Emerson Rosemount 5408, Reference Manual

Page: 132 / 274

7.5 Application challenges
7.5.1 Handling disturbances at top of tank
There are two general methods for managing disturbance echoes at the top of the tank:
• Set amplitude threshold section
• Extend the Upper Null Zone
Set amplitude threshold section
If necessary, a customized amplitude threshold section can be used to block out
disturbing echoes (e.g. from the tank nozzle or bypass well inlet). Refer to
Amplitude
thresholds for general guidelines.
Prerequisites
Amplitude threshold sections are pre-configured at the factory for transmitters with
process seal antenna. For nozzles taller than 10 in. (25 cm), it may be necessary to
manually increase the distance value for the first endpoint (
Figure 7-9 ).
Procedure
1. In Rosemount Radar Master Plus, start the echo curve reading, see Using the echo
curve .
2. View the echo curve plot to find out if there are disturbing echoes close to the
transmitter.
3. Calculate the required distance to the first endpoint.
Distance = Nozzle 2 in. (50 mm) =
4. In the echo curve, click the first endpoint and type the calculated value ( Figure 7-9 ).
5. Select Save .
Figure 7-9: First Endpoint
A. First endpoint
Service and troubleshooting Reference Manual
February 2020 00809-0100-4408
132 Reference Manual