What does the ASTM E74 standard specifically say about calibration class load cells?
• It outlines a procedure on how load cells should be calibrated and the terminology used. • Load cells should be tested by deadweight testing machines and hydraulic test machines and specifies the uncertainty of these weights and how local gravity needs to be determined. • It defines how the linearity curve should be defined as a polynomial curve with a 2nd order fit but that up to 5th order can be used. • It states that a calibration should be carried out at 10%, 20%, 30%, 40% 50%, 60%, 70%, 80%, 90%, 100% in ascending loading only. It also states that if increments in deadweights cannot be obtained to carry out these percentages that alternatives can be used but need to be specified in the calibration certificate. • A calibrated load cell cannot be used below 10% unless weights were applied below 10% and calibration results obtained. • A load cell can never be used below 2000 times the uncertainty of the cell for a class AA load cell and 400x the uncertainty. • A load cell should ne
