What Types of pH Meters Are There and How Are They Classified?
(1) Classified by application scenarios: pH meters can be divided into pen-type pH meters, portable pH meters, laboratory pH meters and industrial pH meters.Pen-type pH meters are mainly used to replace pH test paper, featuring high precision and easy operation. Portable pH meters are designed for field and on-site testing, requiring relatively high precision and complete functions. Laboratory pH meters are high-precision analytical instruments with high accuracy and full functions; some models support printout and data processing. Industrial pH meters are applied for continuous measurement in industrial processes. They not only have measurement and display functions, but also alarm and control functions, with considerations for installation, cleaning, anti-interference and other factors.
(2) Classified by instrument accuracy grade: They are available in grades of 0.2, 0.1, 0.02, 0.01 and 0.001. The smaller the number, the higher the precision.
(3) Classified by readout indication: They are divided into analog pointer type and digital display type. Analog pointer pH meters are rarely used nowadays. However, pointer instruments can show continuous changes of data, so they are still adopted in titration analysis.
(4) Classified by electronic component type: They include transistor type, integrated circuit type and single-chip microcomputer type. Microchip solutions are widely used at present, which greatly reduce instrument size and unit cost, though the chip development cost is high.
What are the components of an acidometer / pH meter?
Potentiometric measurement with an acidometer is an accurate method for pH determination. A pH meter consists of three components:(1) A reference electrode: It maintains a constant potential and acts as a reference for measuring various potential deviations.(2) A glass electrode: Its potential depends on the pH of the surrounding solution.(3) A galvanometer: It can measure tiny potential differences in circuits with high resistance.
The main body of an acidometer is a precision potentiometer. During measurement, the combination electrode is immersed in the test solution. Different electromotive forces are generated according to the acidity (hydrogen ion concentration) of the sample solution. The signal is amplified by a DC amplifier, and finally the pH value of the measured solution is displayed by the readout indicator (voltmeter).
