KROHNE BM 70 A Installation And Operating Instructions Manual page 60

Group DA Display and signal output
No. Fault / Symptom
DA10 Display and signal output frequently
indicate the maximum level.
DA11 Display and signal output indicate
sizeable step changes in the
direction of the maximum (possibly
also mimimum) level.
DA12 Display and signal output indicate
step changes:
→
during filling upwards
→
downwards
during draining
DA13 Signal output (recorder) shows
sinusoidal variations about the
actually measured value (deviation:
up to ± 2 cm) in the upper part of
the tank (approx 2 m).
DA14 Display and signal output indicate
constant measured values, although
the level changes.
DA15 Display and signal output indicate
measured values at the level of the
agitator blades.
DA16 Display and/or signal output
indicate incorrect conversion
values, but level indication is
correct.
DA17 Display and signal output go
suddenly to "zero" or block distance
limit when tank continuously topped
up.
markers 1-6 & in display
Group M
No. Fault / Symptom
(one or several) ON. Reference(s) to possible faulty
M1
markers 1-5
M2
marker 2 ON for long periods or
permanently.
M3
marker 6 ON.
M4
markers 3 and 4 ON.
Level indicator is "zero".
Installation and operating instructions BM 70 A/P
Cause
Excessive amounts of vapour,
condensate or dust in the tank, or
heavy contamination (deposits
thicker than approx. 3 - 7 mm or
0.1" - 0.3") on the antenna.
Antenna cleaning operations cause
strong reflections.
Storage tank: BM 70 A/P mounted
centrically or on dome (manhole
cover).
Process tank with extremely
turbulent product surface.
Storage tank, smooth surface,
steady filling or draining procedures,
incorrect tank type set.
This has physical reasons and
occurs mostly with slow changes in
level when sources of interference
are located in the upper part of the
tank.
Fixed tank internals unfavourably
positioned, thus permanently
simulating a constant level to the
BM 70 A/P. No empty spectrum
recorded and/or measurements
carried out without empty spectrum.
Digital input is activated,
marker 6 is ON, measurement
is suspended (frozen).
Tank with "difficult" agitator blades.
Conversion table set incorrectly.
Level located in range of block
distance in front of antenna, see
Fct. 3.1.2 in Sect. 8.6.3.
Cause
measurements.
Note: very strong reflection signal
(e.g. measurement in the stilling
well).
Digital input is activated,
measurements suspended (frozen).
Device located in block distance
detection range.
This is a status display and not an
error. This usually occurs on tanks
with dished bottom, when the tank is
empty, after the BM 70 A/P has
been switched on or after a new
empty spectrum has been recorded.
Page: 60
Corrective action
Clean antenna (install cleaning device
if necessary). If unsuccessful, enlarge
BLOCKDIST. under Fct. 3.1.2 (see
Sect. 8.6.3) or deactivate Fct. 3.5.6
BD-DETECT (see Sect.8.6.14).
Activate digital input during cleaning
(marker 6 is ON), measurement
suspended (frozen), see Sect. 4.8.
Change position of the BM 70 A/P. For
recommended distance from tank wall,
see Sect. 6.1.2, and note installation
conditions in Sect. 6.1.3!
Or activate "multiple reflection
identifier" under Fct. 3.5.5, see Sect.
8.6.14.
Switch on tank type AGITATOR under
Fct. 3.5.9, see Sect. 8.6.16.
Set correct tank type (STORAGE
TANK) under Fct. 3.5.9, see Sect.
8.6.16.
Avoid all sources of interference in the
upper part of the tank. A bigger
antenna might help to solve the
problem.
Activate the empty spectrum under Fct.
3.5.2 if measurements carried out
without empty spectrum. If empty
spectrum not recorded, record under
Fct. 3.5.2, see Sect. 8.6.12.
Deactive the digital input, see Sect. 4.8
Record new empty spectrum with "
MAX. VALUES" under Fct. 3.5.2. Or
change position of the BM 70 A/P on
the tank. Note conditions described in
Sect. 6.1.2.
Reset conversion table with the PC-
CAT program.
Avoid this operating condition or, if
empty spectrum (Fct. 3.5.2) is
sufficiently good, reduce block distance
(Fct. 3.1.2) as described in Sect.8.6.3.
Corrective action
See Sect. 8.8 for significance of markers
and elimination of possible faults.
Not important if measured value is
correct.
Deactivate digital input, see Sect. 4.8.
Check conditions for block distance
detection, see Sect. 8.6.14.
Fill tank!
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