Primary element flow meter for gas, steam and liquid

In fluid mechanics, a flow primary element is a device used to restrict the flow of a fluid while measuring the pressure difference. The main application is is flow measurement using a pressure transmitter differential pressure transducer. This measures the pressure on both sides of the orifice to calculate the flow rate. Orifice plates, nozzles, venturis, and V-cones are flow primary element. The conditions for their installation are described in ISO 5167 norms.

Differential pressure flow measurement is one of the most widely used measurement principles in the industry.

The main field of application is the measurement of water in heating and cooling circuits and the measurement of steam and condensates at very high temperatures in secondary circuits.

flow measurement using differential pressure and primary element


Measurement principle

The aim is to create a localized restriction of the section (or constriction), within the pipeline, which will generate a differential static pressure. Its measurement will allow the flow deduction.

fuji electric guides you in choosing the most suitable technology

Fuji Electric France helps you to choose the most suitable technology for your application

Depressant organs
Orifice plate and
corner taps

Integrated orifice placeVenturis and NozzlesAverage Pitot tubesV-ConeTM flow meter
orifice plates diaphragmsflow meters with integral orificeNozzlesmedium pitot tubesv cone flow meters
Diameter mini.DN501/2 NPTDN50DN50DN15
Diameter max.DN10001/2 NPTDN800DN1500DN3000
Static pressure max.500 bar160 barAll50 bar689 bar
Temperature max.200°C120°CAll350°C450°C
Reynolds numbers>2 500>2 500>20 000>12 000>4 000
Straight lengths
Accuracy± 1,5 %± 2 %± 1%± 1%± 0,5%
Load lossAverageAverageAverageLowLow
Applications             Gas, steam, corrosive and non-corrosive fluids

Primary element : essential for accurate, reliable fluid measurement!