There are situationswhere it would
be
helpful to op–
erate the FlOdetector using just the built-in air com–
pressor for carrier gas and no other gases. SRI dis–
tributors demonstrating the GC and softwaremay
find it useful to run live chromatograms without the
inconvenienceof providing hydrogen and helium.
Service personnel troubleshooting other GC func–
tionsmay be able to test the GCwithout gases, and
under some circumstances, the response of the
f1ameless ionization detector ( FLiO )may actually be
useful for non-quantitative appl ications.
The FlOdetector is normally locatedon the right
hand sideof the column oven.
The FlOnormally requires a
flow
of 20-30 mVminof
. hydrogen and 200-300mVminof air to support a hy–
drogen flame at the tip if the jet. The heat of the
flame ionizes the analytemolecules, and the nega–
tive ions allow a small electric current to flow
be–
tween thecollector electrode and the grounded flame
jet. The ignitor normally serves only to ignite the
flame.
The FlOdetector body is shownat right in the normal
configuration, but removed from thedetector heating
block on theGC for clarity.
Inside the FlOdetector body, the ignitor is normally
positionedjust belowand behind the tipof the jet.
Notice that the ignitor blade is tilted at a 15 degree
angle from the ceramic tube inwhich it is fabricated.
In normal FlOoperation, the ignitor is positioned
be–
low and behind the jet so it will not disrupt or distort
the flame, yet close enough to easily ignite the hydro–
gen/airmixture.
Manl43.pub
