Instructions for correctly selecting anti-corrosion materials for electromagnetic flowmeters

Intelligent anti-corrosion electromagnetic flowmeter is a type of flowmeter that is often used in industrial production, because many industrial liquid raw materials are corrosive, such as dilute sulfuric acid, hydrochloric acid, and hydrofluoric acid. For different corrosive media, we must choose the corresponding measuring instrument when measuring. The selection of anti-corrosion materials for intelligent anti-corrosion electromagnetic flowmeters needs to be adapted to the production process flow measurement and control of industrial and agricultural departments such as petrochemicals, steel metallurgy, water supply and drainage, water conservancy irrigation, water treatment, environmental sewage total control, papermaking, medicine, and food. Whether it is from the pipe of the measuring instrument to the measuring electrode, there is a set of strict matching standards. How to correctly select the corresponding materials is a basic knowledge that must be mastered for friends engaged in instrument construction and measurement work. The following is a brief introduction. For detailed material selection and related knowledge, please visit our website: www.harzkj.com, or call 4000-388-535.
 
First of all, let's talk about the selection of anti-corrosion lining for intelligent anti-corrosion electromagnetic flowmeters : There are three key factors in the selection of electromagnetic flowmeter lining materials, that is, the corrosiveness and abrasiveness of the measured medium and the temperature.
 
The lining materials of intelligent electromagnetic flowmeters are mainly: natural rubber; acid-resistant rubber; chloroprene rubber; polyurethane rubber; polytetrafluoroethylene; meshed PFA. Users should choose the appropriate lining material according to the corrosiveness, abrasiveness and temperature of the measured medium.
Application of natural rubber (soft rubber): 1. Good elasticity, wear resistance and tearing force; 2. Resistant to general weak acid and weak alkali corrosion; measuring water and sewage
　　
Application of acid-resistant rubber (hard rubber): Resistant to hydrochloric acid, acetic acid, oxalic acid, ammonia water, phosphoric acid and 50% sulfuric acid, sodium hydroxide, potassium hydroxide at room temperature, but not resistant to strong oxidants, measuring general acid, alkali, and salt solutions
　　
Application of chloroprene rubber (Neoprene): 1. Excellent elasticity, high tearing force, good wear resistance; 2. Resistant to general low-concentration acid, alkali, and salt solutions, but not resistant to oxidizing media; <80℃; measuring water, sewage, mud and slurry.
　　
Application of polyurethane rubber: 1. Excellent wear resistance; 2. Poor acid and alkali resistance <40℃; Measuring neutral and strong wear coal slurry, mud and ore slurry
　　
Application of polytetrafluoroethylene (PTFE): 1. Resistant to boiling hydrochloric acid, sulfuric acid, nitric acid, aqua regia, concentrated alkali and various organic solvents; 2. Good wear resistance, poor bonding performance; -80～+180℃; Measuring concentrated, concentrated alkali, strong corrosive solutions and sanitary media.
Due to the wide variety of media, their corrosiveness is affected by complex factors such as temperature, concentration, flow rate, etc., so this table is for reference only. Users should make their own choices of intelligent electromagnetic flowmeter linings according to actual conditions, and should conduct corrosion resistance tests of the selected materials, such as hanging plate tests, when necessary. .The
 
second is the selection of anti-corrosion electrodes for intelligent anti-corrosion electromagnetic flowmeters : When selecting electrode materials, the corrosion resistance of the measured medium should be considered, which is generally one level higher than the process pipeline material. The grounding ring can be made of the same material as the electrode, or the same material as the process pipeline. When the process pipeline is a metal pipeline and the inner wall has no insulating coating, the grounding ring may not be selected. The explanation is as follows:

1. Stainless steel, code 316L, is used for weakly corrosive media such as industrial water, domestic water, sewage, neutral solutions and weak acids such as carbonic acid and acetic acid.

2. Hastelloy C, code HC, is resistant to oxidizing acids, such as a mixture of nitric acid, chromic acid and sulfuric acid. It is also resistant to corrosion by oxidizing salts or environments containing other oxidants. It has good corrosion resistance to seawater, alkaline solutions and chloride solutions.

3. Hastelloy B, code HB, has good corrosion resistance to non-oxidizing acids, alkalis and salts such as sulfuric acid, phosphoric acid and hydrofluoric acid.

4. Titanium, code Ti, is resistant to corrosion from seawater, various chlorides and hypochlorites and various hydroxides.

5. Tantalum, code Ta, is resistant to corrosion from almost all chemical media except hydrofluoric acid. Because of its high price, it is only used for hydrochloric acid and concentrated sulfuric acid.