Emerson Rosemount 700XA Reference Manual page 84

3. Loosen the screws holding the solenoid in place and remove the solenoid.
4. Place a small amount of silicone grease on the target device (pneumatic block, four-way stream block, etc.) where the
solenoid is to be placed.
The grease ensures a tight seal.
5. Tighten the screws to hold the solenoid in place.
6. Place the oven upright.
7. Tighten the ultem thumb screw.
Repairing and maintaining the detectors
When a thermal conductivity detector (TCD) fails to perform normally, you may need to replace it.
Signs that a TCD may be faulty include, but are not limited to, the following:
■ A chromatogram with a wandering or drifting baseline
■ A chromatogram with a noisy baseline
■ A chromatogram with a no peaks
■ No chromatogram
A test for a faulty TCD involves measuring the resistance of each filament using a multimeter. A pair of thermistors should give the
same resistance reading; therefore, if a thermistor reading is significantly different from the reading of its mate, replace the pair.
Otherwise, the TCD bridge will be unbalanced, noisy, and drifty.
Required tools for thermal conductivity detector (TCD) maintenance
A flat-head screwdriver is required for removing and replacing TCDs. Use a multimeter to test the thermistor pair.
Thermal conductivity detector (TCD) replacement parts
Consult the parameter list that was provided with the gas chromatograph (GC) for the thermistor kit required to replace one TCD. A
new thermistor seal (2-6-5000-084) is also required.
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July 2020
Emerson.com/Rosemount