Nitrile rubber (NBR)
The rated temperature range of nitrile rubber valve seats is -5°C to 80°C. It is also commonly known as NBR, NITRILE, or HYCAR. It is an excellent general-purpose rubber material suitable for water, gas, petroleum and lubricating grease, gasoline (except gasoline with additives), alcohol and ethylene glycol, liquefied petroleum gas, propane and butane, fuel oil, and many other media. It also has good wear resistance and deformation resistance.
Ethylene propylene diene monomer (EPDM) rubber
The rated temperature range of EPDM rubber valve seats is -5°C to 100°C. EPDM is an abbreviation for its components, namely ethylene, propylene and diene terpolymers, and is also known as EPT, Nordel, and EPR. It has excellent ozone resistance and weather resistance, good electrical insulation properties, and is resistant to polar solvents and inorganic media. Therefore, it can be widely used in the HVAC industry, water, phosphate esters, alcohol, ethylene glycol, etc. EPDM rubber valve seats are not recommended for use in hydrocarbon organic solvents and oils, chlorinated hydrocarbons, turpentine, or other petroleum-based oils.
Polytetrafluoroethylene (PTFE)
The rated temperature range of polytetrafluoroethylene valve seats is -20℃ to 180℃. It has excellent high-temperature resistance and chemical corrosion resistance. Due to the high density of polytetrafluoroethylene, it has good anti-permeability and can also prevent corrosion by most chemical media.
Conductive polytetrafluoroethylene is an improved type of polytetrafluoroethylene product that allows current to pass through the lining and thus eliminates the insulating property of polytetrafluoroethylene. Due to its conductive performance, conductive polytetrafluoroethylene cannot be inspected for quality by electrical spark testing.
The rated temperature of the fluorine rubber VITON valve seat is -10℃ to 120℃. VITON is a registered trademark of DuPont, and Fluorel is a registered trademark of 3M equivalent to fluorine rubber. This material has high temperature resistance and excellent chemical corrosion resistance. It is suitable for hydrocarbon products, low and high concentration mineral acids, but not for steam media and water (poor water resistance).
Ultra-high molecular weight polyethylene (UHMWPE)
Graphite is a crystalline form of carbon and a non-metallic material. It has a silver-gray color, is soft in texture, and possesses a metallic luster. Its Mohs hardness is 1 to 2, with a specific gravity of 2.2 to 2.3, and its bulk density is generally 1.5 to 1.8. Graphite has unique physical and chemical properties such as high temperature resistance, oxidation resistance, corrosion resistance, thermal shock resistance, high strength, good toughness, high self-lubrication, strong thermal and electrical conductivity. At high temperatures, it has special oxidation resistance, self-lubrication, and plasticity, as well as good electrical and thermal conductivity and adhesion. It can be used as a filler or performance modifier for rubber, plastics, and various composite materials to enhance their wear resistance, compressive strength, or conductivity. Graphite is commonly used to make sealing gaskets, packing, and valve seats for valves.
Graphite has an extremely high melting point. It begins to soften and tend towards a molten state only at 3000℃ in a vacuum, and starts to evaporate and sublime at 3600℃. While the strength of most materials gradually decreases at high temperatures, the strength of graphite doubles when heated to 2000℃ compared to its strength at room temperature. However, graphite has poor oxidation resistance and its oxidation rate gradually increases with rising temperature.
Polyphenylene sulfide (PPL) is a material obtained by adding some synthetic substances to polytetrafluoroethylene. Its performance is better than that of pure polytetrafluoroethylene. PPL can be used continuously at 260℃ and has a maximum service temperature of 230-280℃. It features an extremely low coefficient of friction, excellent wear resistance and outstanding chemical stability.