Varian 450-GC, User Manual

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Detectors – Flame Ionization Detector (FID)
Page: 290 User Manual 450-GC Varian, Inc.
Reassemble the FID
Refer to Figure 45 on page 288 to reassemble the FID detector. To reassemble
the FID, proceed as follows:
1. Re-assembly is the reverse of removal.
2. Install the flame tip in the detector base. The FID and TSD flame tips are
identical.
•
If you are installing the flame tip with a new Vespel/graphite ferrule,
tighten the assembly finger-tight plus an extra 1/6-turn.
•
If you are installing the flame tip assembly with a used graphite
ferrule, tighten about 1/3-turn past finger tight.
3. The Vespel/graphite ferrule supplied with the GC has a maximum
temperature limit of 400 °C. If it is necessary to operate the detector above
400 °C, you may need to replace the Vespel/graphite ferrule with a graphite
ferrule (450 °C).
4. Install a new aluminum seal washer onto the shoulder of the detector base.
To ensure a reliable tower seal, use a NEW aluminum washer each time
you install the detector.
5. Place the detector tower on the detector base and secure it with the 2 tower
mounting screws. Alternately tighten these screws a ½-turn as t he tower
tightens into place.
Handle the ceramic insulator and probes with tweezers to avoid
contamination.
6. Carefully insert the igniter probe into the lower arm of the detector tower.
Align the probe key with the tower arm slot. Check the orientation of the
igniter elements by looking down through the top of the detector tower. The
spring clip should slip around the flame tip and make good contact (see
Figure 46 on page 291). The igniter coil must not touch the flame tip
assembly nor be positioned directly above it. Tighten the knurled nut to
secure the probe.
7. Make sure the notch in the detector tower arm does not cut the O-ring seal.
8. Insert the insulator into the detector tower, then insert the collector tube into
the tower. The collector tube must not touch the igniter coil.