A channel impeller works directly on the pumped liquid with the liquid passing through the impeller itself. A channel impeller can be described as a closed, semi-open or open impeller.
The impeller can have one or more channels of varying size allowing for free passage of impurities up to a particular size. In impellers with more than one channel, fibrous impurities might get caught on the leading edges of the vane, causing the pump to clog.
Channel impellers can have efficiencies as high as 80-85 %. Liquid with a high sand content will cause problems with impeller clearance on a channel impeller.
Grundfos submersible and dry-installed wastewater pumps in particular are available with channel impellers combining high efficiency and large free passage.