Chapter 7 87
Troubleshooting
Increase the ignitor current to a
higher value (maximum is 3.3 A)
and reset it to 3.1 A after a regular
pulse is achieved.
Decrease the hydrogen to air ratio.
Secure the PMT housing to the PMT
mounting on the detector body with
the supplied thumbscrew.
Replace the PMT housing.
Verify that the proper PMT and
filter(s) are being used for the
desired analysis and that the filter is
not loose. If loose, add an extra O-
ring.
Lower the HV setting.
Secure the ignitor cap.
Adjust trigger level.
Bakeout the PFPD overnight at
350°C and observe if the noise has
reduced. If the noise is not reduced,
replace the combustor.
The PMT may be exposed to
ambient light, or the PMT has been
damaged and needs to be replaced.
Reset the autozero via the Board/
Channel Parameters window in
WinPulse.
Reduce the PMT voltage.
Examine the emission profile for
response due to contamination.
Replace the combustor if necessary.
Verify that the output signal zero is
enabled.
Check that hydrogen-air ratio is
correctly optimized and that the
range value is correctly set.
Check gate values and filter-PMT
combination.
PROBABLE CAUSE
Ignitor current is set too
low
Hydrogen is set too high
PMT seal is not properly
made
Cracked/deformed PMT
housing
Filter(s) is incorrectly
installed
HV is too high
Ignitor cap is not properly
sealed
Trigger level is improp-
erly set
Combustor is contami-
nated
Severe light leak
Output signal zero is set
at an inappropriate level.
High gain in the PMT
High contamination
An improperly set output
signal zero.
Improper gas flows
Improperly set gate values
CORRECTIVE ACTIONSYMPTOM
PFPD quits pulsing
when solvent is
injected and does
not restart after
solvent elutes
Noisy detector
PMT voltage stays
at 0 V
Negative baseline
High baseline
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