Differential pressure flow meters are among the most common and traditional types of flow measurement instruments used across various industries, particularly in the oil and gas sector. These meters create a restriction or obstruction in the flow path—such as an orifice plate, venturi tube, or nozzle—which increases the fluid velocity and generates a pressure difference between two points upstream and downstream of the restriction.

This pressure difference is measured by differential pressure (DP) transmitters and, using standard equations, is converted into volumetric or mass flow rate of the fluid.

The main advantages of differential pressure flow meters include simple construction, high reliability, and cost-effectiveness. The orifice plate, as the most common type of DP meter, is widely used for gas and liquid measurement due to its ease of installation and maintenance and predictable performance.