ASTM E 74 Standard Standards ISO 376 ISO 7500 EN 12390 ASTM E 74

This standard elaborated in the US has the same purpose as international Standard ISO 376.
It deals more generally with calibration methods.
It establishes two separate categories of force standard reference force transducers:

  1. Class AA, meant for secondary standard reference force dynamometers, i.e., used as reference for the calibration of other dynamometers.
  2. Class A, for dynamometers used for verification of testing machines.

This distinction introduces differences in the calibration procedure.
The results of calibration serve the purpose of defining the scope of application within the category the dynamometer belongs to.
An essential difference with ISO 376 Standard derives from the fact that the ASTM protocol is partly based on calibration inaccuracy.