Selection of the material of electrode and lining
Selection of Electrode Material
On the basis of the corrosiveness of measured media, users determine to select the electrode material. For general media, select electrode material by referring to the handbook of antiriot material. For media of mixed acids & complex, have to make a test of hanging for choosing electrode material.
Corrosion-resistance of electrode materials
Electrode Material |
Corrosion Resistance |
Acid-proof steel |
It is stronger corrosion resistance for nitric acid, <5%sulphuric acid, boiling, phosphoric acid, formic acid, alkaline solutions, sulphurous acid, salt solution and acetic acid under certain pressure and is wildly used in field of petro-chemistry, urea and vinylon. |
Hastelloy C |
Corrosion-resisting for oxyacids; such as nitric acid, mixed acids and mixed liquid with chromic & sulphuric acid for oxy-salts of Fe+++ ,Cu++ and other oxygenants, such as hypochlorite solution over atmospheric temperature and oil-water mixed solution. |
Titanium |
Corrosion-resisting for oil-water solution, various chlorides & Sub-chlorates, oxyacids (include fuming nitric acid), organic acid & alkaline. Not corrosion-resisting for purer reducibility acid (such as: sulphuric acid, hydrochloric acid). If its containing oxygenants, acid's corrosion is lower strongly. |
Tantalum |
Has good corrosion-resisting and being similar to glass. Almost corrosion-resisting for all chemical medias, except hydrofluoric acid, fluming sulphuric acid and alkaline. |
Platinum |
Corrosion-resisting for all chemical medias. |
Selection of Lining Materials
To select the lining material in the light of corrosiveness, wearability and temperature of metered midia. Neoprene has good abrasion-resisting property and is suitable for measuring the general weak acids and weak alkaline under 80ˇăC. PTFE is suitable for measuring the concentrated acids and alkaline except for hot phosphoric acid under 180ˇăC, and poor wearability. Polyurethane rubber has excellent abrasive resistance and is poor corrosion-resisting for acid & alkaline. The media's temperature must be under 65ˇăC.
The property and purpose of general lining material
Lining material |
Main property |
Purpose |
PTFE |
1. It is a most stable chemical material in Plastic & corrsion-resising & against boiling hyd r ochloric acid, sulphuric acid, nitric acid ,aquaregia, strong alkaline & each organic solvent. |
1. 40ˇăC ˇ« 180ˇăC |
Neoprene |
1. Having excellent elasticity & stronger tearing force, good tear-proof. |
1. < 80ˇăC |
Polyurethane |
1. Having excellent wearability (is about ten times as strong as natural rubber ) |
1. < 80ˇăC |
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