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PROBLEM 1.1 FIND: Explain the hierarchy of standards. Explain the term standard. Cite example. SOLUTION
The term standard refers to an object or instrument, a method or a procedure that provides a value of an acceptable accuracy for comparison. A primary standard defines the value of the unit to which it is associated. Secondary standards, while based on the primary standard, are more readily accessible and amenable for use in a calibration. There is a hierarchy of secondary standards: A transfer standard might be maintained by a national standards lab (such as NIST in the United States) to calibrate industrial ¡°laboratory standards¡±. It is costly and time-consuming to certify a laboratory standard, so they are treated carefully and not used too regularly. A laboratory standard would be maintained by a company to be used to certify a more common in-house reference called the working standard. A working standard would be calibrated against the laboratory standard. The working standar¡¦(»ý·«)