According to TNI 01 0115 (International Vocabulary of Metrology) calibration is an activity which, under the conditions specified in the first step, determines the relation between the values of variables with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to determine the relationship to obtain a result measurement of indications. Calibration certificate is issued and (in most cases) calibrated instrument is provided with calibration sticker or verification sticker.
Verification is a set of activities, which confirms that the legal measuring instrument has the required metrological characteristics. This requirement shall be considered satisfied if the gauge is in accordance with the requirement under the general measure. Procedure for verification of measuring instruments is provided by Ministry of Transport and Industry. Verified legal instrument is affixed by Czech Metrology Institute or an authorized metrological center with an official mark or issue a certificate of verification, or using both methods. Graphic appearance of the official mark and particulars of the certificate of verification are set by the Ministry of Transport and Industry decree.
The difference between calibration and verification
The calibration and verification is based on a practically related procedures. The difference is that while verification is investigation that metrological characteristics of these instruments are in compliance with officially established requirements, particularly with the maximum permissible errors, the calibration quantitatively determines the relationship between the measured value and the nominal value set by etalon benchmark. Both activities are a form of metrological traceability of measuring instruments.
Gauge, measuring instruments
Gauges are used to determine the measured value. Along with the necessary ancillary measuring devices for these purposes are divided into: standards, working gauges approved (or legal measuring instruments), working measuring instruments (or working gauges) and certified reference materials.
Standar of measuring unit or scale of certain quantity is a gauge used for the implementation and maintenance of this unit or scale and its transfer to the lower gauge accuracy. Maintenance of a standard means all the tasks required to maintain metrological characteristics of the standard within the prescribed limits.
Approved working gauges: Approved measuring instruments are measuring instruments which MIT decree for mandatory verification with regard to their relevance.
a) in contractual relationships, such as sale, lease or donation of a thing, the provision of services, or in determining the amount of damages, or, if necessary, other property damage
b) for determining penalties, fees, tariffs, taxes
c) to protect health of human
d) for Environmental protection
e) for safety at work
f) for protection of other public interests protected by special regulations
Working measuring instruments (or working gauges): Working measuring instruments are measuring instruments which are neither standards nor legal measuring instruments.
In the case of doubts classification of instrument into one of these categories is determined by Czech office for standards, metrology and testing (ÚNMZ).
Certified reference materials and other reference materials: are materials or substances of precisely determined composition or properties used primarily for verification or calibration of instruments, evaluation of measuring methods and quantitative determination of material properties.
Measurement uncertainty is a parameter associated with the result of a measurement that characterizes the dispersion of values that can be assigned to the measurand.It is a quantitative measure of the quality of the measurement results, allowing to compare the measurement results with other results, references, specifications or standards. Measurement uncertainty can be determined in different ways. Widely used and accepted method, eg accepted by the accreditation bodies is the recommended procedure "GUM", described as in the Guide to the Expression of Uncertainty Measurement.
Traceability is a property of a measurement result or value of the standard, which is intended by relation to national or international standards through an unbroken chain of comparisons with the corresponding uncertainties. Basically it is a classification of the instrument in an uninterrupted sequence of transfer of values variables beginning with the standard of the highest metrological quality. Traceability chain is unbroken chain of comparisons all having stated uncertainties. This ensures that the measurement result or the value of a standard is related to references at the higher levels, ending at the primary standards. End user may obtain traceability to the highest international level either directly from a National Metrology Institute or through secondary calibration laboratory, usually accredited. As a result of various international agreements on mutual recognition is the fact that traceablitiy can be ensured through laboratories outside the user's own country.
Full legislation, including amendments and regulations in the field of metrology on the website of Czech office for standards, metrology and testing (ÚNMZ).