Emerson Rosemount 5400 Series - Registration of False Echoes

135
Reference Manual
00809-0100-4026, Rev HA
Section 7: Service and Troubleshooting
November 2014
Service and Troubleshooting
7.3.3 Registration of false echoes
The False Echo function improves the performance of the gauge when the surface is close to a
horizontal surface of a static object in the tank. The object causes an echo when it is above the
surface. When the echoes from the surface and the object are close to each other, they may
interfere and cause a decrease in performance.
Figure 7-5. The Rosemount 5400 Series can Handle Disturbing Radar Echoes
The False Echo function allows registration of disturbing echoes caused by objects in the tank.
When the surface is passing a disturbing object, the transmitter measures with higher reliability
if the position of the object is registered. This makes it possible to detect a product surface close
to a disturbance echo even if the surface echo is weaker than the disturbing echo. Follow these
recommendations before registering new interfering echoes:
 Make sure a correct ATC is set before registering any disturbance echoes (see “ATC” on
page 84).
 Compare the list of interfering echoes with the tank drawing or visual inspection of the
tank. Note any objects like beams, heating coils, agitators, etc. which correspond to the
found echoes. Only register echoes above the ATC which can be clearly identified as
objects in the tank, keeping the number of registered echoes to a minimum.
 Make sure the level is stable before registering a disturbance echo. A fluctuating level
may indicate a temporary disturbance that is not from an interfering object.
 Do not register False Echoes located below the product surface. It is recommended that
registration be done when the tank is empty.
False echo
Surface echo
Disturbing
objects