Siemens RAPIDLAB 248 Operator's Manual page 77

Troubleshooting the System
Calibration or Slope No Endpoint
pH Sensor
Sensor needs deproteinizing/conditioning
Bubbles in fill solution, or insufficient or concentrated fill solution
The problem may also be caused by the reference sensor.
pCO
Sensor needs deproteinizing
Sensor failure (confirm by measurement block routine, Page 4-10)
System
Dampness around the sensors
See Pages 3-17 and 3-19.
Partial blockage in sensors
Gas pressure incorrect/gas flow rate incorrect/leaks in gas system/gas
cylinders connected incorrectly
Bubble in sample path - specifically under the reference sensor
Very occasionally worn pump tubing may cause instability on one or
more channels
Very occasionally, dampness around the pre-heater, or at the insulating
bushes at either end of the sample path may cause instability
Deproteinize/condition sensor, Page 3-7.
Debubble sensor, or empty and refill, Page 3-17.
/pO Sensor
2 2
Deproteinize sensor, Page 3-7.
Replace sensor.
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.
Clear blockage, Page 3-31.
Check gas pressure and flow rate/cure leaks/check gases connected
correctly, Page 3-10.
Repeat measurement and watch the solution being aspirated to
determine the cause of the bubble.
Replace tubing, Page 3-13.
Clean/dry areas carefully.
Page 4-3