pH Testers: How to Read Specifications

A pH tester is a device used to measure the acidity or alkalinity of a solution.

There is an extensive range of pH testers available at Instrument Choice, each with different specifications. So, to help you select the best pH tester for your application, we have put together a glossary of key terms and definitions you are bound to encounter in pH tester specifications.

Electrode

The electrode is the sensor used to measure the pH value of a substance.

Measurement Range

Specifications will define and display a pH tester’s measurement range capability as the minimum and maximum values.

Resolution

Refers to the smallest possible value that your pH tester can display. For example, a pH tester with a resolution of 0.01pH will read to the nearest 0.01.

Accuracy

Accuracy is the closeness of a measurement to a specific value. Specifications will express the accuracy of a device as a range, plus or minus a set amount—for example, ±0.1pH.

Automatic Temperature Compensation

The temperature of a sample has a substantial effect on the accuracy of pH readings. With automatic temperature compensation (ATC), your device will automatically account for the sample temperature when taking pH measurements and correct the displayed pH value accordingly, resulting in the most accurate measurement possible.

Calibration

Device specifications will outline whether or not a pH tester can be user-calibrated, and if so, to how many calibration points. Calibration is essential to ensure accuracy.

Minimum Sample Volume

Refers to the smallest sample volume required for a pH tester to perform an accurate pH measurement.

Sampling Rate

The sample rate or time is how long it will take the pH tester to measure pH and obtain a stable result.

Single and Double Junction

When selecting a pH tester, the junction is a significant physical characteristic of the electrode you must consider. There are two main types:

1. Single junction: Single junction electrodes put the reference electrode system in contact with the sample to be measured. These are the most economical and work well in general purpose applications.
2. Double junction: Double junction electrodes isolate the reference electrode, minimising the risk of contamination to the reference electrode. Double junction electrodes should be used on samples that contain sulphides or heavy metals to prevent contamination of the reference cell.

Operating Conditions/Temperature:

For accurate measurements, pH tester specifications will detail a device’s operating temperature range. The operating range will display as a minimum and maximum temperature, sometimes with the addition of a humidity value, expressed as a percentage.

Conclusion

When searching for a pH tester, it is essential to understand pH tester specifications to select the best product for your needs and budget.

or want more terms and definitions? Contact an Instrument Choice Scientist: Call 1300 737 871 or email [email protected].

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• Frequently Asked Questions: pH Testers