# When finding flow generated by a pump, where do points A and B go?

I tried to find the answer in past posts, but couldn't locate it.

I have a pump (100% efficient, for simplicity) that runs on 100kW and follows the equation: Power(pump) = (Specific Weight)(Flow)(Pump Head). The flow is steady, but not inviscid. We are given info for losses.

My specific question is this: Where should points A and B be located for a Bernoulli equation designed to account for the energy imparted to the fluid by the pump? I must calculate flow imparted by pump.

Should I place point "A" at the pipe entrance? Or, perhaps, right before it? I'm confused.

An illustration is attached and, as this question is quite specific, please let me know if any information is needed. I have a solution, but want to grasp the concepts enough to understand what is happening, physically.

Let me know if more info is needed, or if I've overlooked a post from the past. Thanks, everyone.

• There are two different questions here, which require two different answers: one about where to put the (pressure measurement) points so that the Bernoulli equation between them can reveal how much energy is added by the pump, the other about where to put the (pressure measurement) points so that the Bernoulli equation between them can reveal the flow rate. @kamran's answer is good for the first question. May 25, 2021 at 7:59

$$P_{p}= W{in}\cdot\gamma /Q \quad and\ \gamma =1$$ in your pump.
$$P_1+1/2 \rho v_1^2+ \rho gh_1 +P_p= P_2+1/2 \rho v_2^2+ \rho gh_2 + f_h\rho g$$