Target meters:

•A sharp-edged disk is set at right angles to the direction of flow.

•The drag force exerted on the disk is measured and is related to the flow rate of the fluid.

•The drag force in this case is analogous to the frictional force exerted by the fluid on wall of a conduit.

Calibration of Target meters:
 

•Target meters can be calibrated using the same principal as that of frictional force exerted on a wall of a conduit.
 

•Flow rate = Fluid density* Sqrt of drag force

•The drag force in this case is equivalent to the frictional force exerted by the fluid on the wall while flowing through a conduit
 

Advantages of Target meters:

• They are kind of expensive and rugged.

•Can be used with a wide variety of fluids, even viscous fluids and slurries.