What is Metrology?
The term ‘metrology’ is derived from the Greek word ‘metron’, which means ‘to measure’. In essence, metrology is the science of measurement.
Metrology deals with:
- Measurement theory
- Units of measurement and their physical realization
- Measurement processes, procedures and methods
- Characteristics of measuring instruments.
Categories of metrology
Metrology is separated into three categories with different levels of complexity and accuracy:
- Scientific metrology, which deals with the organization and development of measurement standards and with their maintenance
- Industrial metrology, which has to ensure the adequate functioning of measurement instruments used in industry, as well as in production and testing processes
- Legal metrology, which is primarily concerned with the accuracy of measurements where these have influence on the transparency of economic transactions.
Fundamental metrology has no international definition, but it signifies the highest level of accuracy within a given field. Fundamental metrology may therefore be described as scientific metrology, supplemented by those parts of legal and industrial metrology that require scientific competence.
A traceability chain is an unbroken chain of comparisons which make certain that a measurement result, or value, is related to references at a higher level, ending at the final level with a primary standard.
Instrument calibration is a basic tool designed to ensure the traceability of a measurement. It involves determining the metrological characteristics of an instrument and is achieved by means of a direct comparison against standards.
There are three main reasons for having instruments calibrated:
- To ensure readings from an instrument are consistent with other measurements
- To determine the accuracy of the instrument readings
- To establish the reliability of the instrument.
A measurement standard or "etalon" can be either:
- A material measure
- A measuring instrument
- A reference material
- A measuring system.
The purpose of a measurement standard is to define, realize, conserve or reproduce a unit or one or more values of a quantity to serve as a reference.
Metrology in the Economy
Metrology plays an important role in many areas of the economy.
Consumer protection and fair trading are the underlying principles for the operation of the Legal Metrology Service. Every trader and citizen expects equity and fairness in the market place. The use of a uniform system of units of measurement and trust in measuring instruments and systems are necessities to ensure that both are achieved.
Quality and efficiency for many aspects of industrial processes and operations depend on the metrological integrity of instruments or systems. Compliance with quality system certification often requires test and inspection equipment to have international traceability.
Diminishing trade barriers result as the confidence in traceability of measurement results is enhanced. Much legislation or de facto regulatory requirements exist for many products due to specifications or requirements established by different legal authorities or industries. With the use of a uniform system of measurement units and traceability of results to common internationally accepted standards, the exchange of test results and certificates is enabled, thus reducing the burden on business operators.
For more information
For more information about legal metrology in Ireland, go to About the NSAI Legal Metrology.
For more information about industrial metrology go to the NSAI National Metrology Laboratory.
For more information on measurement units and the metric system go to About the Metric System.