ASTM E74 certificate
The ASTM E74 standard is unique to the USA and serves the same purpose as the international standard ISO 376, i.e.: "Calibration of force measuring instruments used for the verification of uniaxial testing machines".
It deals more generally with the calibration methods which can be used to perform the calibration.
Categories of dynamometers
Two categories of force transducers are differentiated:
- class AA: for secondary force standard dynamometers, i.e. used as references for calibrating other dynamometers.
- class A: for dynamometers used for checking testing machines.
This distinction introduces differences in the calibration procedure.
The results of the calibration are used to define the area of use in the category to which the dynamometer belongs.
A key difference from ISO 376 is that the ASTM protocol is based in part on calibration uncertainty.