KROHNE TIDALFLUX 2300 F EN - Manual (Page 33)

TECHNICAL DATA
6
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TIDALFLUX 2300 F
www.krohne.com 06/2013 - 4002490202 MA TIDALFLUX 2300 F R02 en
6.1 Measuring principle
The TIDALFLUX 2000 is an electromagnetic flow sensor with an integrated capacitive level
measurement system, designed for electrically conductive process liquids. The flow rate Q(t)
through the tube is: Q(t) = v(t) x A(t)
Q(t) = v(t) x A(t) Q(t) = v(t) x A(t) Q(t) = v(t) x A(t), in which
v(t) = flow velocity of liquid product
A(t) = wetted area of tube section.
The flow velocity is determined on basis of the known electromagnetic measurement principle.
The two measuring electrodes are located in the lower part of the measuring tube, on a level of
approx. 10% of the inner diameter of the pipe in order to get a reliable measurement up from a
level of 10%.
An electrically conductive fluid flows inside an electrically insulating pipe through a magnetic
field. This magnetic field is generated by a current, flowing through a pair of field coils. Inside of
the fluid, a voltage U is generated:
U = v * k * B * D
U = v * k * B * D U = v * k * B * D U = v * k * B * D
in which:
v = mean flow velocity
k = factor correcting for geometry
B = magnetic field strength
D = distance between electrodes
The signal voltage U is picked off by electrodes and is proportional to the mean flow velocity v
and thus the flow rate q. The signal voltage is quite small (typically 1 mV at v = 3 m/s / 10 ft/s and
field coil power of 1 W). Finally, a signal converter is used to amplify the signal voltage, filter it
(separate from noise) and convert it into signals for totalising, recording and output processing.
The wetted area A is computed from the known inside diameter of the pipe by the patented
capacitive level measurement system that is built into the measuring tube liner. The required
electronics unit is accomodated in a compact housing that is mounted on top of the measuring
sensor. This electronics is connected to the remote IFC 300 F converter by means of a digital
communication line.
Figure 6-1: Measuring principle TIDALFLUX
1 Electrodes
2 Induced voltage (proportional to flow velocity)
3 Capacitive plates in liner for height measurement
4 Magnetic field
5 Field coils