Again-- I'm not entirely sure if this goes to physics or engineering, but the word thing that comes in mind when I hear Bernoulli equation is PHYSICS, so I decided to post it here... 1. The problem statement, all variables and given/known data So I have this hydraulic system http://img689.imageshack.us/img689/3596/clipboard01rvt.jpg [Broken] With the figures H1 = Height of suctioning = 3m H2 = Height of delivery = 25m D1 = diameter of the suctioning pipe = 150mm D2 = diameter of the delivery pipe = 100mm Q = 0.02 [m^3/s] y1 = pressure lost at the suctioning line y2 = pressure lost at the delivery line Energy conversation efficency of the pump = 75% Find the pressure at the pump's entrance (p1). 2. Relevant equations In the solution 3. The attempt at a solution So I build the equation: http://img196.imageshack.us/img196/2145/ber1j.jpg [Broken] http://img21.imageshack.us/img21/9740/ber2h.jpg [Broken] HOWEVER, the result in my manual is different. It's p1 = -0.05064x10^5 [Pa] I don't get how could we have gotten such hugely different results!