Full Tank Handling; Double Bounce - Emerson Rosemount 5402 Reference Manual

Advanced Configuration
October 2018
Level alarm is not set when tank is empty
If the echo from the product is lost in the area close to the tank bottom (Empty Tank Detection Area), the
device enters Empty Tank State and triggers an alarm. Two types of alarms are triggered:
Invalid Level (can be seen in the Diagnostics window)

The Analog Output enters Alarm Mode

C.4.3

Full tank handling

Full tank detection area
This parameter defines a range where the surface echo can be lost. If the echo is lost in this range, the
tank is considered full (the device enters Full Tank State) and the device presents maximum level
indication.
When the tank is full, the device searches double the Full Tank Detection Area for the product surface.
When a new echo is found in this range, it is identified as the product surface.
It is important to filter out any disturbances in this area.
Level above hold off distance possible
This function should be enabled if the level can rise above the Hold Off Distance/UNZ and it is necessary
to display the tank as full in that case. Normally, the device will be able to track the surface and the
product level will never rise to that height. If the function is not enabled and the surface is lost at the top
of the tank, the device searches the whole tank for a surface echo.
Note
Measurements are not performed within the Hold Off Distance/UNZ region.
Level alarm is not set when tank is full
If the surface echo is lost, close to the top of the tank. The level value will normally be displayed as
"invalid." This parameter should be set to suppress the "invalid" display.
Note
Setting this parameter disables the analog output so it does not enter alarm mode for invalid levels close
to the antenna.
See "Full tank handling" on page 267
C.4.4

Double bounce

Some radar waves are reflected at the surface and then reflected against the tank roof and back to the
surface before being detected by the transmitter. Normally, these signals have a low amplitude and are
ignored by the transmitter. For spherical and horizontal cylinder tanks however, the amplitude may be
strong enough for the transmitter to interpret the double bounce as the surface echo. Setting the Double
Bounce Possible parameter can solve this type of measurement situation. This function should only be
used if double bounces cannot be corrected by changing the mechanical installation. See
bounce" on page 268
261
for more information.
for more information.
Reference Manual
00809-0100-4026, Rev KC
"Double
Advanced Configuration