Agilent Technologies 6850 Series II User Information page 205

9.
Checking for gas leaks
The detector is an unlikely leak source. If you suspect that there is a leak in
your GC system and have checked the gas plumbing to the GC, the inlet, and
the column inlet and detector connections without finding it, follow this
procedure to test the detector.
The oven and inlet should be at their normal operating temperatures.
Materials needed:
•
•
To perform this procedure, you will need a control module or data system.
1.
2.
Released: March 2004
At first, the displayed signal will be very high–about 840,000. As clean
gases purge contaminants from the system, the signal should drop to the
baseline level seen before the manifold replacement. As a general guide-
line:
• A new µECD should have a baseline offset < 200 Hz
• Any µECD should have a baseline offset < 400 Hz
• It may take up to 24 hours for a µECD to stabilize
If a detector shows a baseline > 400 Hz after stabilization, there may be
contamination (in the inlet, column, and connections as well as the
detector) or a leak anywhere in the system, or the detector may require
thermal cleaning, maintenance, or replacement. See the GC service
manual for troubleshooting details.
Prep Run
Ready for autoinject
Sig: Detector 846000
Stop
Start
Not Ready
A vent plug (part no. 5060-9055)
An electronic leak detector capable of detecting your carrier gas
Turn off the inlet pressure. Allow some time to purge the system of the
gas.
Turn off the makeup gas flow.
When there is no flow, the output will be at its maximum, which is
approximately 840,000 for both argon/methane and nitrogen.
6850 Series II GC User Information
Maintaining a Microcell Electron Capture Detector (µECD)
Load
Run
Routine Maintenance: Detectors
page 205 of 256