Chapter 15
Maintaining a Photoionization Detector
PID Troubleshooting
334
Maintenance and Troubleshooting Manual
PID Troubleshooting
Sensitivity
Lamp
The most common cause of loss of sensitivity is condensation of the effluent on
the lamp window, resulting in a progressive increase of absorption of the UV. For
long life, the window must be cleaned periodically according to the operating
sequence described in the
Operating Sequence on
A
Lamp failure
message will be displayed when the lamp does not work. One
of the possible causes is the breakdown of the lamp. In this case replace the lamp
following the instructions reported in the in the
Operation
Sequence on page 319.
Contamination
An abnormally high baseline may indicate contamination of the detector. In this
case, turning off the lamp will not make the symptom disappear. This means that
the detector cell has been contaminated.
Try to solve the problem by baking the cell for two hours at 400°C.
If the symptom does not disappear, contact your customer support organization.
Refer to Appendix B,
, for contact information.
If you suspect contaminants are carried into the detector cell by the gas lines, try
reducing the flow rate in each line, one at a time, to identify the contamination
source.
To avoid detector contamination install gas filters between the gas cylinders and
the detector and replace them periodically.
NOTE
To face more effectively possible chromatographic problems, you should carry out an
analysis using the test mixture and evaluate the results.
