How to Resolve Minor Problems of pH Meter Electrodes
① What materials are electrodes made of? The outer casings of pH meter electrodes are generally available in two types: PC plastic (polycarbonate) casing and glass casing. PC casings are resistant to collision and impact, suitable for temperatures below 80°C, but susceptible to corrosion in strong alkaline solutions and some media. Glass casings are suitable for temperatures from 0 to 150°C and generally resist corrosion except in hydrofluoric acid solutions, yet they are fragile. Other materials include stainless steel, polytetrafluoroethylene, and metals.
② What are the different applications of electrodes made from various materials? PC material (polycarbonate): PC casings resist impact and collision, usable below 80°C. Polytetrafluoroethylene (PTFE) electrode: corrosion-resistant, known as "plastic king", resistant to most organic solvents. Glass electrode: high temperature resistant and corrosion resistant, but fragile. For media without HF and with temperatures between 0–100°C, stainless steel electrodes can be used. Media containing organic solvents: PTFE electrodes can be selected; they can withstand high temperatures of around 280°C. The maximum temperature for a pH electrode can reach 130°C. Imported electrodes are recommended for temperatures above 130°C.
③ What is the service life of electrodes under normal use? Generally, electrodes last for half a year to one year, depending on working conditions. Some can be used for 1.5 to 2 years. Imported electrodes may last 3 to 5 years, but they are expensive.
④ How to protect electrodes?
⑴ The glass membrane at the lower end of the glass electrode is fragile. Avoid contact with hard objects. ⑵ For first-time use, soak the spherical glass bulb in distilled water overnight. Keep it immersed in distilled water when not in use to simplify soaking procedures for next use.
⑶ When measuring strongly alkaline solutions, complete the operation as quickly as possible and rinse immediately after measurement to prevent the alkali from corroding the glass membrane.
⑷ The glass membrane must not be contaminated with oil. If oil contamination occurs, first soak the electrode in alcohol, then in ether or carbon tetrachloride, followed by rinsing with water and immersion in water.
⑸ The glass tube on the electrode plug has excellent insulation performance. Keep it away from chemicals and oil stains.
