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Description
Page 5
3. Description
The 801 electromagnetic flow meter uses the Faraday principle to measure the flow of water past
the sensor. Two different types of sensor are available for the 801: the cylindrical sensor and flat
sensor.
The cylindrical sensor has its electrodes on the side and the volume of water that is being sensed is
a spherical volume around the sensor to a diameter of about 120mm. Because of this relatively
large sensing volume, the cylindrical sensor should not be used in situations where the water
boundary [bottom, sides or surface] is closer than 40mm to the sensor.
The flat sensor has the sensing electrodes on one surface of the sensor and these should normally
be facing uppermost. The volume of water whose flow is being sensed is a cylinder between the
electrodes and extending to approximately 10mm above the sensor. This sensor is therefore also
suited to shallow applications. Because of the small sensing volume, if the water is turbulent, the
real time readings of the flat sensor will fluctuate more than those of the cylindrical sensor.
The sensor should be aligned into the flow and the calibration is determined for +ve flow [flow on
to the sensor at the electrode end] with the sensor upstream of the wading rod.
The sensor will detect negative flow and the same calibration is used, although there will normally
be some interference caused by the turbulence from the wading rods. The unit is set to measure
speeds up to 5 M/sec in both directions.
© 2016 Valeport Ltd
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