pH Meter - Wide Range For Laboratory And Field Use

Frequently Asked Questions

Below are some of the more frequently asked questions our sales team often answer.

What Is PH?

pH stands for Potential Hydrogen.

Any substance’s pH level is defined by its acidity or alkalinity reading on the pH scale of 0 to 14. A reading of 7 is neutral, 0 pH is acidic, and 14 pH is alkaline. The pH level can affect many parameters in virtually all processes and production.

What is a pH Meter?

It is an analytical instrument used to measure hydrogen ions in a solution, and the readings are expressed as pH. Some pH meters can also measure other parameters, such as conductivity, Ion concentration, ORP and dissolved Oxygen when combined with the correct probe 

How does a pH Meter work?  

The purpose of a pH meter is to measure the voltage between two electrodes, the reference electrode and a pH electrode (glass electrode) and display the converted result as a pH value on a digital LCD screen. The output can be digital or analog, with the devices either battery or line powered.

Usually, there is a glass, a reference electrode, or a combination electrode. A silver chloride electrode or calomel electrode is typically required on each side of the membrane to measure the potential difference between the two sides of the glass membrane reference electrodes. 

How do I maintain my pH meter?

To prolong your meter’s life span and maintain its accuracy (after calibration), you need to follow some basic cleaning steps.

• Firstly, you must always wash the pH electrode in clean water after each use. Do not touch the electrode with your hands or fingers, but use a damp cloth with care.Never rub the electrode with a cloth and this will generate a voltage. 
• When you are not using the pH meter electrode, it must be kept moist. There are two options, a storage solution or a pH 4 solution.
• If you allow your sensor to dry out, it will become slow to take readings that could be inaccurate and invalidate your warranty.

Where are pH meters used?

pH meters are in use across a wide range of industries and sectors, including:

Water Analysis – Testing the water quality in swimming pools, wastewater, a spa, aquarium and drinking water.

Agriculture – Understanding soil, fertiliser, grains, fruit, and vegetables’ pH values is critical for the agricultural industry.

Chemical Industry – just about all manufactured chemicals will have a pH specification that must be checked. 

Health Care and Pharmaceutical – Testing blood chemistry, liquid syrups and drugs.

Cosmetics – The pH level is consistently measured during manufacturing to ensure consistency and quality.

Electroplating Industry – The pH level decides the plating quality, and knowing the pH level of pure water is critical in ensuring the pH of the electrolytic bath.

Food and Beverages – Knowing the pH value is vital in the food and beverage industry as it is one of the key factors in controlling the quality of wine, coffee, soft drinks, sauces, jams and dairy products.

How to calibrate your pH meter.

To calibrate your pH meter, you will require a pH buffer solution, a standard and inexpensive solution produced at a set pH level. If you plan to take several readings daily, you must calibrate your meter beforehand. However, a weekly calibration will be enough if you only intend to use it 2 -3 times per week.

For accurate calibration, you must use a minimum of  two different buffer solutions, spanning the pH values that require measuring and, for general purposes, buffer solutions at pH 4.00 and pH 10.00 are suitable. Some older pH meters only allow adjustment at a single point where modern pH meters allow adjustment at two or three points; this helps ensure linearity across the working range of the meter. 

How do you choose the right pH meter for your needs?

There are 5 key areas you may need to consider when choosing the right pH meter.

1. Accuracy – The more accurate the meter is, the more expensive it is. If you are conducting research or a quality assurance, then you may need one that is accurate to +/- 0.001 or 0.01. However, for an educational laboratory, a meter that is accurate to =/- 0.10, would suffice.
2. Calibration – Consider purchasing a meter that uses at least a 2-point calibration and calibrate as close to your expected result as possible (e.g. for acidified foods, you will calibrate your meter with pH 4.0 and 7.0 buffers). It is possible to buy 3-point and 5-point calibration pH meters which increases the accuracy of the measurement range, but it is unlikely you will need this unless you need to test a wide range of pH. Newer meters and testers also have much simpler single step calibration procedures, both on benches and pocket meters. 
3. Electrode – In some industries, such as food and beverage, there is a no glass policy. So, if you operate in that area, then you shouldn’t purchase a glass blub electrode. There are non-glass electrodes available, but they do cost more.
4. Temperature – Temperature has an effect on pH readings. Modern advanced meters will have an in-built temperature compensation feature. However, cheaper ones do not, meaning you will have to calibrate the meter at the same temperature as the testing sample.
5. Portability – Where are you going to use the meter? If you are in a laboratory, then you will need a benchtop meter, which has a higher accuracy with additional functions. If you need to use the meter in the field, then a hand-held portable meter will do.

Get In Contact With AML Instruments

Please contact us if you want more information or a quote about our products or services.

You can call us on Tel: 01522 789 375or email us at sales@amlinstruments.co.uk