User's Manual

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TI : TNK-42SmartRadar Refl. Diagram.
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15-01-1999 12:57
BA417-1899001-D1
: TSS_032.RD3
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Commissioning
Page 28
Figure 3.9 Example of reflection diagram with obstructions marked for AdvancedDSP
It is advised to use obstruction area’s for recognizable obstruction peaks that stay below the zone threshold
(for instance: welding seams from the tank shell or stilling well, or roof truss). Obstructions from welding
seams can be recognized as they appear at regular intervals. Refer to figure 3.9.
Select the peaks in the reflection diagram, which are known to be caused by an obstruction.
Mark the obstructions with an obstruction zone. The length of the obstruction zone should be at least 0.8 m.
As the bottom reflection and the antenna reflection belong to the obstructions, it is advised to define
obstruction zones in front of the antenna position and the bottom position.
For the AdvancedDSP level calculation, the obstruction threshold should be set below the product threshold
(e.g. at 5 dB).
The reflection diagram in figure 3.9 shows three obstructions at equal distances. It can therefore be
assumed that there is a fourth obstruction (at approximately 11 metres ullage), though not visible in this
diagram because it is submerged. For a clear overview of all obstructions, it is recommended to make a
reflection diagram when the tank is empty.