Instead of calibrations, opt for monitoring!
Connecting measurement equipment: when and how?

Legal Metrology invented calendar calibrations to guarantee fairness, and it obviously works very well. Today, no one disputes the results of measurements used in trade, whereas a little over two hundred years ago, our forefathers wanted "one weight and one measure" (without the cahiers de doléances, on the eve of the French Revolution).

In the industrial world, the relevance of this strategy is questionable. If it's useful to know an instrument's ability to compare with its reference unit, it's essential that it does so each time it's used. In fact, calibration only validates the past; it offers no guarantee for the "day-to-day". Unfortunately, no one can predict the inexorable date when it will no longer do its job properly, with potentially serious consequences if the problem goes undetected.

Quality standards therefore require the implementation...