prop. or mixed-flow impeller with sharp leading edges; especially imbalance.
While in terms of specific speed, a Non-Clog impeller may have the "characteristic curve" of a mixed-flow impeller; the reverse cannot be said. Your mixed-flow turbine "water mover" does not have a Non-Clog impeller; nor does a prop pump.
Non-clog impellers are also extremely inefficient whereas prop and mixed flow impellers typically have the highest efficiencies of all centrifugal class pumps.
The distinction I was trying to make in your influent was whether your application was mostly drainage/stormwater overflow with intermittent waste solids, in which case a prop or mixed flow pump could be very acceptable, or whether the inflow was truly dedicated to raw sewage; whereas you should move to true Non-Clog impellers.
You say the impellers will definitely be Non-Clog and that is your call; so be it. Just remember there certainly is a distinction between the types; and before you get to the finer points of detailed flow and heads, you should be very clear in your mind that you need true Non-Clogs. Power consumption will be greatly affected. I think municipalities are still concerned with money??
