If a person took a water pump and attached to a hose and ended up with (random numbers) 15 gpm and 30 psi at the end of the hose, what would happen if you put an exact same pump right next to it and hooked the two pumps together with a quot;Yfitting to a single hose? Would both the gpm and psi be doubled, or neither, or just one? What would happen?
Any discharge piping system down stream of a pump (in this case a hose) will have a pressure drop that varies with flow. You can develop a curve of this pressure where flow rate is plotted against pressure drop. Any centrifugal pump will have a performance curve. The lower the discharge head (pressure) the more the pump will pump. The higher the head the less the pump will pump. Assuming these are centrifugal pumps then their performance will balance with the system pressure drop curve to seek a point on each pump's operating curve that matches the overall system pressure drop curve. In other words the pressure will go up some and the flow rate will also go up some but neither will double.
Only the GPM would be doubled if the pumps are connected in parallel as described. The Pressure would remain at 30 psi. If you were to connect them in series you could double the pressure to 60 psi, but the GPM would remain the same.
GPM would double assuming you don't try to push more water through the hose than it can handle. Pressure you can control by squeezing down on the hose. They are related V1 * P1 = V2 * P2 V = volume P = Pressure
