About Differential Pressure (DP) Flow Measurement

About Differential Pressure (DP) Flow Measurement

Rosemount and Daniel DP Flow solutions enhance measurement capabilities using innovative design with proven technology.


Improve Productivity with DP Flow Measurement

As one of the most common technologies for measuring flow in a pipe, differential pressure flow (DP Flow) measurement has a long history of achieving high accuracy and repeatability. The DP flow rate of process fluids is derived from the pressure differential caused by an engineered restriction within the pipe. This unique and scalable measurement technology enables integrated pressure, flow and temperature solutions and provides reliability and increased plant productivity.

About DP Flow Technology

Three essential elements are required to engineer a differential pressure flow meter. The primary element creates a pressure drop across the flow meter by introducing a restriction in the pipe, and this engineered restriction enables Bernoulli’s equation to be used for a flow rate calculation. The pressure drop is measured by a secondary element, a differential pressure transmitter, while tertiary elements consist of everything else within the system, such as impulse piping and connectors.


Orifice fittings are widely used in the oil and gas industry to measure gas, liquid and even fluids with a small amount of second phase. Common components of an orifice measurement system include the fitting, the plate and the plate carrier. The plate along with the adjacent part of the pipe and the pressure connections constitute the primary element. Cost-effective and straightforward, this technology offers high accuracy without calibration and is easy-to-use and troubleshoot.


There are many kinds of primary elements that provide options for most line sizes and flow rates. These options include standard and conditioning orifice plates, averaging pitot tubes, Venturi tubes, flow nozzles, cones and wedges. With many mounting configurations, these primary elements also feature tighter process control due to low signal noise, high accuracy, low maintenance cost and integral temperature sensor options for reduced process penetrations.


DP Flow is proportional to the square root of differential pressure, making pressure a critical component of DP Flow calculations. Other factors that influence the mass flow include: density, viscosity, temperature, pipe diameter and fluid type. In many industrial processes, numerous measurement and control devices are used to ensure accurate liquid, gas and steam flow rates for increased safety, productivity and cost-efficiency.


For best-in-class performance, MultiVariable™ transmitters measure static pressure, differential pressure and temperature and can be engineered to calculate flow. Flow meters can provide process variable outputs as well as calculated real-time mass, volumetric or energy flow. Calculated flow output delivers accurate, reliable information quickly for improved process performance.


DP Flow measurement can be utilized to optimize many aspects of a process, including product consistency, custody transfer, production efficiency and safety applications. Daniel and Rosemount DP flow measurement solutions are versatile, easy to install and troubleshoot.  Devices are suitable for use in a wide range of fluids including corrosive liquids, slurries, saturated or superheated steam, gas and many other process applications.

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