This section provides overview, applications, and principles of ph meters. Also, please take a look at the list of 10 ph meter manufacturers and their company rankings.
Table of Contents
A pH meter is a device that measures the pH of a liquid. pH is one of the indicators of water quality and represents the hydrogen ion concentration of a liquid. For example, tap water is classified as neutral, carbonated water and stomach acid as acidic, and lime water and soapy water as alkaline.
A simple method of measuring pH is the colorimetric method using litmus test paper. However, to obtain a more accurate pH value, a pH meter is required. pH meters mainly use glass electrodes and are called the glass electrode method.
pH meters are mainly used to measure pH at waste incineration plants, boilers, and thermal power plants where combustion is used, as well as at construction and civil engineering works and concrete plants where wastewater is discharged. pH meters are also installed to constantly measure and monitor for abnormal pH levels.
In the food industry, there are many food products the taste and safety are affected by pH. Each food has its own pH level, and if the pH level is not appropriate, problems can occur, such as loss of flavor or contamination by foreign substances.
The pH system in the general glass electrode method uses two types of electrodes to measure pH: a glass electrode and a comparison electrode. The pH can be measured by measuring the potential difference between these two electrodes.
If a pH difference occurs between the inside and outside of the thin glass film, a potential difference corresponding to that difference is generated. Theoretically, a pH difference of 1 in a 25°C solution generates an electromotive force of approximately 59 mV. Since the liquid in the glass electrode is usually a liquid with a pH of 7, the pH of the target solution can be determined by measuring the electromotive force.
To measure electromotive force as described above, another electrode is needed to serve as a reference electrode. This is called a comparison electrode. In the comparison electrode, the liquid inside the electrode is in contact with the test solution through the liquid entanglement zone, and the potential hardly changes even if the test solution changes. However, ideally, the electrode's internal liquid should always flow toward the test solution at the liquid-fluid junction, so the internal liquid level should be higher than the test solution level by opening the internal liquid refill port of the comparison electrode during measurement.
When measuring pH, calibration with a standard solution is required. Buffer solutions are used as standard solutions, and there are five types of standard solutions as specified by JIS. Since a pH difference of 1 results in a small potential difference of approximately 59 mV, calibration using these standard solutions first ensures accurate measurement when measuring the electromotive force caused by the pH difference.
Generally, a pH meter consists of an electrode and a temperature sensor for temperature compensation. Glass is used as the electrode, and pH is confirmed by measuring the potential difference generated between the two electrodes, the glass electrode and the reference electrode.
Platinum/hydrogen electrodes have been used as the measuring electrode in pH meters, but these electrodes are no longer commonly used. On the other hand, it is used as a reference electrode to obtain highly accurate measurement results.
Glass electrodes are now used to accommodate the increasingly diverse range of solutions to be measured. The glass electrode contains an internal buffer solution in a pH-sensitive glass membrane, which passes through an internal conducting electrode to measure the potential. The outer electrode tube must have high alkali resistance and several times the glass membrane's electrical resistance.
In the past, pH meters used two electrodes, a glass electrode (measuring electrode) and a reference electrode, in pairs. However, a compound electrode that combines the measuring and reference electrodes into one has been invented and used in many settings. In the composite electrode, a reference electrode is concentrically attached to the outside of the measuring electrode.
When growing crops, it is necessary to check the pH of the soil to see if it is on the acidic or alkaline side. For example, tea is acidic at pH 5, potatoes are slightly acidic at pH 6, and spinach is neutral at pH 7.
However, measuring soil pH is difficult because it is impossible to stick a glass electrode into the ground as with solutions.
The Ministry of Agriculture, Forestry, and Fisheries (MAFF) has prepared a manual for measuring soil pH, and there is a simple method that uses an indicator. The soil is dried naturally, mixed with tap water, and allowed to stand for 5-10 minutes. The supernatant is collected, and the indicator is added drop by drop. Read the coloration of the test water to determine the corresponding pH.
Portable pH meters are also available, which can be inserted directly into the ground to measure the pH of the soil.
*Including some distributors, etc.
Sort by Features
Sort by Area
Ranking as of January 2023 Globally
Derivation MethodRank | Company | Click Share |
---|---|---|
1 | Global Lab Supply | 23.1% |
2 | Acustrip | 15.4% |
3 | SAE Manufacturing Specialties Corp | 15.4% |
4 | UDY Corp. | 15.4% |
5 | Omega Engineering | 15.4% |
6 | MIDSCI | 7.7% |
7 | Sper Scientific Ltd | 7.7% |
Derivation Method
The ranking is calculated based on the click share within the ph meter page as of January 2023. Click share is defined as the total number of clicks for all companies during the period divided by the number of clicks for each company.Number of Employees
Newly Established Company
Company with a History
This is the version of our website addressed to speakers of English in the United States. If you are a resident of another country, please select the appropriate version of Metoree for your country in the drop-down menu.