ABB FS4000, Operating Instruction

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Design and function
20 FV4000 / FS4000 D184B097U02
2.1.2 Swirl flowmeter
The inlet pipe converts the axial flow of the incoming media into rotational movement. In the
center of this rotation a vortex core is formed which is forced into a secondary spiral-shaped
rotation by the backflow.
The frequency of this secondary rotation is proportional to the flow and, if the internal geometry
of the meter exhibits an optimum design, will be linear over a wide flow range. This frequency is
measured by a piezo sensor. The frequency signal from the flowmeter sensor, which is
proportional to the flow, undergoes downstream processing in the transmitter.
G00702
p1 V
T2
V
T1
V = 0
A
V = 0
A
p2
1 2 3 4
5 6
Fig. 8: Principle of measurement of the Swirl flowmeter
G00601
1 3
5 4
2
Fig. 9: Principle of measurement of FS4000-ST4/SR4 Swirl flowmeters
1 Inlet pipe
2 Piezo sensor
3 Outlet pipe
4 Stagnation point
5 Housing