Why it matters
Drift silently invalidates fixed thresholds. A detector that read 200 in clean air when installed and reads 280 two years later has moved its own alarm point without anyone deciding to.
Sensing
Sensor drift
Sensor drift is the gradual change in a sensor's output over time for an unchanged input, caused by ageing, contamination or environmental exposure.
How it works
Chemical sensing elements degrade as their active material is consumed or poisoned. Compensation involves periodic recalibration, or expressing readings relative to a recaptured baseline rather than in absolute terms.
Example
An gas-sensing element in a dusty workshop reads progressively higher in clean air as its surface contaminates.
In Alfa HazardX
Percent-over-baseline metrics reduce drift sensitivity, and re-capturing a baseline is the intended mitigation. Automatic drift detection is not implemented.
Read further
Related terms
- Sensor burn-inBurn-in is an initial powered period a sensing element requires before its readings become stable and trustworthy.
- Baseline deviationBaseline deviation measures how far a current reading has moved from what is normal for that specific sensor in that specific location.
- Cross-sensitivityCross-sensitivity is a sensor's tendency to respond to substances other than the one it is intended to measure.