How do you calibrate a pH meter?

How do you calibrate a pH meter?The fluids in the electrode of a pH meter age the longer the meter is being used. This causes measuring error in the instrument. You can determine this measuring error by calibrating your pH meter. This compares your result to the (inter)national determined standard value. How does calibrating the pH meter actually work?

How often should you calibrate?

How often you should calibrate your pH meter depends on usage and possible contamination. The higher these numbers, the more often you need to calibrate your meter. Stick with a minimum of twice monthly. It is also advisable to calibrate under the following circumstances:
  • When you use a new electrode
  • Whe the electrode hasn’t been used for a long time.
  • After the electrode has been cleaned.
  • After measuring a strong solution
  • When it is really important to get a very accurate measurement.

Preparation

Soak an electrode newly taken from the package or an electrode that has been dry for a long time in a beaker with additive fluid. Soak a regularly used electrode in a beaker with tap water for 15 minutes.

Calibrating the pH meter

To calibrate the pH meter you will need two types of buffer solutions: pH7 and pH4. Use fresh buffer solution for each calibration. 
  • First place the electrode in the pH7 solution. After approximately 1 minute the measurement will be stable. The meter should indicate a Ph value of 7.0. If this is not the case, then establish the pH meter at this value. 
  • Rinse the electrode well with demineralized water and then place the electrode in the pH4 buffer solution. 
  • Repeat these steps until a reliable measurement is obtained. The pH meter will then indicate a value by measuring the pH4 solution. The further this value is from the pH4 value, the greater the discrepancy of your measuring instrument.

In this video our product specialist shows you how to calibrate a pH meter:

Tip: put the subtitles on.

Difference between calibrating and gauging

The terms calibrating and gauging are often used interchangeably, but are not the same. When calibrating you determine how far your pH meter deviates from the standard. You do this yourself and there are no real consequences to this: you only determine the accuracy of your measuring instrument. Gauging is official verification where a specialist determines how the pH meter meets legal regulations. There are consequences to this: when a pH meter is rejected, it may no longer be used.

Nanne Bentvelzen
Questions regarding pH meter calibration

Questions regarding pH meter calibration, or would you like tailor-made advice? Contact product specialist Nanne Bentvelzen, or fill in the form below. On workingdays we will contact you within 24 hours. 


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