Quantifying Water Vapor Diffusion across Elastomer Pressure Sensor Seals
Water vapor diffusion across elastomer seals causes reference cavity pressurization and dielectric drift, requiring coulometric ISO 15105-2 verification.
Full Scale Accuracy
Uncertainty Specification
Instrument performance is characterized by the maximum deviation from a reference value across the entire measurement range. The full scale accuracy parameter represents this threshold, expressed as a percentage of the sensor’s maximum capacity. This error remains constant in absolute terms regardless of the magnitude of the measured signal.
For example, a hundred-bar sensor with a tolerance of one percent can vary by one bar at any reading.
Calibration Reference
Laboratory certification of a sensor requires comparing its output against primary standards at multiple increments. During this procedure, the full scale accuracy is validated by recording deviations at both the zero point and the upper limit. These measurements verify that the non-linearity and hysteresis remain within the allowable margin.
Measurement Drift
Environmental factors can cause the output of a sensor to wander over time. When temperature variations occur, the full scale accuracy can degrade because of thermal sensitivity shift. Regular re-calibration is necessary to adjust the gain and restore the performance of the instrument.
Field Operation
Practical applications often require operating sensors well below their maximum limits. In these situations, relying on full scale accuracy can lead to high relative uncertainty for small signals. If a sensor operates at ten percent of its capacity, a one percent full-scale error translates to a ten percent error of the actual reading.
This limitation means that engineers must select transducers with measurement ranges that closely match the expected operating forces.