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?