Single and Dual Input Analyzers for Low Level Conductivity
AX410, AX411, AX413, AX416, AX418, AX450, AX455 & AX456
8 SIMPLE FAULT FINDING
68
IM/AX4CO Issue 11
8 SIMPLE FAULT FINDING
8.1 Error Messages
If erroneous or unexpected results are obtained the fault may be
indicated by an error message - see Table 8.1. However, some
faults may cause problems with analyzer calibration or give
discrepancies when compared with independent laboratory
measurements.
8.2 No Response to Conductivity Changes
The majority of problems are associated with the conductivity
cell which must be cleaned as an initial check. It is also
important that all program parameters have been set correctly
and have not been altered inadvertently - see section 5, page
19.
If the above checks do not resolve the fault:
1. Check the analyzer responds to a resistance input.
Disconnect the conductivity cell cable and connect a
suitable resistance box directly to the analyzer input - see
section 7.2, page 61. Select the CONFIG. SENSORS
page and and set Temp.Comp. to None - see section 5.3,
page 21. Check the analyzer displays the correct values
as set on the resistance box - see Table 8.2 or use the
expression:
R =
Where:
R = resistance
K = cell constant
G = conductivity
Failure to respond to the input indicates a fault with the
analyzer which must be returned to the Company for
repair. A response, but with incorrect readings, usually
indicates an electrical calibration problem. Re-calibrate the
analyzer as detailed in Section 7.3.
2. If the response in a) is correct, reconnect the conductivity
cell cable and connect the resistance box to the cell end.
Check the analyzer displays the correct values as set on
the resistance box in this configuration. If the analyzer
passes check a) but fails check b), check the cable
connections and condition. If the response for both
checks is correct, replace the conductivity cell.
Error Message
Possible Cause
A: FAULTY Pt100
A: FAULTY Pt1000
Temperature compensator/associated
connections for Sensor A are either open
circuit or short circuit.
B: FAULTY Pt100
B: FAULTY Pt1000
Temperature compensator/associated
connections for Sensor B are either open
circuit or short circuit.
BELOW COMP RANGE
If
Temp. Comp.
is set to
NH3
5.3, page 21), the indicated conductivity
value flashes if the measured conductivity
of the sample falls below the accurate
temperature compensation range.
If accurate readings are required below
this value, set
Temp. Comp.
to
UPW
.
BEFORE CAT. HIGH
The pre-set conductivity value before the
cation resin column has been exceeded -
see appendix A.3 on page 75.
BEFORE CAT. LOW
The conductivity value before the cation
resin column has fallen below the
acceptable value for reliable readings
when inferred pH is selected - see
appendix A.3 on page 75.
AFTER CAT. HIGH
The conductivity value after the cation
resin column has exceeded the
programmed limit - see appendix A.3 on
page 75.
Infr. pH invalid
The calculated (inferred) pH is either:
outside the range 7.00 to 10.00pH if
NH3
temperature compensation (for a
NH3
dosed sample) is selected (see section
5.3, page 21)
or
outside the range 7.00 to 11.00pH if
NaOH
temperature compensation (for a
NaOH
dosed sample) is selected (see section
5.3, page 21)
Note.
In the latter case, the calculation
becomes invalid if the after-cation
conductivity value, multiplied by 3, is
greater than the before-cation value.
Table 8.1 Error Messages
Cell Constant (K)
Conductivity
µS cm
-1
(G)
0.05
0.1
1.0
Resistance (R)
0.055
909.091k
Ω
-
-
0.1
500k
Ω
1M
Ω
-
0.5
100k
Ω
200k
Ω
-
1
50k
Ω
100k
Ω
1M
Ω
5
10k
Ω
20k
Ω
200k
Ω
10
5k
Ω
10k
Ω
100k
Ω
50
1k
Ω
2k
Ω
20k
Ω
100
500
Ω
1k
Ω
10k
Ω
500
100
Ω
200
Ω
2k
Ω
1000
-
100
Ω
1k
Ω
5,000
-
-
200
Ω
10,000
-
-
100
Ω
Table 8.2 Conductivity Readings for Resistance Inputs
K x 10
6
G
