Siemens RAPIDLAB 248, Operator'S Manual, Page: 78 / 135

Calibration or Slope Outside Range
Reference Sensor (pH outside range)
Bubble in reference sensor
Debubble sensor.
Nafion inner is dry due to a large bubble, or not screwed down properly,
or poorly fitting
Replace 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.
pH Sensor
Sensor needs conditioning
Condition sensor, Page 3-7.
Bubbles in fill solution, or insufficient or concentrated fill solution
Debubble sensor, or empty and refill, Page 3-17.
Sensor failure (confirm by measurement block routine, Page 4-10)
Empty and refill sensor. If problem is not solved, replace 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
Measurement block assembly and sensors are wet
Dry off sensor block assembly 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.
Worn pump tubing
Replace tubing, Page 3-13.
Gas pressure/gas flow rate incorrect/leaks in gas system/gas cylinders
connected incorrectly
Check pressure and flow rate/cure leak/check gases connected
correctly, Page 3-10.
Page 4-4 248 Operator’s Manual