Emerson Rosemount 5408 Reference Manual page 268

Configuration parameters
February 2020
Table C-6: Empty Tank Handling
Parameter
Empty tank detection area
Bottom echo visible when tank is empty
Related information
Enable bottom echo visible when tank is empty
Tank bottom projection
The Tank Bottom Projection is used to enhance measurement performance near the
bottom of the tank. When the tank bottom echo is strong (typical for flat tank bottoms)
and the dielectric constant of the product is low (e.g. oil), the transmitter may lock on the
bottom echo and report a false level measurement (empty tank). This problem can be
solved by using the Tank Bottom Projection function.
Table C-7: Tank Bottom Projection
Parameter
Bottom product dielectric constant
Maximum projection distance
Minimum tank bottom amplitude
Related information
Use tank bottom projection
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Description
The Empty Tank Detection Area defines a range
where it is accepted to lose the echo from the
product. If the echo is lost in this range, the tank
is considered empty and the level is presented
as 0.
When the tank is empty, the transmitter looks in
this range for the product surface. When a new
echo is found in this range, it is considered to be
the product surface. Therefore, if there are
disturbance echoes in this area, they may need
to be filtered out.
This function requires the Bottom echo visible
when tank is empty parameter to be disabled.
Only enable this parameter if the bottom echo is
visible when tank is empty. By setting this
parameter, the bottom echo will be treated as a
disturbance echo to facilitate tracking of weak
surface echoes close to the tank bottom.
Description
Enter the product dielectric constant for the
product in the bottom of the tank.
This defines the range where the function is
active. Enter the maximum distance from the
zero level (tank bottom).
Enter the minimum allowed amplitude for the
echo from the tank bottom before this function
is activated.
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Reference Manual