11 Appendix
Levelflex M FMP 40 with Foundation Fieldbus
100
EHauser
Evaluation of the measurement:
•
The map must correspond to the course of the envelope curve (for rod probes up to
approx. 5 cm and for rope probes up to approx. 25 cm before the end of the probe)
when the tank is empty.
•
Amplitudes in the differential curve should be at a level of 0 mV when the tank is empty
and lie within the span that is specified by the probe-specific blocking distances. In
order to not detect any interference echoes, there must be no signals that exceed the
echo threshold when the tank is empty.
•
For partially-filled tanks, the map may only differ from the envelope curve at the posi-
tion of the level echo. The level signal is then detected unequivocally as a positive sig-
nal in the differential curve. For detecting the level echo, the amplitude must lie above
the echo threshold.
Launch pulse
Negative
probe end signal
Envelope curve
Differential curve = Envelope curve Mapping
Mapping
