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AW T4 20 |
U N I V ER S A L 4 - W I R E , D UA L- I N P U T T R A N SM I T T ER | O I/AW T4 2 0 - EN R E V. B
…16 Troubleshooting
…Diagnostic messages
… pH diagnostics
NAMUR
icon
Diagnostic
message
Cause
Recovery action
S(n):
Process Temp
Out of Range
Solution temperature is outside the
measurement range of the sensor.
Refer to the sensor data sheet to determine
the temperature range.
Ensure that the solution temperature is within the sensor
measurement limits.
Check the process and reduce the effect of any potential heat sources.
If
Process Temperature Out of Range
is consistently active it may be
necessary to replace the sensor with an alternative with a wider, or
more appropriate temperature range. Contact local service
organization for potential solutions.
S(n):
Reference
Warning
The measurements taken from the reference
electrodes indicate that the reference
electrodes are becoming contaminated
(Reference Poisoning).
This is an early indication that the reference
measurement is likely to fail, at which point the
sensor has reached the end of its serviceable
life and requires replacement.
Visually inspect sensor tip for signs of damage or dirt and clean if
necessary.
Contact local service organization to order a new sensor.
S1:
Slope Low
The pH sensor is reaching the end of its
serviceable life.
A pH sensor degrades over time. As this
happens the slope calculated by a calibration
procedure gradually decreases.
A
Low Slope Limit
is configured in
Sensor Setup
– see page <?>.
If the slope calculated by a calibration
procedure is less than
Low Slope Limit,
the
calibration fails.
If the slope calculated by a calibration
procedure is within 20% of the
Low Slope Limit,
the
Low pH Slope
diagnostic is activated
indicating that the sensor is reaching the end of
its serviceable life and soon requires
replacement.
1. Visually inspect sensor tip for signs of damage or dirt and clean if
necessary.
2. Check that sensor tip is fully submerged in the solution.
3. Ensure that the buffer solutions have been made up accurately and
have been correctly selected in the transmitter.
4. Repeat calibration, if Low pH Slope persists then this indicates that
the sensor is reaching the end of its serviceable life.
S(n):
Ambient Temp
Out of Range
The electronics in the head of the probe are
exposed to temperatures outside the
recommended operating range.
Move the sensor to a location where the ambient temperature within
the operating range.
If
Ambient Temperature Out of Range
is consistently active it may be
necessary to replace the sensor with an alternative with a wider, or
more appropriate operating range. Contact local service organization
for potential solutions.
S(n):
Ref. Blocked
The measurement taken from the reference
electrode indicates that the reference electrode
is blocked.
This warning may also occur if the probe is not
properly immersed in solution.
Visually inspect sensor tip for signs of damage or dirt and clean if
necessary.
Ensure pH probe is submersed in solution.
If
Reference Blocked
persists, contact local service organization.
S(n):
Out of Solution
Sensor readings indicate that the sensor is not
properly immersed in process solution.
Visually inspect the sensor for signs of damage and clean the tip if
necessary.
Check that the sensor is properly immersed in the process solution.
If
Out of Solution
persists, contact local service organization.
S(n):
Low Electrolyte
The electrolyte level (in the pH sensor) is low.
If compatible, top up the electrolyte reservoir with liquid electrolyte.
Otherwise contact local service organization.
