The more the fluids in the electrode of a pH meterage, the longer the meter is in use. This creates a measurement error in the pH meter. You can determine this measurement error by calibrating your pH meter. You compare the result of the measurement with the (inter-) nationally determined standard value. But how is a pH meter calibrated at all?
How to calibrate pH meters?
How to calibrate pH meters in four steps:
- To calibrate your pH meter, you need two types of buffer fluid: pH7 and pH4. Use fresh buffer fluid for each calibration.
- First, place the electrode in the pH7 buffer fluid. After about a minute, measuring your pH meter is stable. The pH meter must then display a pH of 7.0. If this is not the case, set the pH meter to this value.
- Rinse the electrode thoroughly with demineralized water and place the wire in the pH4 buffer liquid.
- Repeat these steps until a reliable measurement is obtained in both fluids. The pH meter then displays a value in the pH4 buffer liquid measurement. The farther this value is from the pH4 value, the higher the deviation of the meter.
What factors can cause a wrong reading of a pH meter?
In general, three factors can generate a wrong reading of the pH of the water:
1.- Failure to calibrate the meter.
2.- Dirt in the pH probe.
3.- Low battery level.
How often do pH meters calibrate?
The number of times you need to calibrate your pH meter depends on how it is used and how dirty it is. The higher these values are, the more often you need to calibrate the pH meter. Do this at least two times a month. It is also recommended to calibrate your pH meter in the following cases:
- If you use a new electrode.
- If the electrode has not been used for a long time.
- After the electrode has been cleaned.
- After measuring in a reliable solution.
- When a very accurate measurement is required.
An electrode that has just been removed from the package or a wire that has been left dry for a long time must first be placed in a cup of storage fluid for at least four hours. An electrode that is used regularly should first be placed in a beaker of tap water for a quarter of an hour.
What happens if the meter does not show the correct reading when it reaches the top of the turn?
This can happen for two reasons:
1.- The probe is dirty and gives an erroneous reading.
2.- The pH probe of the meter has reached the end of its useful life.
In the first case, we should get the cleaning fluid for the probe, and immerse it in it for 24 hours, the period after which we will try to calibrate it again.
In the second case, there will be no solution other than buying a new pH probe (in fact, the probe is replaceable) or a new pH meter.
How can I extend the life of my pH meter?
The pH probes of the meters are quite fragile, so it is advisable to treat them as best as possible, especially if our meter has spent long periods without being used.
On the one hand, it is advisable to keep the pH probe clean, so from here, we advise our readers that after each use, they clean it with osmosis or distilled water, this can prevent accumulations of salts in the probe that deteriorate it prematurely.
On the other hand, if we know that we will not use our meter in a while, it is advisable to use the storage solution. We only have to fill the cap of our meter with this solution and leave it in a vertical position during its storage.
Difference between calibrating and calibrating a pH meter
The terms “calibrate” and “oak” are often used interchangeably but are not the same. During calibration, you determine how far the pH meter deviates from the norm. You will do it yourself, and there are no consequences: you only learn the accuracy of your pH meter. Oaks is an official test in which a specialist determines to what extent the pH meter meets the legal requirements. There are consequences to this: if the pH meter fails the test, it must no longer be used.