28
4 Mounting
NCR-84 Two-wire 4 … 20 mA/HART
51141-EN-181127
Fig. 24: Alignment in liquids
If there are agitators in the vessel, a false signal suppression should
be carried out with the agitators in motion. This ensures that the
interfering reflections from the agitators are saved with the blades in
different positions.
Fig. 25: Agitators
Through the action of filling, stirring and other processes in the vessel,
compact foams which considerably damp the emitted signals may
form on the product surface.
If foams lead to measurement errors, you should use the biggest pos-
sible radar antennas or sensors with guided microwave.
4.5 Measurement setup - Flow
In general, the following must be observed while mounting the sensor:
•
Mounting the sensor on the upstream or inlet side
•
Installation in the centre of the flume and vertical to the liquid
surface
•
Distance to the overfall orifice or Venturi flume
•
Minimum distance to the max. height of damming
The following examples are used as an overflow of the flow meas-
urement, detailed planning information is available from the flume
manufacturers and in special literature.
Agitators
Foam generation
925-0373 Rev A