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ORP Meter

ORP meter used in laboratory

1. What is ORP meter?
    1.1 What is OPR?
        1.1.1 ORP measurement
    1.2 Performance features of ORP meter
    1.3 Machine parameters of ORP meter
2. Type of ORP meter
3. Use of ORP meter
    3.1 Precautions of ORP meter
4. How to buy ORP meter?

What is ORP meter?

ORP meter, also known as oxidation-reduction potential meter, is an instrument designed to reflect the macroscopic oxidation-reduction properties exhibited by all substances in an aqueous solution.

Redox meter is a special instrument for testing the redox potential of solutions, which consists of a composite electrode and an mv meter. The composite electrode is a kind of electrode that can absorb or release electrons on the surface of its sensitive layer, which is an inert metal, usually made of platinum and gold. The silver/silver chloride electrode is used as the reference electrode and is the same as the pH electrode. The millivoltmeter is also the secondary meter and the pH meter can be common.

A positive potential means that the solution shows some oxidation, while a negative potential means that the solution shows reduction. BRP-200 redox potentiometer is specially designed to detect the oxidation and reduction ability of water.

ORP meter can be equipped with three composite or two composite electrodes to meet a variety of useful sites. It can be widely used for continuous monitoring of ORP of various water quality in electric power, chemical, environmental protection, pharmaceutical, and food industries.

What is OPR?

ORP is the abbreviation of Oxidation-Reduction Potential, which indicates the redox potential of a solution. ORP value (redox potential) is an important indicator of water quality, it cannot independently respond to good or bad water quality, but can be integrated with other water quality indicators to respond to the ecological environment in the aquarium system. In the water, each material has its own redox characteristics. Simply, we can understand that: at the microscopic level, each different substance has a certain oxidation-reduction ability, these redox different substances can interact with each other, and ultimately constitute a certain macroscopic redox property. The so-called redox potential is used to respond to the macroscopic oxidation-reduction properties of all the substances reacting out of the aqueous solution. The higher the redox potential, the stronger the oxidation, and the lower the potential, the weaker the oxidation. Solutions that show some oxidations are positive potential, while solutions that show reduction are negative potential.

The function of a pH electrode is to convert the activity of hydrogen ions in solution into electric potential, and the function of a pH meter is to measure the electric potential generated by the pH electrode, convert it into pH value and display it
ORP meter is a new redox potential analyzer, while a pH meter measures the pH value of the solution with the instrument.

Oxidation and reduction always occur together, oxidation comes from the transfer of charge between atoms in any chemical reaction, atoms that lose electrons are oxidized and those that gain electrons are reduced. Chemicals such as chlorine, sodium hypochlorite, bromine, and ozone are all strong oxidizers and their ability to oxidize or gain electrons from other substances is what makes them great disinfectants, the disinfection is attributed to their chemical composition that can alter harmful organisms. Oxidizers literally burn off bacteria, germs, and other organic matter from the water, leaving behind some harmless chemicals as a by-product. As the ORP measurement increases, the solution has a greater oxidizing potential, thus destroying any organisms and doing so more quickly.

ORP measurement

ORP measuring electrodes are the same as pH measuring electrodes, but use precious metals instead of glass electrodes as the measuring element. Inert metals are used because they do not participate in chemical reactions, most commonly, the measuring electrode is made of platinum, but other highly precious metals such as gold or silver can also be used. When the indicator electrode is immersed in water containing oxidizing and reducing agents, the ORP sensor produces a very small voltage, which is measured between the indicator electrode (positive platinum electrode) and the reference electrode (negative electrode), with water in between. The measuring electrode (+) of the probe is usually made of platinum and the reference electrode (-) is usually made of silver, surrounded by an electrolyte solution. The voltage difference between the two electrodes is actually the output of the ORP sensor. An oxidizer is added to the water and it gains electrons from the surface of the platinum-measuring electrode, causing the electrode to become increasingly positively charged. As you continue to add the oxidizer to the water, the electrode produces a higher and higher positive voltage.

