Decision Tree: Valve / Sequence
Goal: ensure valves switch correctly and method timing is consistent (valve faults can look like “no peaks”).
1) Check instrument air supply (if used): pressure OK, clean/dry, no water/oil.
2) Observe valve actuation (sound/indicator). If no actuation: check solenoid power + wiring.
3) If actuation OK but results wrong: suspect sticking valve, contamination, or internal leakage.
4) Confirm method/sequence timing matches last known good configuration.
5) After correction: run 2–3 cycles and verify repeatable peaks and stable retention time.
Quick Symptoms → Likely Cause
No peaks + valve alarm: air supply missing, solenoid/power/wiring fault.
Peaks wrong order: timing mismatch, valve leakage, wrong switching.
Repeatability poor: sticking valves, contamination, unstable pressure.