88 Model 5380 PFPD Operator’s Manual
Rev. 3.1
PROBABLE CAUSE CORRECTIVE ACTIONSYMPTOM
The detector response is
exceeding the PFPD’s or
data system’s signal
handling capacity
The range setting for the
signal is set too low
The output signal zero
offset is set too low
Analyte concentration is
too high for the column
The output signal zero is
set too high
There is insufficient PMT
voltage (gain)
Excess flow through
combustor
Low PMT voltage
Incorrectly set gates
Contaminated combustor
Wrong filter
Improper gas flows
Reduce electrometer gain by
reducing the PMT voltage (if
necessary), and increase attenua-
tion value (normally set to 1).
Increase the range setting.
Reset the zero value.
Use split injection to reduce
analyte concentration.
Reset the output signal zero via
WinPulse.
Optimize PMT voltage for noise
measurements (see Appendix D
for details).
Adjust needle valve to tick-tock
operation. Back off Q/r to Q/w turn.
Increase PMT voltage setting (50
V higher) and monitor the noise. If
noise remains the same, continue
increasing the PMT voltage until
the noise level increases (doubles
the initial noise measurement).
Rerun the analysis. If the signal
response increases proportional to
the noise, reset the PMT voltage to
the original optimized noise level.
Check gate start and stop times to
ensure that they are set correctly
for maximum selectivity, and
check threshold (trigger) level for
proper sensing of the propagating
flame event.
Bakeout the PFPD overnight at
350°C and observe if the noise has
reduced. If the noise is not
reduced, replace the combustor.
Verify that the correct filter is
being used with the PMT.
Verify that the H
2
and Air 1 flow
are optimized.
Truncated peak tops
Truncated peak
bottom
Low sensitivity
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