Decision Tree: Valve / Sequence
Goal:
Ensure valves switch correctly and
method timing is consistent.
Valve faults often appear as
“no peaks” or “wrong peaks”.
1) Check instrument air (if used):
pressure OK, clean/dry,
no water or oil,
regulator stable.
2) Observe valve actuation
(sound or indicator).
If no click or movement,
check solenoid power and wiring.
3) If valve clicks but results are wrong:
suspect sticking valve,
contamination,
or internal leakage.
4) Confirm method sequence timing:
compare with the last known
good method (if available).
5) After correction,
run 2–3 cycles
and verify repeatable peaks
and stable retention time.
Quick Symptoms → Likely Cause
No peaks + valve alarm: no actuation (air, solenoid, power, or wiring).
Peaks present but wrong order: method timing issue or valve leakage.
Unstable area / repeatability: sticking valve, contamination, or pressure instability.