I am designing centrifugal pump. The only data I have is pressure difference means inlet & outlet pressures and temperatures. I didn’t know pipe diameter, velocity, area etc…I performed discharge calculations and for that I choose schedule 40 pipe with 3.5 inch nominal pipe size. Now for suction section the pipe size I choose is greater then that of discharge section (greater in term of diameter).
The diameter of the suction pipe is always greater than discharge in pumps and compressors. It is because the kinetic energy provided by the machine is converted to pressure energy due to the low diameter of the pipeline.