Flow Differential Pressure


Differential pressure measurement is a universal flow measurement for liquids, gases and vapors, composed of flow meters that work on the principle of partially obstructing the flow in a pipe. They introduce a constriction in the pipe that creates a pressure drop across the flow meter. When the flow increases, more pressure drop is created, and as a result, impulse piping routes the upstream and downstream pressures of the flow meter to the transmitter that measures the differential pressure to determine the fluid flow. Differential pressure flow meters always provides accurate results even with large bores, high temperature and extreme pressure.


Endress + Hauser offers two lines of differential pressure products for flow measurement. The Deltatop line is an internationally standardized system with primary flow elements such as average pitot tubes, orifice plates, chambers, nozzles and flange taps that all work together seamlessly for the most accurate differential pressure measurement. The Deltabar is a differential pressure transmitter with metal sensor for measurement of pressure differences, offering long term stability for up to 5 or 10 years and suitable fo SIL2 or SIL3 applications. Website


Verabar provides the most accurate, reliable technology for measuring gas, liquid and steam as well as the lowest operating and installation costs. Developed from aerospace technology, the Verabar averaging pitot flow sensor provides unsurpassed accuracy and reliability. With its solid one-piece construction and bullet shape, the Verabar makes flow measurement clog-free and precise. The unique sensor shape reduces drag and flow induced vibration, and the location of the low pressure ports eliminates the potential for clogging and improves signal stability.

Improved accuracy is derived from the development of a verified theoretical model that predicts the Verabar flow coefficients. Verabar is designed to locate low pressure ports on the sides of the sensor, forward of the fluid separation point and turbulent wake area to eliminate clogging and ensure an extremely stable signal.



Accelabar is a new and unique flow meter that combines two differential pressure technologies to produce high accuracy and low velocity flow rates at turndowns tested up to 65:1 with no straight run requirements. The Accelabar consists of a unique toroidal nozzle design and a Verabar averaging pitot. The nozzle has a patented "settling distance" that accelerates, linearizes and stabilizes the velocity profile sensed by the Verabar. The Verabar located within the nozzle accurately measures and significantly increases the differential pressure output to increase the operating range (turndown).

Accelabar comes ready to install with single or dual transmitters, maintains a constant flow coefficient over a wide range of flow rates and differential pressures, and eliminates the need for calibration

idSolutions offers several primary flow elements including - Wedge meters, Venturi tubes, a Cone Meter, Nozzles, Orifice Plate Assemblies, and Multi Port Self Averaging Pitot Tubes. These instruments are engineered to meet the most demanding flow metering applications and required standards including ASME MFC-3M, ISO 5167, AGA 3, PTC-6, PTC-19.5, B31.1 and B31.3. These well-established technologies use differential pressure measurement across various flow restriction designs to measure velocity, volumetric and mass flow as described by simple laws of physics. Website