Pump Flow and NPSH Calculations

Bernouellies equation confirms that pressure will be the same in all the connections of your branch, the pressure and hence the floew will vary at the end of each line due to friction losses and the length of pipe in that branch circuit. It is not simple to answer the the flows through each of the sizes mentioned, simply because the velocity will change through each size, ( if the input pressure remains constant.)

I'm not sure what your "closed loop" entails,but here is some formula to use (freely on web)

Suction lift

NPSH = Ha -Hvpa - Hst - Hfs

For flooded suction:

NPSH = Ha -Hvpa +Hst -Hfs

To determine the type of flow you need to calculate the Reynolds number. Without values noone will be able to help you further.

for 1- you need to know the pressure drop on the line as well as the size of the pipe. Also, the inlet pressure must be maintained.

2- In a closed circuit, you also need friction losses at the flow rate required. The physical height (metres) become irrelevant since the pump is circulating the fluid.... presure losses will dictate the characteristics...

3- There is no theoretical maximums. It all depends on how much pressure you can develop at the inlets to overcome the losses due to each type of flow. This becomes the domain of Hydrodynamics etc... Take a course and save yourself... or give the necessary actual values if anyone would like to give you the answers...