Flame Ignition Problems - HP 5890 Series II Plus Reference Manual

Detector Systems
Flame photometric detector (FPD)

Flame ignition problems

Two common flame ignition problems are:
A loud pop results on ignition and the flame will not light or stay lit.
If a loud pop occurs on ignition, it is usually caused by an incorrect
ignition sequence. The correct ignition sequence is:
1. Open the auxiliary Nitrogen Valve if required.
2. Open the Air/Oxygen Valve fully counterclockwise (CCW).
3. Press in and hold the Ignitor Valve.
4. Open the Hydrogen Valve fully counterclockwise (CCW). On doing
this, there should be a slight pop.
Note: A loud pop is caused by opening the hydrogen valve before
pressing the ignitor, thereby igniting a volume rich in hydrogen. This
should not damage the detector but is unpleasant to hear. Always open
the hydrogen valve after pressing the ignitor.
If the FPD flame won't light or stay lit, check/do the following:
1. Be sure there is a problem. Under some conditions, the flame lights so
quietly that the pop is nearly inaudible. Also, especially in oxygen
mode, the increase in signal offset on the LED display is usually only
a few counts. Flame ignition is best verified by holding a mirror or
shiny surface near the aluminum exhaust tube (with the rubber drip
tube removed) and observing condensation (if the flame is lit).
2. If the flame doesn't light at all, be sure the glow plug circuit is
working. This is most easily done by observing the LED display,
which should go to greater than 65500 counts when the ignitor switch
is pressed. If the LED display doesn't change with the ignitor switch
pressed, either the circuit is open (check the pin connections at the
detector flow manifold block, the lead connection on the glow plug,
and the appropriate 5A fuse on the instrument's main circuit board).
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