How to Use a pH Meter to Test Water?
Water can be acidic, neutral, or alkaline depending upon the pH level or the hydrogen ion concentration in it. The level of pH needs to be tested for certain applications ranging from potable water to water used in industrial units. pH meters are used for this purpose, and there are several brands available in the market. There are certain steps to follow and factors to consider when using a pH meter for water testing. This post talks about the factors you should consider when buying pH meters and how to use them to get accurate results.
What Are the Different Factors to Consider When Buying a pH Meter?
Monitoring of pH is important because it impacts the chemical properties of water such as solubility, acidic nature, and so on. All these factors affect its suitability for use or consumption. Also, certain organisms thrive in water at a certain pH. Here are some factors which may help when buying a pH meter:
- A typical pH meter is made of two components – a digital or moving coil pH meter, and two probes. Some pH meters may have one probe, too. If your device has two probes, perhaps both of them act as different electrodes. The probe in a single probe device is made of two different electrodes, and integrated for the purpose of simplicity. Both the pH meter and electrode must be durable as they need to withstand the contaminants, chemicals, particles, and so on in a water sample depending upon the application.
- Electrodes can be easily damaged by contaminants and chemicals, and hence a double junction electrode is always recommended. These are especially useful for applications which involve solid particles, chemicals, or sludge such as wastewater and pulp & paper.
- Both highly alkaline and highly acidic water impact its usage. For instance, highly alkaline water many not only taste bitter but also leave deposits on utensils, pipes, and so on. On the other hand, highly acidic water may react or dissolve metals and corrode the surfaces or pipes and utensils. So, the ideal pH range should be 6–8.
- Consider a 2-point calibration for acidic and basic level measurements. The former could be adjusted from 4 to 7, and the latter from 7 to 10.
- Check the number of parameters featured in the pH measurement probe. Make sure there are at least six to ten parameters of measurement depending on the application requirement.
- Check factors such as flexibility and portability, and the level of technology used. There are pH meters, which can function without much manual intervention.
- If you deal with dirty water, you can use a flushable junction, as they can be easily cleaned off wastewater particles, sludge, paper pulp, or any other waste.
Steps for Using a pH Meter
You would primarily require a testing kit to test a water sample. It comprises a pH meter, probe, stirrer, pH electrode, a calibrated cylinder, a jar or beaker, sample of deionized water, and buffers. Here are steps to test the water sample using a pH meter:
- The logarithmic scale of a pH meter is set from 1–14, wherein 1–6 is acidic, 7 is neutral, and 8–14 is alkaline.
- Take a calibrated beaker and pour 100 ml water to be tested for pH as that is the standard sampling quantity.
- Switch on your pH meter and allow it to warm up for about half an hour.
- Reduce the exposure to air as much as possible, because the water, in case it is alkaline, may react with atmospheric carbon dioxide to form carbonic acid.
- Use distilled water to store the pH probe before it is used for testing.
- Rinse the probe and set the pH mode, and place it in a neutral buffer solution (with pH 7) for calibration. Similarly, place it in a buffer solution with pH 4. This allows the meter to calibrate for acidic solutions. In case of basic solutions, place the probe in a buffer solution with pH 9 after placing it in a neutral buffer.
- It is a good practice to stir all the buffer solutions well before use.
- Shake off any excess fluid on the device before you place it in the sample liquid or water.
- Place the device in the sample and press the measure pH button. You should get a stable reading in about two minutes.
- Get another reading for accuracy. Match the pH meter’s value with that of the buffer.
- Place the electrode in the correct buffer solution and press measure to take the reading.
- Rinse and dry the electrode well
- Now, place the electrode in the sample, press the measure button, and keep it for about two minutes.
- This is your pH reading.
- Clean the electrode after use.
If you are looking for pH meters even for the simplest of applications, ensure you source them from reliable suppliers. Cannon Water Technology is one of the well-known distributors of chemical pumps, pH meters, and various test and filtration equipment. The company stocks pH meters from industry-leading brands like Myron L and Hanna Instruments.