Composition and functions of composite electrodes in industrial pH meters
The electrode that combines the glass electrode and reference electrode of a pH meter is called a pH meter composite electrode. The composite electrode shell of an industrial pH meter made of plastic is called a plastic shell pH composite electrode. The composite electrode shell of an industrial pH meter made of glass is called a glass pH composite electrode. The biggest advantage of industrial pH meter composite electrodes is their integration and convenient use.
The structure of industrial pH meter composite electrodes mainly consists of electrode balls, glass support rods, internal reference electrodes, internal reference solutions, shells, external reference electrodes, external reference solutions, liquid interfaces, electrode caps, electrode wires, sockets, etc.
⑴ Industrial pH meter composite electrode bulb: It is made by melting and blowing lithium glass with hydrogen function, forming a spherical shape, with a film thickness of about 0.1-0.2mm, and a resistance value of<250 megaohms (25 ℃).
⑵ Glass support tube for composite electrodes of industrial pH meters: It is a glass tube body that supports pH meter electrode bubbles, made of lead glass with excellent electrical insulation, and its expansion coefficient should be consistent with that of pH meter electrode bubble glass.
The internal reference electrode of the industrial pH meter composite electrode is a silver/silver chloride electrode, which is mainly used to extract the potential of the pH meter electrode. It is required to have a stable potential and a small temperature coefficient.
(4) Internal reference solution for industrial pH meter composite electrode: An internal reference solution with a zero potential of 7 pH, which is a mixed solution of neutral phosphate and potassium chloride. The pH value of the glass pH meter electrode and reference electrode to establish zero potential in the battery mainly depends on the pH value of the internal reference solution and the concentration of chloride ions.
(5) Industrial pH meter composite electrode plastic shell: The pH meter electrode plastic shell is a shell that supports the glass electrode and liquid interface, and contains an external reference solution. It is formed by polycarbonate plastic pressing.
The external reference electrode of the industrial pH meter composite electrode is a silver/silver chloride electrode, which provides and maintains a fixed reference potential, requires stable potential, good reproducibility, and low temperature coefficient.
(7) External reference solution of composite electrode of industrial ph meter: 3.3mol/L potassium chloride gel electrolyte, which is not easy to lose and does not need to be added.
The sand core liquid interface of industrial pH meter composite electrode: The liquid interface is the connecting component between the external reference solution and the measured solution, and requires stable permeability.
Industrial pH meter composite electrode wire: It is a low-noise metal shielding wire, with the inner core connected to the inner reference electrode and the shielding layer connected to the outer reference electrode.
