In principle, you may measure the flow in any point of the circuit.

I see however a possibility of a problem, which may occur with flowmeters based on the pressure loss introduced by an obstacle (orifice plate, discharger type, etc). In case you put one of those before the pump, you may cause cavitation inside the pump if the intake flow pressure is too low.

So, the answer depends on what type of flowmeter you are using...

Raja suggestion of avoiding disturbed zones is very correct. Try to put it on a straight part, preferably more than 5 diameters away from a preceeding curve, to allow a stabilization of the velocity profile.

Dear hakeem,

in my view & as per law of continuity volume flow rate is constant at any point during the flow. But i recommend to keep the flow meters away from the disturbances to reduce uncertainties.

I thought that the flow meter works based on the average flow rate; so it does not that matter to place it before or after the pump.

In principle, you may measure the flow in any point of the circuit.

I see however a possibility of a problem, which may occur with flowmeters based on the pressure loss introduced by an obstacle (orifice plate, discharger type, etc). In case you put one of those before the pump, you may cause cavitation inside the pump if the intake flow pressure is too low.

So, the answer depends on what type of flowmeter you are using...

Raja suggestion of avoiding disturbed zones is very correct. Try to put it on a straight part, preferably more than 5 diameters away from a preceeding curve, to allow a stabilization of the velocity profile.

About your question about the fluctuation due to turbulence:

The time scale of a oval gear flowmeter is farway from the time scale of the pump induced turbulence. The rotation speed of the flow meter will integrate the flow rate information on a time interval much larger than the scale of the fluctuations associated to the rotor blades of the pump and the vortices generated by them. I think that the best location is to put it after the pump, far enough to allow a stabilized shape of the mean velocity profile

You can. Please read the installation guidelines for the flow meter you are planning to install

I agree with Napoleon

Thanks a lot to all for the valuable inputs

Yes you can, but better not. You must avoid cavitation problem.

Yes, the formation of cavity leading to disturbance in flow rate is a major problem which we observed. In order to avoid this problem we put an empty GW bottle after pump and then a rotameter as flow meter. This arrangement gave a constant flow rate without any disturbance.