Detectors 5
Advanced Operation Manual 171
To light the FID flame
Press [Front Det] or [Back Det], scroll to Flame, then press
[On/Yes].
To extinguish the FID flame
Press [Front Det] or [Back Det], scroll to Flame, then press
[Off/No].
FID automatic reignition (Lit offset)
Lit offset is the expected minimum difference between the FID
output with the flame lit and the output with the flame off.
The GC checks this value during runs and when loading a
method.
During a run, if the output falls below the Lit offset value, the
FID will attempt to reignite three times. If after the third
attempt the output does not increase by at least this value,
the detector shuts down all functions except temperature
and makeup gas flow.
When loading a method that includes a Flame On setting, the
GC performs a similar check. If the detector output is less
than the Lit offset, it will attempt reignition after reaching
method setpoints.
The default setting for Lit offset is 2.0 picoamps. This is a
good working value for all but very clean gases and systems.
You may want to lower this setpoint if the detector attempts
to reignite when the flame is still on, thus producing a
shutdown.
Tabl e 43 Unit conversions
Data system Height units LSV (height units) Area units Noise (ASTM)
*
Agilent data system 1 pA 1.3 x10
-4
pA 1 pA-sec 0.038 pA
SIGRange
†
01 x 10
-4
pA 1.3 x 10
-4
pA 1 x 10
-4
pA 0.038 pA
SIGRange 5 3.2 x 10
-3
pA 4.2 x 10
-3
pA 3.2 x 10
-3
pA 0.038 pA
Analog 1V
‡
1.25 x 10
-4
pA device dependent 1.25 x 10
-4
pA 0.038 pA
* Noise is recommended maximum when determining MDL.
† SIGRange used with 3393 and 3396 integrators.
‡ Analog 1V is an approximate value.
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