Differential pressure (DP) and flow meters are devices used to measure the flow rate of a fluid in a pipeline or a closed system.

Differential Pressure (DP) Meters work by creating a pressure drop across a constriction in the flow path and measuring the pressure difference upstream and downstream of the constriction. Common types include orifice plates, venturi meters, flow nozzles, and pitot tubes.

Flow meters measure the flow rate directly, without relying on a pressure difference. Various types include Magnetic Flow Meters (using electromagnetic induction), Ultrasonic Flow Meters (using ultrasonic waves), Vortex Flow Meters (based on the von Kármán effect), Coriolis Flow Meters (based on the Coriolis effect), Positive Displacement Flow Meters, and Turbine Flow Meters (based on turbine rotation).

Both types of meters find applications in industries such as oil and gas, water treatment, chemical processing, and HVAC systems, to accurately measure flow rates of liquids and gases. The choice between differential pressure and other flow meters depends on factors such as accuracy requirements, cost, and the properties of the fluid being measured.