KROHNE IFC 070 Converter EN - Manual (Page 7)

PRODUCT FEATURES
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IFC 070
www.krohne.com 04/2009 - 4000572101 - TD IFC 070 R02 en
1.3 Measuring principle
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 = inner diameter of flow meter
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.
1 Voltage (induced voltage proportional to flow velocity)
2 Electrodes
3 Magnetic field
4 Field coils