Calibration and Maintenance Frequencies


• May be determined for individual instruments or groups of instruments (similarity of construction, reliability, and stability)

• Considerations when determining calibration frequency:

–Accuracy of the measurement / instrument range
–Consequences of incorrect value caused by out of calibration
–Extent & criticality of use of the instrument & tendency to wear and drift
–The manufacturer’s recommendations
–Environmental & physical conditions (temperature, humidity, vibration)
–Previous calibration records, history of calibration problems & repair history
–Frequency of calibration checks prior to use or in-between intervals
–Redundant / back-up systems (provides secondary source of information available from other calibrated primary instruments)
–Results of Qualification studies
–Process requirements
–Availability of built-in / automatic calibration checks

• Changes to frequency must be approved per change control SOPs

• References to specific instrument procedures listed in compendia (USP, BP or EP) for calibration tests for specific laboratory instruments

• Calibration time “windows” should be established around calibration due dates

• Policy for Calibration and Maintenance Intervals & Schedules Include:

⇒Extending Intervals
⇒Reducing Intervals
⇒Maximum Intervals