Calibration is the comparison of measured values taken from a device under test, with those of a standard of known accuracy, for the purpose of detecting and reporting, or eliminating by adjustment, errors in the instrument tested.
The calibration standard is normally traceable to a national standard held by an accredited National Metrological Institute such as NIST in USA or the National Measurement Institute Australia (NMIA).
The comparison results in either:
- No significant error found on the device under test.
- A significant error being found but no adjustment made.
- A significant error being found, and an adjustment made to correct the error to an acceptable level.
The term calibration means the act of comparison. A compliant calibration does not necessarily include adjustments to bring the instrument up to specified performance. It may only require evidence of performance to within manufacturer’s specification. Note that the results of a calibration have to be written up in a calibration record that lists the calibration points and the correction values at each point with a given uncertainty, determined by the calibration process.
Note that only an accredited metrology laboratory is allowed to produce an official calibration report and only for the scope (parameter and accuracy level of a physical quantity) the laboratory is accredited for.Vacuum calibration and gauge calibration in Sydney.