Application Challenges; Handling Disturbances At Top Of Tank - Emerson Rosemount 5408 Reference Manual

Service and Troubleshooting
Use AMS Device Manager and Field Communicator
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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:
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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
general guidelines.
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
Procedure
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Select Configure > Manual Setup > Device Setup > Security.
Under Security, select Change Write Protection and follow the on-screen
instructions.
Set amplitude threshold section
Extend the Upper Null Zone
In Rosemount Radar Master Plus, start the echo curve reading, see
View the echo curve plot to find out if there are disturbing echoes close to the
transmitter.
Calculate the required distance to the first endpoint.
Distance = Nozzle height + 2 in. (50 mm) =
In the echo curve, click the first endpoint and type the calculated value
Select Save.
Amplitude thresholds
(Figure 7-9).
Section 7.4.1.
(Figure
Reference Manual
for
7-9).