Offset level, V3H1 The offset is the hydrostatic pressure in mbar acting on the probe when the vessel is
filled to the desired »empty« level. When the value is entered at V3H1, the Silometer will
indicate 0 for this level.
• If the default value 0 is used, the zero level is at the point of installation of the
Deltapilot probe.
The hydrostatic pressure is calculated from the density and »empty« level:
p
mbar
= ρ (kg/dm
3
) x g (m/s
2
) x ∆h (m) x 10 mbar
Example
The Silometer must display 0 for an »empty« level of 45 cm water, the offset p
mbar
is:
p
mbar
= 1.0 x 9.807 x 0.45 x 10 = 44.13 mbar
Display sensitivity, V3H2 The sensitivity specification in V3H2 determines the increase in the measured value
per mbar pressure rise at the Deltapilot S probe.
Sensitivity
mbar/digit
= p
max
/required display at V0H0 for p
max
Example
The maximum level 10 m corresponds to 1526 m
3
p
max
= ρ (kg/dm
3
) x g (m/s
2
) x h (m) x 10 mbar
= 1.0 x 9.807 x 10 x 10
= 980.7 mbar
To display volume (m
3
)
Sensitivity
mbar/digit
= 980.7/1526 = 0.64266 mbar/digit
To d i s p l a y level (m)
Sensitivity
mbar/digit
= 980.7/10 = 98.07 mbar/digit
Procedure The calibration, described here for operating mode 1, should be carried out preferably
with an empty tank (probe at bottom, dry and unpressurized). If tank is partially filled,
take over f0 from stick-on label.
• Initial filling of the tank should be carried out under close supervision so that
the results of a possible calculation error can be recognized in good time.
Step Matrix Entry Significance
1 V9H5 e.g. 672 Reset transmitter
2 - »E« Register entry
3 V0H2 e.g. 1526 Enter volume used for sensitivity calculation
- for level measurement enter level (e.g. 10 m)
4 - »E« Register entry
5 V3H5 e.g. 99.5 Enter frequency »f
o
« at V0H8
6 - »E« Register entry
7 V3H6 e.g. 1.054 Enter sensitivity »
∆
f«
8 - »E« Register entry
9 V3H1 e.g. 44.13 Enter offset level (V0H0 = 0 for 45 cm water)
10 - »E« Register entry
11 V3H2 e.g. .6426 Enter display sensitivity (V0H0 = 1526 for 10 m water)
- for level enter e.g. 98.07
12 - »E« Register entry
Silometer FMC 671 Z/676 Z Chapter 8: Other Applications
42
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