Evoqua WALLACE & TIERNAN MFC, Instruction Manual

Page: 164 / 268

164
WT.050.580.000.DE.IM.0714
Operation
MFC
5.
Calib Mod1
Calib Mod2
Calib Mod3
Calib Mod4 In 3 electrode cells and membrane
sensors
Slope error - the sensor current
based on 1 mg/l has fallen below
the required minimum
In measuring range:
70 µA: min. 0.2 µA/mg/l
100 µA: min. 0.4 µA/mg/l
200 µA: min. 2 µA/mg/l
1000 µA: min. 4 µA/mg/l
Check whether there are air bubbles on
the membrane sensor and remove, if
necessary
Service membrane sensors - replace
electrolyte/membrane cap
Clean 3 electrode cells, replace cell
sand
In pH
In pH 7 calibration, the
sensor signal is outside
-100 to +100 mV or the sensor
sends a signal outside 46–70 mV
pre pH increment
The calibration point distance is
smaller than 1 pH increment Check electrodes,
Check buffer solutions,
Replace, if necessary
In mV
The mV electrode correction offset
is outside -50 to +50 mV Check electrodes,
Check calibration solution,
Replace, if necessary
Conductivity
Conductivity measurement spread
is smaller than 0.8 or larger than 1.2 Clean sensor,
Inspect,
Replace sensor, if necessary
Fluoride
The rate of change of the sensor
curve is too small or the calibration
limits have been exceeded
0.2 mg/l: 40 to 160 mV
2.0 mg/l: -10 to 100 mV
20 mg/l: -60 to 40mV
The lower cal. value sensor voltage
must be 20 mV higher than the
upper cal. value
Check electrode, cable and standard
solution, use fresh standard solution,
replace electrodes
Cl
2
++ pH value smaller than pH 6.00 or
larger than 8.75 Check pH measurement or pH
correction, calibrate pH sensor, if
necessary
Error message Cause Remedy