Test Meter Calibration
Calibrating test meters is important in ensuring the accuracy of recorded values and the repeatability of results. Test meters can lose calibration gradually over time and with repeated use, which makes it necessary to calibrate frequently. Calibration is accomplished by comparing recorded values with a known standard and making corrections to the instrument if a discrepancy exists. Test meter calibration is generally straightforward for most meter types and takes only a few moments each day.
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Instructions
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Obtain a known standard. Standards are available for a variety of test meters including light and conductivity meters. For some meters there will be a single standard, while calibrating others may require more. For example, pH meter calibration requires at least two and sometimes three standard solutions each at a known pH (e.g. four, seven and 10).
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Turn the meter to calibration mode if the meter has one. Measure the standard solution with the meter you are calibrating. You may have to enter the value of the standard into the meter.
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Wait for the meter to stop drifting and reach equilibrium.
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Push the enter button, or whichever button records your meter's measurements. If the test meter does not have a calibration function, you may have to record the discrepancy between the known value of the standard and the measured value and make the correction as you are taking measurements. For example, if a standard buffer solution has a pH of four and the meter reads 3.9, simply add 0.1 to each recorded measurement.
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Switch the meter back into measurement mode, if you need to, before taking readings with the test meter.
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Tips & Warnings
Every test meter will come with a set of calibration instructions you can follow if you need to troubleshoot.
Resources
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