pH Analyzer – Alarm Decision Tree (Generic)
This decision tree helps technicians troubleshoot common pH analyzer alarms logically and efficiently. Follow the order strictly to avoid unnecessary sensor or transmitter replacement.
Golden rule: pH alarms almost always originate from the
sensor or process, not from the analyzer electronics.
Alarm: Unstable / Noisy pH
- Check sensor: air bubbles, loose mounting, cracked glass.
- Check process: turbulence, flashing, intermittent flow.
- Check grounding: poor grounding causes noisy signals.
- Check cable: moisture ingress, damaged insulation.
Do not recalibrate before stabilizing the signal.
Alarm: Drifting pH
- Reference poisoning: sulphides, proteins, heavy metals.
- Blocked junction: slow electrolyte exchange.
- Aging glass: slope degradation.
- Temperature mismatch: faulty or slow temperature element.
Frequent calibration = sensor near end of life.
Alarm: Calibration / Slope Failure
- Old or contaminated buffers: always use fresh buffers.
- Insufficient stabilization time: wait patiently.
- Dry sensor: rehydrate or replace.
- Slope outside limits: sensor replacement required.
Calibration cannot fix a damaged sensor.