There are advantages and disadvantages to each design: CLOSED IMPELLERĬan compensate for shaft thermal growth, but if there is too much axial growth the vanes may not line up exactly with the discharge nozzle. For the losed impeller you will need wear rings.For the open inmpeller design you have to set the inpeller to casing clearances.Did you get the difference? High pressure always flows to low pressure, so we now have two separate methods of restricting internal recirculation that can lower the efficiency of your pump and generate a lot of unwanted heat to the product you’re moving.
