Calibration certificate

A calibration certificate is the document that records the calibration of a measuring instrument against a traceable reference standard, with the date, the readings, the allowed tolerance, and the validity period. On ships it covers cargo and bunker measurement systems: tank gauging and ullage instruments, flow meters, pressure and temperature sensors, and oxygen and gas analyzers, so a draft or volumetric figure can be defended in a quantity dispute. Surveyors, charterers, and terminals require current certificates before they accept a measurement, and an expired or missing certificate undermines the figures and can void a cargo-quantity claim. Calibration is traceable to national or international standards.