When is substitution of standards permissible?

Substitution of standards is permissible when it is technically feasible and not forbidden by procedure. This principle is crucial in calibration practices, as it allows flexibility in the use of measurement standards while adhering to established protocols that ensure accuracy and reliability.

When a standard is substituted, it's essential that the substitute can fulfill the same requirements as the original. This means it should possess the same or better accuracy, stability, and reliability, thereby maintaining the integrity of the measurement system. Additionally, the procedure or guidelines governing the calibration process must explicitly allow for such substitutions; this ensures that all practices remain compliant with industry standards and regulations.

The financial feasibility or potential improvements in accuracy are not sufficient alone to justify a substitution if the procedure doesn’t allow it. Thus, while considering cost or aiming for better precision is important, adherence to technical feasibility and procedural guidelines takes precedence in making such decisions.