Agilent Technologies 6850 Series II User Information page 64

Table 18. FID Checkout Conditions (Method FIDCKO) (Continued)
Oven
Initial temp
Initial time
Rate 1
Final temp
Final time
Rate 2
Final temp
Final time
Background offset checks
1.
2.
3.
4.
Released: March 2004
If lit, turn the FID flame off.
Display the signal output to determine flame-off background offset. A
stable value of < 2.0 display units is acceptable. If > 20 display units, clean
the detector as described in
(FID)" on page 187.
Ignite the FID flame. You should see an increase in detector output to a
stable value.
If not, hold a cool, shiny metal object, such as a chrome-plated wrench,
just above the FID chimney. You will see water condensation if the flame
is lit.
If the flame has not ignited, recheck all flow rates and gas source pres-
sures. If the flame still cannot be lit, see
light" on page 188 for more information.
With the flame lit, observe the FID signal at the display. This is the
flame-on background offset. A stable value between 5 and 20 display units
is acceptable. If an air cleaning system is being used, the signal may
stabilize below 5.
If the value is > 20 display units, system bakeout is necessary. See
"Thermal cleaning (bakeout)" on page 185
If the value is < 5 display units, verify that the electrometer is on. If it was
off, recheck the flame-off background offset. If it was already on, your
detector requires service.
6850 Series II GC User Information
40°C
0 min
25°C/min
90°C
0 min
15°C/min
170°C
2 min
"Maintaining a flame ionization detector
Verifying Performance
"The flame goes out or will not
for details.
FID checkout
page 64 of 256