A suction bell is like a reducer and is designed to help guide the fluid into the suction pipe. The results in lower friction losses.
I not sure what you mean by suction and discharge CASE. Normally we refer to the suction pipes or manifold and the discharge pipes. Possibly you mean the pump...
Long coupled pumps were really designed to have a spacer coupling so that the pump rotating element (impeller, shaft, seal, backover) could be removed without disturbing the motor thereby keeping your alignment when the pump was reassembled. In reality people do not want to spend the extra money...
I think there is an important issue here which is not always considered properly.
One experience I have had is with bearing seat on shafts. If you machine a shaft to the correct tolerance for a bearing seat by normal machining (ie without finish grinding), then the bearing will correctly to...
