What would the effect on the mass flow rate be if a measurement orifice plate was added to the pipeline? Would the mass flow rate be the same with or without the orifice plate in the pipeline? I have read that due to the conservation of mass, adding a measurement orifice to the pipeline will have no effect on the mass flow rate. This is due to the velocity speeding up through the orifice and the recovery pressure on the downstream side. Is this true?
Your supplier tasked with sizing the plate will provide the pressure loss introduced.
Properly sized, depending on the application, the pressure loss is minor.
Orifice will introduce additional pressure drop in the fluid flow. As a thumb rule you can assume pressure loss due to orifice will be approx. 0.2 bar. Now if your overall system pressure drop is much higher than this, then you won't notice any significant drop in flowrate. But if your overall system pressure drop is comparable to orifice, then you will notice a significant drop in flow rate and hence mass flow.