Performance features of ORP meter

a. Multi-parameter display on the same screen. ORP value, input mV number (or output current), temperature, time, and status can be displayed on the same screen at the same time.

b. Historical curve. The measurement data is stored automatically every 5 minutes, and the ORP value can be stored continuously for one month.

c. Notepad function. Notepad faithfully records the operation use of the meter and the time of alarm occurrence, which is easy to manage.

d. Monitoring electrode function. The way, time and result of each calibration are recorded for easy inquiry and analysis of electrode change pattern.

e. Digital clock function. Provides time reference for various functions.

f. 25°C conversion. For pure water and ammonia-added ultrapure water, 25℃ reference temperature conversion is carried out to realize the display of pH value at 25℃, which is especially suitable for the measurement of various water quality in power plants.

g. Manual current source function. The output current value can be checked and set arbitrarily, which is convenient for testing the recorder and the lower computer.

h. The software sets the current output method. Software selection is 0 to 10mA or 4 to 20mA output.

Machine parameters of ORP meter

Measuring rangeTemperature: 0 to 99.9°C, division value: 0.1°C.
Potential value: -1999~+1999mV, division value : 0.1mV.
Temperature compensation0 to 99.9°C, 25°C as the reference
Measured water sample0~99.9℃, 0.6MPa
Temperature compensation error±1mV
Repeatability error±1mV
Input impedance≥10Ω
Clock accuracy±1min/month
Current isolated output0 to 10 mA (load < 1.5 kΩ); 4 to 20 mA (load < 750 Ω)
Output current error≤±1%FS
Number of data storage1 month (1 point / 5 minutes)
High and low alarm relaysAC220V, 3A
Power supplyAC220V±22V, 50Hz±1Hz
Protection classIP65
Overall dimensions146 (L) × 146 (W) × 108 (D) mm
Opening size138 x 138 mm
Weight0.8 kg
Operating conditions.Ambient temperature 0~60℃ relative humidity <85%

Type of ORP meter

a. According to the portability, the ORP meter is divided into portable redox potentiometer, desktop redox potentiometer, and pen-type redox potentiometer.

b. According to the usage, the ORP meter is divided into laboratory redox meter, industrial online redox potentiometer, etc.

c. According to the advanced degree, the ORP meter is divided into economic redox potentiometer, intelligent redox potentiometer, precision redox potentiometer, and digital redox potentiometer.

d. Pen-type redox potentiometers are generally made into a single range, the measurement range is narrow, for the special simple instrument.

e. Portable and benchtop redox potentiometers have a wide measurement range and are both commonly used instruments, the difference being that the portable is DC powered and can be carried to the field. Laboratory redox potentiometers have a wide measurement range, many functions, and high measurement accuracy.

Industrial redox meters are characterized by good stability, reliable operation, certain measurement accuracy, strong environmental adaptability, strong anti-interference capability, analog output, digital communication, upper and lower limit alarm, control functions, etc.

Use of ORP meter

a. Before use, you need to insert the plug of the platinum electrode into the electrode socket on the instrument and clip a small clip on the platinum electrode to the lead wire of the glycerol electrode.

b. The electrode is inserted into the solution and the power switch is turned on to measure the reading.

c. The measured equilibrium potential, plus the potential value of the reference electrode at that temperature, is the Eh value.

d. The potential measurement range is -1999mV-1999mV, with a small reading of 1mV.

Precautions of ORP meter

a. Turn the power switch to the off position when not in use to prolong the life of the battery.

b. The surface of the platinum electrode is often treated as required. It is the key to the correct determination of Eh.

c. The saturated KCl in the saturated mercury electrode must be kept saturated, otherwise, the potential will not be right.

d. The instrument must be kept clean and dry when in use.

How to buy ORP meter?

ANTITECK provide lab equipment, lab consumable, manufacturing equipment in life sciences sector.
If you are interested in our ORP meter or have any questions, please write an e-mail to, we will reply to you as soon as possible.

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