Stability

Stability describes how well an instrument holds its calibration over time. A highly stable instrument maintains consistent performance between calibrations, while an unstable instrument may drift significantly, requiring more frequent calibration or producing unreliable measurements as it departs from its calibrated state.

Stability is assessed by examining trends in as-found calibration data over multiple calibration cycles. If the as-found readings remain consistently within tolerance and show no systematic trend, the instrument is considered stable. If the readings gradually move toward or past the tolerance limits, the instrument exhibits instability. Stability can also be evaluated through intermediate checks performed between scheduled calibrations.

For calibration management, stability directly influences the optimal calibration interval. Stable instruments can safely go longer between calibrations, reducing costs and downtime. Unstable instruments need shorter intervals to ensure they remain within tolerance. Reliability-centered calibration approaches use historical stability data to statistically optimize intervals, balancing the risk of out-of-tolerance conditions against calibration costs. Environmental factors like temperature swings, vibration, and humidity can degrade stability, making proper storage and use conditions important.