Varian 450-GC, User Manual

Page: 136 / 205

Detectors – Flame Ionization Detector (FID)
Page: 286 User Manual 450-GC Varian, Inc.
DO NOT look directly into the detector tower
when attempting to ign ite the flame.
You can verify that the flame is lit by monitoring the FID signal in the
status region of the FID display.
Uncheck the box “AutoZ.” and press “Clear AutoZ.”
Initially the signal will read a very high value but should then stabilize.
Typically the signal will be > 50 mV at range 12 when the flame is first
lit but should drop to < 10 mV within 30 minutes.
To avoid a possible fire or explosi on, always tu rn
off the flow of hydrogen when the column is
removed or when the detector i s not being used.
This prevents the accumulation of hy drogen.
3. Set the Time Constant to “Fast”. The default setting for the time
constant is “Fast”.
Fast time constant: - Used with capillary columns.
- Reduce high frequency noise.
- Used for narrow peaks.
Slow Time Constant: - Used with packed columns.
- Used for broad peaks.
4. The “Ignite” button applies power to the FID igniter filament for 5
seconds.
5. The “Autozero” button applies an immediate zeroing of the detector
signal.