Detectors 5
Advanced Operation Manual 203
Helium, either as carrier or makeup gas, may cool the
detector gases below the ignition temperature. We
recommend using nitrogen rather than helium.
Lighting the FPD
+
flame
Before trying to light the flame, heat the detector to
operating temperature and let it stabilize.
During the ignition sequence, the detector does the following:
1 Until the detector temperature zones reach setpoint, the
GC purges the detector with all gas flows.
2 Once the detector stabilizes at its thermal setpoints, the
GC turns off hydrogen and makeup gas flows. Carrier and
air flows remain on.
3 Sets air flow to 500 mL/min.
4 Turns the glow plug ignitor on.
5 Ramps the hydrogen flow from 10 to 70 mL/min.
6 Resets the air flow to the air flow setpoint.
7 Resets the hydrogen flow to the hydrogen flow setpoint.
8 Turns the makeup gas on.
9 Compares the signal change with the Lit offset value. If the
change is greater than Lit offset, declares the flame on
(lit). If it is less, declares the flame off (not lit).
For this process to work, there must be enough air pressure
to the pneumatics module to provide up to 500 mL/min
flow. We recommend a supply pressure of at least 60 psi.
See the Installation and First Startup manual.
Tabl e 53 Recommended flows
mL/min
Carrier (hydrogen, helium, nitrogen, argon)
Packed columns 10 to 60
Capillary columns 1 to 5
Detector gases
Hydrogen 60
Air 60
Carrier + makeup 60
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