Hydraulic power can be calculated by multiplying the pressure and the flow rate,
In order to get the power at the shaft, we must add an efficiency term that is specific to each pump,
The familiar form of this equation in English units is,
Using approximately 85.1% efficiency the equation becomes,
The following calculator will solve for any variable in the equation and will convert between different units
The general equation that relates shaft power to torque and angular velocity is,
In English units this equation can be expressed as,
If the pump is to run at a speed less than the BASE SPEED of the motor we must insure that the torque is sufficient. We can calculate the maximum TORQUE available using the motor's BASE SPEED and nameplate HORSEPOWER
If we set the pump torque equal to the motor torque and combine the two equations we can show that,
To find the RPM of the shaft we must refer to a graph of PUMP FLOW versus RPM supplied by the pump manufacturer
