calibrations

Calibrations are procedures used to determine and improve the accuracy of measurement instruments by comparing their outputs with a reference standard. The aim is to ensure readings correspond to defined values within stated uncertainties and to establish traceability to national or international standards.

The calibration process typically involves selecting an appropriate reference standard, exposing the instrument to known quantities over its operating range, deriving correction factors or calibration functions, and documenting the results in a calibration certificate. Key concepts include traceability, measurement uncertainty, environmental conditions, and instrument drift. Calibration is often distinguished from verification: calibration adjusts the device to meet specifications, while verification checks that it remains within tolerances without adjustment.

Calibration frequency depends on the instrument’s stability, usage, criticality, and regulatory requirements. Environmental factors such as temperature, humidity, and vibration can affect results and may be controlled or noted during calibration. An uncertainty budget is used to quantify the overall measurement uncertainty.

Standards and bodies relevant to calibration include ISO/IEC 17025 and ISO 10012, as well as national organizations such as NIST. Applications span laboratories, manufacturing and process control, aerospace, healthcare, and consumer electronics.

Common calibration types cover sensors and instruments across domains, including temperature, pressure, electrical, and dimensional measurements, as well as end-to-end calibrations for systems. The outcome is typically a calibration certificate that lists instrument details, reference standards, methods, measured values, any adjustments made, the reported uncertainty, and the next due date for calibration.