Chapter 11
Maintaining a FID
FID Troubleshooting
214
Maintenance and Troubleshooting Manual
FID Troubleshooting
Change in Sensitivity
The sensitivity of the Flame Ionization Detector depends on the carrier and
detector gases flow rates and to the detector temperature.
The gas flow rates must be set correctly for proper FID operation.
Gases
The gases
normally used with FID are reported in Table 11-2.
Table 11-2.
Gases used for FID
Carrier gas
Detector Gas
Make-up gas Gas
Capillary Columns
Packed Columns
Helium
Nitrogen
Hydrogen
Helium
Nitrogen
Argon
Hy
Air
Nitrogen
(recommended)
Helium
The carrier gas flow range depends on the type of the gas used and on the type and
diameter of the capillary or packed column installed.
NOTE
Make-up gas is not required when a packed column is used.
The recommended range of detector gas flow rates tolerated by the FID are
reported in Table 11-3.
Table 11-3.
Recommended flow rates for FID
Gas
Flow rate
Hydrogen
30 - 50 mL/min
Air
300 - 600 mL/min
Make-up gas
10 - 60 mL/min
To gain optimum analytical performance from the FID the hydrogen flow rate
should be experimentally optimized, keeping the carrier and air flows constant, to
obtain the maximum signal intensity for the components of interest.