KROHNE BM 702 A EN - Manual (Page 43)

OPERATION
6
43
BM 702 A
www.krohne.com 09/2009 - 4000643301 - MA BM 702 A R01 en
6.5.5 Tank bottom tracing mode (FTB)
The device includes an additional function for measuring reliably low levels in tanks with flat
bottom and poorly reflecting products (low dielectric constant). This tank bottom tracing system
(abbreviated FTB) is activated optionally in the vicinity of the tank bottom (max. 20% level) or for
the whole tank area.
If the measurement jumps to the correct level only after filling above a certain level (approx.
0.3…1.0 m / 1…3.3 ft), you can activate the FTB function Fct. 3.5.7
Fct. 3.5.7 Fct. 3.5.7 Fct. 3.5.7 "Partial". The relative
permittivity ε
r
of the tank product must also be set in Fct. 3.5.8 Fct. 3.5.8 Fct. 3.5.8 Fct. 3.5.8. If it is not known, enter the figure
of 2.0. Since the exact position of the tank bottom must be know for this process, it is advisable
when using the FTB to determine the tank height automatically with an empty tank, using
Fct. 3.5.1
Fct. 3.5.1 Fct. 3.5.1 Fct. 3.5.1.
Activating FTB function Fct. 3.5.7 Fct. 3.5.7 Fct. 3.5.7 Fct. 3.5.7 "Full" expands the tank bottom tracing over the total
measuring range (tank height). This option is intended for tank products with very low
permittivity when also at higher filling level no measurement is possible. With increasing tank
heights, however, measuring accuracy is additionally affected.
6.5.6 Conversion table / volume table
A table consisting of a maximum of 50 points can be stored for non-linear or linear conversion of
the level, e.g. into a volumetric value. This table, however, can only be programmed with the PC-
CAT 2 program (Fct. 3.7.2
Fct. 3.7.2 Fct. 3.7.2 Fct. 3.7.2).
.book Page 43 Thursday, September 3, 2009 2:53 PM