Calibration frequency of Instrumentation is generally dictated by contract or regulation requirements. Additional guidelines can be offered by the manufacturer if needed.

For Instruments that are not installed in fixed positions i.e. portable, or are not required for continuous monitoring, the manufacturer would advise that where possible annual calibration is recommended. Regular calibration of portable instrumentation is essential as the instruments are more exposed to various influences.

Manufacturer guidelines are intended to be guidelines only, many factors might influence the calibration frequency decision. Some of these factors might be usage, system performance indicators and environmental effects. The users should conclude the calibration requirement based on all factors presented.

Instrumentation that is installed for long term monitoring of structures should be calibrated pre installation. Following installation further calibration periods should be decided based on monitoring requirements and system performance. Commonly due to instrumentation being installed in an environment where it remains untouched calibration periods might be further apart.

Typically instruments are not recalibrated during long term monitoring of a structure unless results have raised concern and there is call for the instruments to be verified.