If we have an open pipe system that will deliver in total 200 gpm divided in 2 pipes the first pipe is 50 gpm and the second is 150 gpm , the 2 pipes have the same length , if we want to size the pipes where both pipes will have the same diameter , if we do that through william hazen eqution flow chart we will get for each pipe a different head loss "slope" m/100m head loss. my question is first , how does water chose between the 2 pipes that have the same diameter and length to go in the fist 150 gpm and the second 50 gpm ???? my 2nd question is : according to bernoulli energy balance the head loss between "o &a" and "o&b" should be equal the same because Po/guamma +Va square /2g -hl =0+vasquare/2.g and po/guamma +vbsqaure/2g - hl =0 +vbsquare/2g p.s: check the picture below for more explanation. so the head loss must be the same , but using hazen william equation show us that they are not the same.??? p.s:the system is open to the atmosphere. p.s:a pump is used to deliver the 200 gpm.