1. The problem statement, all variables and given/known data As shown in the figure, if the pipe net work is shifted bodily by 10m vertically up the tank, and all the other conditions remain the same as the previous figure. Will the volume flow rate change? Or I rephrase it as, in the calculation of elevation head of pipe flow, is the elevation head related to free surface height of the water in tank, or the entrance/exit position of the pipes from the tank? 2. Relevant equations Relevant Equations are: Hf=f L/d V^2/g Hl= K V^2/g 3. The attempt at a solution The attempt at this problem is: I think it is related to free surface height of the water in tank only since in calculation we usually draw a line from one water tank free surface to another.