How to Calculate Pump Shaft Torque from Flow Rate, RPM, and Diameter?

[Zarathuztra]

Attempting to determine the torque on the shaft of a pump. Known values are flow rate, RPM, and shaft diameter.

1. What other values are needed to make the calculation?

2. What is the equation I can use for this?

 

[CWatters]

1) Pressure and Efficiency I think.

2)
Output power = pressure * flow rate
Input power = output power/efficiency
Input power = Torque * Angular velocity

Make sure you are consistent with the units.

 

[russ_watters]

Is the pump itself known or are you trying to pick one? You don't necessarily need to calculate or pick the rpm.