Calibration

Calibration (following the English word " calibration" and calibration) in metrology is a measurement process for reliably reproducible detection and documentation of the deviation of a measuring instrument or a measuring scale to another device or other material measure, referred to in this case as normal. In the definition of the VIM of JCGM 2008 absolutely is added a second step in defining the calibration, namely the consideration of the determined deviation in the subsequent use of the instrument to the correction of the readings.

The term calibration is often confused with the nonsynonymous words calibration, conformity statement, specification testing, adjustment, calibration or certification, to delimit see below.

Traceability

With a traceable calibration first a traceable standard is employed. Such a normal itself has a calibration that through an unbroken chain of calibrations has a relationship to the definitions of the SI units. This relationship is expressed by the two parameter deviation and calibration uncertainty. If the calibration results are now again expressed with variation and uncertainty, including this calibration result is traceable. Traceability is thus the property of a result and not a device.

Increase of the uncertainty in calibration

With every calibration along the traceability chain uncertainty rises. The calibrated items are thus always lower order (of lower order ) than the normal with which they were calibrated.

Calibration is a snapshot

Calibration is a snapshot. Statements about the temporal behavior (drift, shift engl. ) Of a measuring instrument can be made only after several calibrations were performed. Only through these considerations and appropriate additional uncertainty contributions keep measuring results even for the duration between two calibration intervals, traceability.

Procedure for calibration

Belongs to a calibration

• The definition of the measurement process, environmental conditions
• Required standards
• Method

Accreditation

National accreditation bodies accredit calibration laboratories and thereby confirm their competence carried out in the scope of accreditation calibrations.

Differentiation from other concepts

• Calibration is the confirmation of the conformity of the law after custody meter with a national legal provision.
• A statement of conformity or specification test can be performed on a calibration in the port, but is not a mandatory component.
• An adjustment or adjustment can be made following a calibration and conformance testing (eg, if the discrepancy is too high ), but is not a mandatory component. After each adjustment, a new calibration must take place because of the change to the meter a previously performed calibration is meaningless. The first calibration is referred to as the ' as found ', the second as ' as left '.
• A certification is a confirmation of an independent certification body that one thing (product, person, system ) meets all the requirements of a request list.

Example

An illustrative example is the calibration of a self-registering scale by hanging of weights than normal. Taking into account systematic influences ( previously determined by calibration measurement deviations of the weights, air pressure, temperature, buoyancy forces) and random influences the display of the balance is compared to the mass launched and estimated the uncertainty of this deviation. A simple calibration result is: The balance display has a load of 200 g, a deviation of 0.12 g; This result has an uncertainty of 0.20 g with a confidence interval of 95%.

Directives and Standards

DIN EN ISO 9001:2008: In this set of rules for the certification of quality management systems, it is required that for the manufactured product quality-related characteristics with calibrated measuring instruments are measured.

In addition to the requirements and technical measures of quality assurance and quality management, such as test equipment and traceable calibration of measuring equipment includes the Calibration Guideline 2622 of VDI, VDE, DGQ and DKD ( German Calibration Service) general directions for calibration models for the measurement uncertainty and traceability of measuring sizes for most electric and electronic instruments.

Calibration is out of the measurement technique

• In financial mathematics, the process of fitting a model to prices of derivatives is called calibrating.

• In statistics, refers to the reversal of a regression as a calibration.

In connection with the radiocarbon dating is denoted by calibration or calibration the calibration of the measured radiocarbon age of a sample with independent scales (eg, dendrochronology ), so the age of the sample in solar years can be converted.