KROHNE BM 102 Handbook - Manual (Page 49)

BM 102 49
3.4.1 Gauge operating logic when the reflection is lost
The product reflection pulse is usually lost when the level is in the top dead zone or near the
bottom of the tank. The diagram below shows the action taken by the gauge depending on where
the last reflection was lost. Use PCSTAR2 F8-Marker display function or HART
® HHC Fct. 4.0
Watch Status to follow the measurement status of the gauge.
Zone 1 : Dead and detection delay zones
Marker “Tank full” and “Level lost” is displayed
when the product enters the dead zone and no
reflection is found. This will also occur once the
level reflection is within the detection delay
zone.
The gauge assumes the tank is full and
displays the maximum level value.
The gauge searches for a reflection along the
entire length of the probe.
Zone 2 : Full zone (& dead zone)
Marker “Tank full” is displayed in this zone.
If the gauge loses the signal in this zone, it
reacts as in zone 1: the tank is assumed to be
full.
The gauge searches for a reflection along the
length of the probe.
Zone 3 : Central measurement zone
The gauge searches along the length of the
probe for the largest pulse reflection.
If the pulse is lost the reading freezes at the
last value.
Marker “Level lost” will be displayed. The
probe will search for a reflection along the
length of the probe.
Zone 4 : Empty zone
* if L > 2 m or 6 ¾ ft
If the reflection is lost here then the gauge
assumes the tank is empty and marker “tank
empty” is displayed. The gauge searches for a
reflection in this zone but makes a search
along the entire length of the probe once every
minute.
The reading will remain frozen during this time.