Agilent Technologies 6890 Series Service Manual page 36

Gas chromatograph

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Calibration Notes

Calibrating the 6890 GC

to access a list of the 6890 Series GC parameters that can be calibrated.

Calibration options

The following GC parameters can be calibrated:

The GC oven temperature can be corrected to actual measured

temperature.

We do not recommend field calibration of flows and pressures, other than

zeroing. A full calibration requires establishing flows and pressures that

are comparable in accuracy to the NIST-traceable factory equipment.

Flow sensors can be zeroed. The Auto flow zero function, when turned

on, automatically zeroes flow after each run. To use this feature, select

Calibration on the OPTIONS menu, then choose either Front inlet or

Back inlet, and turn Auto flow zero on. After the end of a run, Auto

flow zero shuts down the flow of gases to an inlet, waits for the flow to

drop to zero, measures and stores the flow sensor output, and turns the

gas back on. This takes about two seconds. The zero offset is used to

correct future flow measurements.

Pressure sensors can be zeroed by fully depressurizing the system, inlets

or detectors. Open appropriate fittings to ensure that there is no residual

or trapped pressure, then select Pressure Zeroing and press the On

Capillary columns can be calibrated. Length and internal diameter can

be estimated using data from an isothermal run. This is useful when such

data were not provided with the column or if trimming has reduced the

length of the column.

Additional information regarding each individual inlet, detector, make–

up gas or Aux Pressure/Flow Calibration Ranges can be obtained by

scrolling to the task and pressing the Info key. Typically a calibrated

flow of greater than 50% of the EPC module's flow range is required to

calibrate. A pressure greater than 70% of an EPC pressure range is

required to calibrate it.

Options] key on the GC keypad and select the Calibration option

Before Servicing the Instrument

Agilent 6890 Gas Chromatograph Service Manual

Troubleshooting

6890a 6890 plus