Calibrations

Correct measurements

Calibration is the way to determine errors in the indications of system and measurement instruments and the values of measurement samples so as to guarantee precise and reliable measurement results.

Calibrations are done by comparing the indications of an instrument or the value represented by a sample with the measurement of corresponding known values with the relative uncertainties.

The calibration process of instruments and samples performed by an accredited laboratory according to ISO/IEC 17025 consists of a comparison with a reference sample of a higher level, permitting the measurements produced to acquire the fundamental properties of metrological traceability with respect to national or international samples.

The outcome of the comparison may be stated on the calibration certificate by means of a declaration, a mathematical formula, a diagram, a curve or numerical chart and it can be used to correct the indication of the instrument or to give a value to the characteristics of the material sample.

Calibrations can be performed both by independent laboratories offering their services on the market, and by internal laboratories in a company which can guarantee the quality of their production process.

The objectives

Calibration determines the metrological characteristics of a measurement instrument or sample in the state in which it is found. The accreditation of a laboratory which undertakes calibrations ensures the long-term metrological traceability of national or international samples. The ultimate objective is the reduction of margins of error in making measurements.

Metrological confirmation

Calibration is a part of the management system of measurement instruments and it is a metrological confirmation for guaranteeing the conformity of equipment for measuring against the necessary requirements.

Broadly speaking, metrological confirmation includes:

The calibration

The calibration of instruments is carried out:

before their use;
when adjustments or repairs are done;
when required by a contract, before and after the final calibration.

The comparison

Errors revealed by means of calibration are compared with the metrological requirements for use of the measurement equipment.

The label

Finally the label is placed and then, where necessary, sealed.

The typologies

Calibrations are classified in relation with the metrological area to which the instruments, the systems and the measurement samples belong, in accordance with the quantities or properties against which they have been measured. The metrological areas include physical properties (mass, volume, force, length), physical properties such as pH, concentration of substance or areas including vehicles or ionized radiations.

Accredited calibration laboratories

Calibrations are performed by accredited calibration laboratories according to the ISO/IEC 17025.

DATABANKS