Pressure Transmitter Diaphragm Selection: Stop Guessing, Start Choosing the Right One
Ever feel confused when selecting a diaphragm for pressure transmitters? A right diaphragm ensures long-term stable operation of your equipment; a wrong one will not only cause diaphragm corrosion and inaccurate measurements, but also lead to costly equipment replacement and production delays. How to choose a diaphragm that is both safe and cost-effective? Don’t worry—we’ll break it down thoroughly here! From Monel, tantalum alloy, titanium alloy to Hastelloy, we’ll explain the key points of different diaphragms. After reading this, you’ll no longer select diaphragms by intuition!
Monel Alloy Diaphragm
Monel alloy consists of 70% nickel and 30% copper (Ni70Cu30). It offers excellent corrosion resistance to hydrofluoric acid, making it the top choice for hydrofluoric acid instrument materials in the fluorochemical industry.
Tantalum Alloy Diaphragm
Metallic tantalum has outstanding corrosion resistance. Except for hydrofluoric acid, fluorine, and fuming nitric acid, it can resist almost all chemical media—including boiling hydrochloric acid, nitric acid, and sulfuric acid below 175°C.
Titanium Alloy Diaphragm
It resists corrosion from various chlorides, hypochlorites, wet chlorine, oxidizing acids (including fuming nitric acid), and organic acids and alkalis. However, it is not resistant to reducing acids such as sulfuric acid and hydrochloric acid.
Hastelloy Diaphragm
Hastelloy is a nickel-chromium-iron-molybdenum alloy, with Hastelloy B and Hastelloy C being the most widely used types.
Hastelloy B contains over 15% molybdenum, providing excellent corrosion resistance to hydrochloric acid of all concentrations at boiling point. It also resists non-oxidizing acids (e.g., sulfuric acid, phosphoric acid, hydrofluoric acid, organic acids), alkalis, and non-oxidizing salt solutions.
Hastelloy C resists oxidizing acids (e.g., nitric acid, mixed acids, or mixtures of chromic acid and sulfuric acid) as well as oxidizing salts.
Diaphragm Selection Guide for Acid and Mixed Acid Media
