possibility of removing the measuring unit during the "start-up";
possibility of making the maintenance of the measuring unit, without removing the entire PD meter form the line;
possibility of manufacturing the measuring unit in materials different from those used for the outer housing;
accuracy not influenced by the operating pressure;
availability of different flanges dimensions for the same measuring unit, i.e. for the same max. nominal flow rate;
same measuring unit for all the operating pressures.