Guide to Electrode Material Selection for Electromagnetic Flowmeters
Many users are concerned about whether an electromagnetic flowmeter can work properly under specific working conditions. Correctly selecting the electrode material is key to ensuring measurement stability and extending service life. This article summarizes the corrosion resistance performance of common electrode materials to help you make a reasonable choice based on medium characteristics.
Common Electrode Materials and Their Applicable Working Conditions
Common electrode materials on the market include: 316L, titanium, platinum, Hastelloy B (HB), Hastelloy C (HC), tungsten carbide, etc. Their characteristics are introduced below.
316L
316L is suitable for measuring domestic water, industrial water, municipal sewage, and mildly corrosive media in organic acids.
Titanium (Ti)
Titanium can resist corrosion from seawater, various chlorides and hypochlorites, oxidizing acids (including fuming nitric acid), organic acids, alkalis, etc. However, it is not resistant to corrosion by relatively pure reducing acids (such as sulfuric acid and hydrochloric acid). If the acid contains oxidants (such as nitric acid, iron ions, or copper ions), its corrosion resistance is greatly reduced.
Platinum (Pt)
Platinum is suitable for almost all acid, alkali, and salt solutions, and also has excellent corrosion resistance to various acids.
Hastelloy B (HB)
Hastelloy B has good corrosion resistance to hydrochloric acid of all concentrations below the boiling point, and also resists corrosion from sulfuric acid, phosphoric acid, hydrofluoric acid, organic acids and other non-oxidizing acids, alkalis, and non-oxidizing salt solutions.
Hastelloy C (HC)
Hastelloy C can resist oxidizing acids, such as nitric acid, mixed acids, or mixed media of chromic acid and sulfuric acid, and also resists corrosion from oxidizing salts or media containing other oxidants, such as hypochlorite solutions above normal temperature and seawater.
Tungsten Carbide (WC)
Tungsten carbide has good wear resistance and can be used for measuring highly abrasive media, such as ore slurry.
Key Points for Electrode Material Selection
When selecting electrode materials, factors such as medium corrosiveness, abrasiveness, temperature, and concentration must be comprehensively considered. The following table summarizes the applicable and non-applicable working conditions for each material for selection reference.
| Electrode Material | Applicable Media | Non-Applicable Media |
|---|---|---|
| 316L | Domestic water, industrial water, municipal sewage, mildly corrosive media in organic acids | Strongly corrosive media |
| Titanium | Seawater, chlorides, hypochlorites, oxidizing acids (including fuming nitric acid), organic acids, alkalis | Relatively pure reducing acids (sulfuric acid, hydrochloric acid); corrosion resistance decreases in acids containing oxidants |
| Platinum | Almost all acid, alkali, and salt solutions | —— |
| Hastelloy B | Hydrochloric acid of all concentrations below the boiling point, sulfuric acid, phosphoric acid, hydrofluoric acid, organic acids and other non-oxidizing acids, alkalis, non-oxidizing salt solutions | Oxidizing acids |
| Hastelloy C | Oxidizing acids (nitric acid, mixed acids, mixed media of chromic acid and sulfuric acid), oxidizing salts, corrosion containing other oxidants, hypochlorite solutions, seawater | Reducing acids |
| Tungsten Carbide | Highly abrasive media, such as ore slurry | —— |
Summary
Correctly selecting the electrode material can significantly improve the measurement accuracy and service life of electromagnetic flowmeters. It is recommended to refer to the above guide for selection based on actual medium characteristics. If you have any questions, you can consult professional technical personnel.
