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FPD - flame photometric detector
Troubleshooting
Cause
Observation: FPD is cold:
Heater is turned off
Heater or temperature sensor
not connected correctly
Fuse, heating cartridge, Pt100
or heater control element faulty
Observation: flame does not ignite
Combustion gas and
combustion air connections are
reversed or the flow rates are
incorrect
Air-poor mixture does not
ignite properly
Ignition spark does not jump
from the ignition electrode to
the nozzle
Are 24 V pulses applied to the
amplifier terminals?
Exhaust gas nozzle is blocked
Nozzle is broken
Nozzle is incorrectly adjusted
Observation: basic current is too high
Light enters the detector
Detector temperature is too high Set lower detector temperature
Observation: baseline is unstable
Damping set too low. Detector
is faulty: instability disappears
without flame
Signal cable defective:
instability even without flame
Observation: baseline drifts
if the oven temperature is increased
Column evaporates too much
FPD - flame photometric detector
4 - 26
Remedy
Switch on the heater
Connect the cables correctly.
See Register 9
Replace faulty part
Connect correctly or adjust
correct flow rates, correct leaks
if necessary
Reduce H
pressure before
2
igniting, then reset old value
Adjust ignition electrode
correctly. Check insulation of
ignition cable (also in ignition
module)
- Yes: check/replace ignition
module
- No: replace amplifier
Clean exhaust gas nozzle
Replace nozzle
Adjust nozzle
Assemble detector and
photomultiplier so that no light
can enter, close oven
Set a higher damping
Check as with a high basic
current.
Remove insulation from signal
cable and connect
Select lower oven temperature
Cause
Observation:
baseline drifts at stable temperatures
Is drift less without carrier gas?
- Yes: column is contaminated
- No: deposits in foot
and nozzle of detector
Column is contaminated by
higher boiling components
Cylinder pressure < 5 bar or
gas(es) contaminated
Observation: noise
Damping is too low:
amplitude up to 4 pA with
damping 0
Basic current is higher
than 100 pA
- Detector temperature too high
- Multiplier is too hot (>40 °C)
Recorder oscillates
Observation: spikes and/or offsets
appear in chromatogram
If the spikes disappear when
the signal cable is unplugged,
fine dust is present in the gas
paths or condensation in the
exhaust gas path
If the signal cable reacts to
shock, it is faulty or incorrectly
connected
Pressure regulator is sensitive
to shock
- Spikes without offset
are normal
- Spikes with offset: the
pressure regulator is faulty
The working environment is
not vibration-free
If an offset without spikes
occurs when switching over the
range: this is normal
Observation:
step recording in chromatogram
Attenuation and range do not
match
Recorder is incorrectly set
Remedy
- Replace column
- Heat detector overnight
Replace column
Change cylinder immediately
Enter higher damping
Normal when operating
without column
Set higher attenuation
- Select lower detector
temperature
- Improve cooling
Adjust recorder damping
Burn out pipes, heat detector
Reconnect cable. Replace bent
or crushed cable
Repair or replace faulty
pressure regulator
Create vibration-free working
environment
Select smaller range or larger
attenuation
Set recorder to 0 to 20 mA
EXFPD.CHP
Stand September 14, 1999
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