ZR22G — Calibration Failure (Decision Tree)
Use this when the analyzer rejects calibration, won’t stabilize, or span/zero won’t reach target.
Golden rule: Do not calibrate until the reading is stable and the heater/reference air are OK.
Calibration failure is usually caused by unstable sensor temperature, bad reference air, or leaky calibration setup.
Decision Tree
1) Warm-up / Heater OK?
If heater alarm exists or temperature not stable → go to Heater Error page and fix heater first.
If heater alarm exists or temperature not stable → go to Heater Error page and fix heater first.
2) Reading stable in process?
If O₂ reading fluctuates heavily → fix stability first (probe fouling, reference air, leaks). Do not calibrate yet.
If O₂ reading fluctuates heavily → fix stability first (probe fouling, reference air, leaks). Do not calibrate yet.
3) Calibration gas correct and flowing?
Confirm cylinder concentration matches the procedure, regulator OK, flow sufficient, no blocked tubing.
Confirm cylinder concentration matches the procedure, regulator OK, flow sufficient, no blocked tubing.
4) Leak check calibration line
Apply soap test / pressure hold test on tubing, fittings, manifold. Any leak → fix and retry.
Apply soap test / pressure hold test on tubing, fittings, manifold. Any leak → fix and retry.
5) Reference air OK?
Ensure clean/dry reference air path (filter not clogged, tubing not kinked, flow present). Blocked/leaky reference air causes calibration failure/drift.
Ensure clean/dry reference air path (filter not clogged, tubing not kinked, flow present). Blocked/leaky reference air causes calibration failure/drift.
6) Probe / filter condition
If dust/ash buildup or plugged filter cap → clean/replace. Plugging causes slow response and “no stabilize” during cal.
If dust/ash buildup or plugged filter cap → clean/replace. Plugging causes slow response and “no stabilize” during cal.
7) Stabilization time sufficient?
Allow enough time after switching gas. In dusty service, stabilization may take longer.
Allow enough time after switching gas. In dusty service, stabilization may take longer.
8) Still failing?
Suspect sensor aging, damaged cell, wiring issues, or incorrect setup parameters (range/units). Record diagnostics and escalate.
Suspect sensor aging, damaged cell, wiring issues, or incorrect setup parameters (range/units). Record diagnostics and escalate.
Field tip: If span gas cannot reach target, 80% of cases are cal gas leak/flow issue or probe blockage.
Quick Checks (Before Re-Cal)
- Heater status normal, temperature stable
- Reference air clean/dry, filter OK, no leak
- Calibration gas correct concentration & flow
- No leaks in calibration tubing/manifold
- Probe tip/filter cap clean