Chromatographic Troubleshooting
Locating leaks
Extraneous peaks
Air peaks are sometimes seen in a chromatogram when leakage occurs because the valve rotor does not seal properly. These leaks may not be detectable by using the soap•bubblemethod. The leak test procedure is described in the Site Prep and Installation Manual.
If a leak is suspected but cannot be located with soap bubbles, a pressure check will determine definitely if a leak exists. Extraneous peaks can occur sometimes due to improper conditioning of the valve or contamination. If leaks are not apparent, clean or condition the valve.
Obviously other causes, totally unrelated to the valve, may exhibit similar symptoms. Impure (i.e., containing water) carrier gas can cause extraneous peaks.
Locating leaks
Leak•checkingthe plumbing involved in a valve configured system must be done carefully and methodically. Several methods may be used, and the best choice will depend upon expediency, accessibility, and the magnitude of the leak. Refer to Setting initial supply pressures and leak•testingin the Site Prep and Installation Manual for details.
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