At this point also in centrifugal due to high rpm since it is directly coupled to electric motor the pump creates partial vacuum this means the liquid will certainly flow through vacuum therefore the liquid will be recieved at the centrifugal pumps suction and since the impeller rotates the fluid will be displaced aside Centrifugal Vacuum Pump forward with a specific energy.

A vacuum pump gets the inlet hooked up to one or both valve covers, sometimes the valley pan. It SUCKS the atmosphere from the engine, hence reducing the atmosphere pressure build up created by blow due to combustion gases going past the piston rings in to the pan.