Decision Tree — Carrier / Pressure / Flow
This decision tree focuses on stabilizing carrier gas pressure and flow. Most GC instability issues originate from carrier supply problems rather than method or detector configuration.
Goal:
Stabilize carrier pressure (no hunting) and eliminate leaks
before changing GC methods or calibration parameters.
Recommended Troubleshooting Sequence
1) Confirm carrier cylinder pressure is adequate and
all isolation valves are fully open.
2) Check regulator stability.
Any pressure hunting or oscillation indicates a faulty regulator.
3) Leak-test all carrier line connections,
manifolds, and fittings using approved leak-detection methods.
4) Verify carrier inlet pressure at the analyzer
is within specification and remains steady over time.
5) Run 2–3 analysis cycles and confirm
peak shape, retention time, and repeatability return to normal.
Technician note:
Never compensate for unstable carrier pressure by adjusting
method parameters. Fix the supply first.