Vaisala spot-checking and calibration eGuide

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Field spot-checking is a common way to determine the measurement accuracy of a fixed measurement instrument between calibration intervals. However, it is important to understand that spot-checking is different from field calibration. The Vaisala eGuide provides a brief outline on some of the differences.

Spot-checking and field calibration are similar in that they both use a reference standard to verify the measurement against the unit under test.

Spot-checking is a less time-consuming process than calibration, in part because the calibration process can include as-found data, adjustment (if necessary) and as-left data, whereas spot-checking is a verification that the unit under test is still within specification. It is helpful to remember that the calibration process deals with the instrument involved, not the measurements it produces. Field calibration processes should be performed under normal process conditions using standard laboratory determinations of sample concentration.

Like calibration, quality guidelines should have defined intervals for spot-checking. Guidelines should be defined beforehand with pre-established limits to determine potential actions based on results of the checks.

Spot-checking can also be part of a verification process because it is designed to ensure that measurement output on a process sensor is within specifications. Simply stated, in spot-checking, verification and field calibration, users are comparing measurements. Ideally, the device used to check is known to be accurate based on its calibration status. However, there are differences in spot-checking, verification and calibration, most importantly, in calibration users may make decisions and adjustments based on comparison.

Download the Vaisala eGuide for spot-checking and calibration.