Calibration is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device. The device with the known or assigned correctness is called the standard. The second device is the device under calibration.
What is Traceability?
To improve the quality of the calibration and have the results accepted by outside organizations it is desirable for the calibration and subsequent measurements to be “traceable” to the internationally defined measurement units. Establishing traceability is accomplished by a formal comparison to a standard which is directly or indirectly related to national/International standards (such as NIST in the USA, UKAS in UK and NABL in India).
Why is Calibration required?
Calibration defines the accuracy and quality of measurements of the device under calibration. Over time there is a tendency for results and accuracy to ‘drift’ particularly when using particular technologies or measuring particular parameters more regularly. To be confident in the results being measured there is an ongoing need to service and maintain the calibration of equipment throughout its lifetime for reliable, accurate and repeatable measurements.
The goal of calibration is to minimise any measurement uncertainty by ensuring the accuracy of test equipment. Calibration quantifies and controls errors or uncertainties within measurement processes to an acceptable level.