Troubleshooting The Npd - Thermo Scientific TRACE GC Ultra Maintenance And Troubleshooting Manual

Chapter 13
Maintaining a Nitrogen Phosphorus Detector

Troubleshooting the NPD

Symptom
No detector response
Detector response lower than
expected
High background level
FID-like response for solvent
and other carbon based
compounds
266
Table 13-4. NPD Troubleshooting Table
Diagnosis
Source heating current too low.
No hydrogen flow.
No air flow.
Source turned off
Source faulty
Lower source temperature
Air contamination in hydrogen
line.
Heating current too high.
Hydrogen flow too high.
Air and/or Make-up gas flow
too low.
Excessive column bleed.
Hydrogen flow too high.
NPD Troubleshooting
Remedy
Increase the heating current.
Turn the hydrogen flow on and
set it to a correct value.
Turn the air flow on and set it
to a correct value.
Turn the source on.
Replace the source
Check the base body
temperature and source heating
current.
Turn the source off. Increase
the hydrogen pressure for 10-
20 minutes to purge the
hydrogen line. Check the line
tightness.
Set the correct operating
parameter.
Set the correct operating
parameter.
Set the correct operating
parameter.
Column conditioning has to be
performed.
Reduce hydrogen flow to a
lower value.
Maintenance and Troubleshooting Manual