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A primary standard in metrology is a standard that is sufficiently accurate such that it is not calibrated by or subordinate to other standards. Primary standards are defined via other quantities like length, mass and time. Primary standards are used to calibrate other standards referred to as working standards. [1] [2] See Hierarchy of Standards.
An example of a primary standard was the international prototype of the kilogram (IPK) which was the master kilogram and the primary mass standard for the International System of Units (SI). The IPK is a one kilogram mass of a platinum-iridium alloy maintained by the International Bureau of Weights and Measures (BIPM) in Sèvres, France.
There are three levels of standards in the hierarchy of metrology: primary, secondary, and working standards. [20] Primary standards (the highest quality) do not reference any other standards. Secondary standards are calibrated with reference to a primary standard. Working standards, used to calibrate (or check) measuring instruments or other ...
Examples of primary time, (i.e., frequency standards) are caesium standards and hydrogen masers. The international second is based on the microwave frequency (9,192,631,770 Hz) associated with the atomic resonance of the hyperfine ground state levels of the caesium-133 atom in a magnetically neutral environment.
The primary types of technical standards are: A standard specification is an explicit set of requirements for an item, material, component, system or service. It is often used to formalize the technical aspects of a procurement agreement or contract. [2]
These standards are conventionally accepted as best practice and used globally by industry and organizations. In circumstances and situations there are certain methods and systems that are used as benchmarks, guidelines or protocols for communication , measurement , orientation , reference for information , science , symbols and time .
These characteristics make primary standards reliable for preparing standard solutions with an accurate concentration just by knowing the amount of compound and solvent used. Primary standard solutions are commonly used to determine the concentration of secondary standard solutions through titration .
The formal definition of calibration by the International Bureau of Weights and Measures (BIPM) is the following: "Operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties (of the calibrated instrument or ...