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Calibration or Slope Drift
pH Sensor
Sensor needs deproteinizing/conditioning
Deproteinize/condition sensor, Page 3-7.
Bubbles in fill solution, or insufficient or concentrated fill solution
Debubble sensor, or empty and refill, Page 3-17.
The problem may also be caused by the reference sensor.
pCO
2
/pO
2
Sensor
Sensor needs deproteinizing
Deproteinize sensor, Page 3-7.
Sensor failure (confirm by measurement block routine, Page 4-10)
Replace sensor.
System
Dampness around the sensors
Dry off measurement block and sensors.
Check sensor ‘O’ ring seals and replace if necessary.
Check sensors are seated properly, and the tensioner is pushed
firmly home.
See Pages 3-17 and 3-19.
Partial blockage in sensors
Clear blockage, Page 3-31.
Gas pressure incorrect/gas flow rate incorrect/leaks in gas system/gas
cylinders connected incorrectly
Check gas pressure and flow rate/cure leaks/check gases connected
correctly (cal to cal, slope to slope).
See Page 3-10.
Incorrect gas values entered
Enter correct values, Page 5-2.
Barometric pressure incorrect or changed
Enter correct barometric pressure, Page 2-9.
Calibration or Slope no Endpoint
All calibrations and sample measurements must be carried out with the
front cover lowered.
Reference Sensor (pH no endpoint)
Bubble in reference sensor
De-bubble reference sensor.
Nafion inner is dry due to a large bubble, or not screwed down properly,
or poorly fitting
Place Nafion inner if dry, or refit correctly.
Sensor is clogged with crystals caused by poor filling, or bubbles
creating crystal growth
Empty sensor cassette and refill carefully with reference sensor fill solution.
Vent hole blocked
Unblock the vent hole in the reservoir cap.
Failed membrane
Replace sensor cassette.
See Page 3-19.
Page 4-2
248 Operator’s Manual
Summary of Contents for RAPIDLAB 248
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