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The next quality standard in the hierarchy is known as a secondary standard. Secondary standards are calibrated with reference to a primary standard. [2] The third level of standard, a standard which is periodically calibrated against a secondary standard, is known as a working standard. [2] Working standards are used for the calibration of ...
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.
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 ...
Secondary reference standards: Reference standards calibrated against and traceable to primary WHO materials and intended for use in routine tests; Reference reagent: a WHO reference standard, the activity of which is defined by WHO in terms of a unit; For chemical substances some pharmacopoeias [10] use the WHO terms [11]
Secondary instruments must be calibrated against a primary standard. For example: a dial bourdon tube type pressure gauge must be calibrated against a water or mercury U tube to assure good accuracy. Time. The earth moving in its orbit is primary. Clocks must be calibrated against it.
A standard solution created from a secondary standard cannot have its concentration accurately known without stoichiometric analysis against a primary standard. An example of a secondary standard is sodium hydroxide, a hydroscopic compound that is highly reactive with its surroundings. The concentration of a standard solution made with sodium ...
Secondary education or post-primary education covers two phases on the International Standard Classification of Education scale. Level 2 or lower secondary education (less commonly junior secondary education ) is considered the second and final phase of basic education , and level 3 upper secondary education or senior secondary education is the ...
European Standard (EN 13402-1) pictogram example for a men's jacket, with chest as primary measurement, and height and waist as secondary measurements. The first part [2] of the standard defines the list of body dimensions to be used for designating clothing sizes, together with an anatomical explanations and measurement guidelines. All body ...