pH Meters

A GAOTek pH Meter is an electric device that measures the acidity and alkalinity of a sample solution. The pH meter measures the difference between the reference electrode and the electrical potential between pH electrode. GAOTek high-performance conductivity meters are reliable, high quality, and inexpensive pieces of equipment that provide an accurate measuring for easier inspection or testing. It is user-friendly, easy to carry and portable to allow the user to work in complex conditions and are ideal for new users.


pH is an abbreviation of “pondus hydrogenii” and in 1909, it was proposed by a Danish scientist S.P.L. Sorensen to determine the concentrations of hydrogen ions. pH was based on the negative base 10 logarithms of the hydrogen ion concentration. 

pH is measured using a setup with two electrodes and its value range from 0-14. The indicator electrode and the reference electrode are the two electrodes used, which are often combined into one combined electrode. A small galvanic cell is developed when the two electrodes are mixed into a the solution.

The meter’s electrode is filled with an electrolyte solution that responds to the presence of positively charged Hydrogen ions. The electrolyte does this either by accepting or releasing electrons in an effort to keep the environment charge-neutral, with no more positively charged particles than negatively charged ones.

Ideal measuring conditions exist when only the potential of the indicator electrode changes in response to varying pH, while the potential of the reference electrode remains constant.

A pH meter consists of a voltmeter attached to a pH-responsive electrode and a variable reference electrode. The pH-responsive electrode is usually glass, and while the reference is usually a mercury chloride electrode, although it can be a silver chloride electrode. When the two electrodes are joined in a solution, they act as a battery. The glass electrode develops a charge that is directly related to the hydrogen-ion activity in the solution, and the voltmeter measures the potential difference between the glass and reference electrodes.

It is important to consider these factors when using the pH meter for more precise result and a longer life span:

·         The Accuracy is the most important factor when measuring pH. When using the pH meter, it is recommended to use an accuracy of at least ±0.02 units.

·         The Electrode is one of the part of the pH meter immersed in the sample. Select an electrode that is suitable to the sample it is testing.

·         The Ability to store test results, as well as cancelling, viewing and printing them. Can store sets of data

·         Optional 5 kinds of pH buffer solutions can make 1-3 points automatic calibration

·         Use a proper pH meter suitable to the application or environment it will be used for such as a bench top model for laboratory use or handheld model in plant applications.

·         Temperature can affect the pH reading. Normally, a pH meter is calibrated at room temperature but it is important to calibrate the pH meter into the same temperature as the environment in which the samples will be tested.

·         When calibrating a pH meter, it is recommended to calibrate it against a known standard to ascertain the accuracy each time it will be used.

·         Selecting a pH meter with at least a two-point calibration offers the most accurate results.


GAOTek pH meters are reliable, accurate, and easy to use to help prevent failure in operations. They also may have the following features:

·         Selectable pH buffer. It follows standard (USA/NIST/DIN) and it can offer custom calibration solutions

·         Auto hold function freezes the stable measured value for easier viewing and recording of data

·         Network function: RS232 bidirectional communication, equipped with a printer or TLab8.0 communications and data processing software

·         Can connect to PC via USB connection for networking, printing, weigh scale measurements and data transfer capabilities

·         System menu allows setting the 9 parameters, including the pH buffer standard, number of calibration points, resolution, stability condition, temperature unit, etc.

·         Automatic electrode slope display indicates when the users should consider replacing the sensor

·         Standard liquid temperature auto conversion: It pre-stores the temperature curve of the standard liquid; in the calibration, it can convert pH value of the standard liquid automatically at the set temperature

·         It is computer based and adopts high-performance CPU chip, high precision AD conversion technology and SMT technology to complete the multi-parameter measurement, instrument self-checking, and temperature compensation, thus giving high precision results and good repeatability

·         Multi-mode power scheme (battery, power adapter, computer’s USB port)


pH meters are employed in many applications like chemical industry, Hexavalent chromium destruction, water purification processes which uses reverse osmosis, electroplating, cyanide destruction, neutralization of effluent in steel, pulp and paper, petrochemical industries, pharmaceutical manufacturing and biotechnology etc. The pH meter helps in analyzing the exact pH value of chemical substances and food products, thus ensures the safety and quality in the applications it is employed to.

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