Troubleshooting
6850
6850
Released: April 2004 6850 Series Gas Chromatograph Service Procedures 334
Loss of sensitivity or excessive drift
Several possible causes exist for overall deterio-
ration of the chromatogram.
• Contamination in the valve requires a thor-
ough cleaning.
• Internal leakage requires a complete disas-
sembly and inspection of the mating sur-
faces.
• Poor temperature control may require a full
check of electronic and thermal components.
• Lack of proper conditioning techniques, col-
umns, etc.
• Failure or deterioration of other components
(columns, detectors, etc.).
Loss of peaks in specific areas of the
chromatogram
Entire sections of chromatographic data can be
lost due to a valve that does not rotate or one
that rotates improperly. Other than obvious
component failures (solenoid, actuator, etc.),
improper adjustments and misalignments cause
most problems.
• Check that adequate air (about 482 kPa or
70 psi) is supplied.
• Check the valve. Is it rotating?
• If the valve rotates, check for proper align-
ment of the actuator, mechanical binding or
slippage of connecting parts.
• Check for blocked flow paths with valve in
both positions.
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