The open impeller has only blades and blade stiffeners, and no front and rear cover plates. The number of open impeller blades is less than 2-5. The pump impeller has low efficiency and less application. It is mainly used to transport liquid with high viscosity and slurry liquid.

The runner impeller is a curved flow channel from the inlet to the outlet. This type of impeller is suitable for conveying liquid containing large particle impurities or long fibers. Because this type of impeller has excellent anti-clogging performance. But its disadvantage is that its cavitation resistance is weaker than other forms.