Alarm: Calibration Failure
Manufacturer: Yokogawa
Alarm Description
The Calibration Failure alarm is generated when the analyzer does not reach the expected oxygen value during zero or span calibration. When this alarm is active, calibration results are invalid and measurement accuracy cannot be guaranteed.
When This Alarm Typically Occurs
- During automatic or manual calibration
- After long operation without calibration
- After maintenance on calibration gas lines
Probable Causes (Most Common First)
- Calibration gas not reaching the sensor
- Calibration solenoid valve malfunction
- Incorrect, expired, or wrong concentration calibration gas
- Leak or blockage in calibration tubing
- Slow or degraded zirconia sensor response
Field Checks
- Confirm calibration gas pressure and flow
- Manually activate calibration valves
- Inspect tubing for leaks or blockage
- Verify gas concentration and expiry date
- Observe sensor response during calibration
Corrective Actions
- Restore calibration gas supply
- Replace faulty solenoid valve
- Use correct certified zero/span gas
- Repair or replace damaged tubing
- Replace sensor probe if response is slow
Impact on Measurement
Ignoring calibration failure can result in drifting oxygen readings, unreliable combustion control, and incorrect emissions reporting. Successful calibration is mandatory before returning the analyzer to service.