Evaluate The Makeup Side - Agilent Technologies 6890 Series Service Manual

Gas chromatograph

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the bottom of the hex of the makeup gas adapter. The measurement should

be 19 to 20 mm. If it exceeds 22 mm, the adapter is installed incorrectly.

A ridge inside the cell can prevent the adapter from easily seating all the way.

Wiggle the adapter while installing to allow it to go all the way in. Always

check the nut to hex measurement to be sure.

Evaluate the makeup side

Remove the makeup adapter from the detector. Unscrew the tip and

remove the Gigabore liner. Inspect the adapter body for carbon (graphite)

deposits. Remove all graphite deposits and clean the adapter thoroughly

with methanol. Soak the removable tip in methanol.

Reassemble the adapter without the gigabore liner. Install a 5-inch length

of narrow bore column, capped with a new septum, so that the other end

extends 1 mm past the tip of the adapter. Use a Vespel column ferrule

rather than graphite. Tighten the tip just past finger tight with clean

pliers. Clean the whole assembly with methanol before installing.

Install the capped-off makeup adapter, using a new 1/4-inch Vespel

ferrule. Be sure it is fully seated—check the measurement. Retighten after

the detector has been heated.

Set the makeup flow to the original setpoint and bake out the detector at

350°C for 1 hour. During this time, put the inlet in split mode with 200

to 300 mL/min split vent flow (gas saver off) and bakeout the inlet at

275°C. Bakeout the column at its appropriate temperature.

When bakeout is done, do not reconnect the column to the detector. Make

a series of blank runs with the user's method. If the baseline is

acceptable—free of peaks and humps and under 1000 Hz throughout a

temperature program—then the detector and makeup system are clean.

Any unacceptable baseline problems could indicate contaminated

makeup gas, EPC module, makeup adapter, or detector. These must be

addressed before continuing.

Troubleshooting contamination problems

Agilent 6890 Gas Chromatograph Service Manual

Electron Capture Detector (ECD)

6890a 6890 plus