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Can mass flow controllers be used to control corrosive gases and special gases? How to choose a sealing material?

Mass flow controllers can be used to control a variety of gases, including corrosive gases and special gases, but it should be noted that the use of corrosive gases and special gases requires proper selection of model and seal material. When ordering, the user needs to declare the use of gas to the supplier, so as to avoid serious damages due to errors in selection or selection of sealing materials.
Normally, the wet mass of the gas mass flow controller in contact with the working gas is 316L stainless steel, PTFE, sealing materials, etc. The sealing material is divided into two major categories: metal seal and rubber seal. Metal-sealed materials are generally corrosion-resistant materials such as stainless steel, gold, or nickel. The metal-sealed MFC can be used in principle for any gas, including various corrosive gases and specialty gases. For metallic gases such as boron tribromide, boron trichloride, hydrogen fluoride and other highly corrosive gases and metal oxide gases used for MOCVD, metal-sealed MFC is recommended.
Due to the high price of metal-sealed MFCs and the often low requirements, rubber-sealed MFCs are used. Unless otherwise specified, MFCs are sealed with fluoro rubber and can be used for most acidic and alkaline corrosive gases, such as halogen-based dry gases such as hydrogen chloride. Other special corrosive gases require special rubber. Ammonia - ammonia resistant rubber such as ethylene propylene rubber, neoprene or nitrile; organic solvent vapors (acetone, toluene, etc.) - silicone rubber required; boron tribromide, boron trichloride, Hydrogen fluoride, etc. - Perfluoro rubber is required.

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