When will a radiac instrument require calibration prior to use?

A radiac instrument requires calibration prior to use if it has not been calibrated within the specified time frame set by the manufacturer or relevant regulations. Additionally, it should be recalibrated if it has been subjected to physical damage, significant temperature fluctuations, or if it shows inconsistent readings during testing. Calibration is also necessary after any maintenance or repair work that could affect its performance. Regular checks and calibration ensure accurate and reliable measurements.