Agilent Technologies 6890 Series Service Manual page 150

Gas chromatograph

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Set the pressure to 25 psi.

Scroll to Pressure and enter "25" in the "Pressure" field.

Wait approximately 15 seconds for equilibration.

If pressure cannot be achieved, either a very large leak is present in the

system, or the supply pressure is not high enough.

Turn the inlet pressure "Off."

Press [Front Inlet] (or [Back Inlet]), scroll to the "Pressure" field,

and press [Off]. Both the flow controller and the back pressure valves

When the inlet pressure or flow is turned off, the safety shutdown feature,

including the audible alarm, is not functional. The inlet will not automatically

shut down. This will provide you with unlimited time to locate leaks.

Note the "Actual" reading on the display and monitor the pressure for

You can use the stopwatch feature of the 6890 GC to monitor the time.

Press [Time] and then [Enter] to start timing, then toggle between the

time and the pressure reading with the [Time] and the [Front

Inlet]/[Back Inlet] keys.

When the system is considered leak tight, the caps may be removed, the

column reinstalled, its dimensions configured at keyboard, and the

desired pressure and flow rate set.

Programmed Temperature Vaporization Inlet (PTV)

If there is less than 0.5 psi pressure loss, consider the system leak

If pressure loss is much greater than 0.5 psi, there is a leak that must

be found and corrected. Note, however, that you may want to slightly

decrease the leak test time based on the internal inlet volume which

changes with the liner type used (smaller volumes = shorter

acceptable leak test times). See Correcting leaks later in this section.

Agilent 6890 Gas Chromatograph Service Manual

Leak testing

Troubleshooting

6890a 6890 plus