Re-calibration

For a quick recap, I recently talked about calibration and its importance, but we missed one last crucial aspect of the entire calibration process, Re-Calibration. Many companies purchasing calibratable technology always ask the following question: “What is your recalibration process?”. Here I will explain what the re-calibration process should be when deciding which vendors to choose for re-calibration purposes.

Re-Calibration Process

Before sensors/probes are purchased by customers calibration assessments should be performed for accuracy, tolerance, criticality of the instrument, and calibrated range. This allows customers to set their parameters ahead of time for calibrated probes and sensors to be purchased which sets the groundwork for re-calibration acceptance criteria. When re-calibrating, calibration labs will do a “as found” and a “as left” readings, which is a reading before adjusting any parameters within the probe/sensor (as found), then a reading if an adjustment of parameters within the probe sensor is performed (as left). The probe/sensor needs to be verified that it was within calibration during the period in use (as found). This is considered a performance verification and if some parameters of the probe/sensor are out of calibration acceptance criteria then the customer needs to be notified of the deviation or discrepancy. The customer can then assess any work that was completed with the sensor/probe.

When should Re-calibration occur?

Great question!  The time between calibration and re-calibration depends on the industry you are in, the standards practiced in that industry, the criticality of the instrument (assessment), and the type of sensors you have within your facility.  In the pharmaceutical industry standard practice if 6 months or 12 months depending on criticality and the calibration assessment performed before sensor/probe purchase.  More critical instruments require a 6- month calibration, while less critical instruments can get by with a 12-month (1 year) re-calibration.  If you are using less stable probes and sensors it would be wise to have calibration occur more frequently.

The Decision

The decision to re-calibrate is solely on the customer but calibration vendors can help decide what is the best course of action for certain probes and sensors. Just make sure the calibration vendor is ISO 17025 accredited and can provide re-calibration services to your specifications!