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What non-metallic materials are commonly used for valves?


The rated temperature range of nitrile rubber valve seat is - 18 ℃~100 ℃. Also known as NBR, NITRILE, or HYCAR. It is a general-purpose rubber material, suitable for water, gas, petroleum and lubricating grease, gasoline (except gasoline containing additives), alcohol and ethanol, liquefied petroleum gas, propane and butane, fuel oil and many other media. It also has good wear resistance and deformation resistance.  
The rated temperature range of food grade (FG) nitrile rubber valve seat is - 18 ℃~82 ℃. Its composition complies with the CFR Standard, Part 21, Section 177.2600. Its application scope is the same as that of conventional nitrile rubber, but it is subject to FDA certification.  
The rated temperature range of ethylene propylene rubber valve seat is - 28 ℃~120 ℃. EPDM is the abbreviation of its component, namely the terpolymer of ethylene, propylene and olefin, which is also commonly called EPT, Nordell, EPR. Ozone resistance and weather resistance, good electrical insulation, good resistance to polar capacitive agent and inorganic medium. Therefore, it can be widely used in HVAC industry, water, phosphate ester, alcohol, ethanol, etc. Ethylene propylene rubber seats are not used in hydrocarbon organic solvents and oils, chlorinated hydrocarbons, or other petroleum oils.  
The rated temperature range of food grade ethylene propylene rubber valve seat is - 28 ℃~120 ℃. Its composition complies with the CFR Standard, Part 21, Section 177.2600. Its application scope is the same as that of conventional nitrile rubber, but it is subject to FDA certification.  
The rated temperature range of PTFE valve seat is - 32 ℃~200 ℃. High temperature resistance and chemical corrosion resistance. Polytetrafluoroethylene has high compactness, excellent impermeability, and can also prevent corrosion of most chemical media.  
Conductive PTFE is an improved PTFE product, which allows current to pass through the lining and thus cancels the insulation performance of PTFE. Because of its conductive property, the conductive PTFE cannot be tested by electric spark.  
Reinforced PTFE RTFE
RTFE is a modifier of PTFE material. Although the friction coefficient of pure PTFE is very low (0.02~0.04), it has a lot of wear, and because of its easy creep, poor mechanical properties, low bearing capacity, poor dimensional stability and other characteristics, its use as a friction material has great limitations. Only modification can meet the special requirements for wear-resistant sealing materials put forward by all walks of life through material composite. In terms of improving the wear-resistance of PTFE, some wear-resistant materials such as glass fiber, carbon fiber, graphite, molybdenum sulfide, bronze powder and some organic compounds can be added to make them form a network node in the PTFE layered structure, thus improving the stiffness, thermal conductivity, creep resistance, and greatly improving the wear resistance.  
The rated temperature of fluororubber valve seat is - 18 ℃~150 ℃. Viton is a registered trademark of DuPont, and Fluorel is a registered trademark equivalent to fluororubber of 3M. This material has high temperature resistance and excellent chemical corrosion resistance. It is suitable for hydrocarbon products, low concentration and high concentration mineral acids, but not for steam medium and water (poor water resistance).  
The rated temperature range of UHMWPE valve seat is - 32 ℃~88 ℃. This material has better low-temperature resistance than PTFE, but still has excellent chemical resistance. UHMWPE also has good wear resistance and corrosion resistance, and can be used in high wear occasions.  
Silicone copper rubber is a polymer with organic groups, whose main chain is composed of silicon oxygen atoms. The rated temperature range is - 100 ℃~300 ℃. It has good heat resistance and temperature resistance, excellent electrical insulation performance and great chemical inertness. Suitable for organic acid and low concentration inorganic acid, dilute alkali and concentrated alkali. Disadvantages: low mechanical strength. Post vulcanization treatment is required.  
Graphite is a crystal of carbon and a non-metallic material with silver gray color, soft texture and metallic luster. The Mohs hardness is 1-2, the specific gravity is 2.2~2.3, and the unit weight is generally 1.5~1.8. It has unique physical and chemical properties such as high temperature resistance, oxidation resistance, corrosion resistance, thermal shock resistance, high strength, good toughness, high self-lubricating strength, strong thermal conductivity and electrical conductivity. It has special oxidation resistance, self-lubricating and plasticity at high temperature, and has good conductivity, heat conduction and adhesion. It can be used as filler or performance improver for rubber, plastic and various composite materials to improve the wear resistance, compression resistance or conductivity of materials. Generally, graphite is used to make the sealing gasket, packing and valve seat of the valve.  
The melting point * of graphite begins to soften when it reaches 3000 ℃ in vacuum. When it reaches 3600 ℃, the graphite begins to evaporate and sublimate. The strength of ordinary materials gradually decreases at high temperature, while when the graphite is heated to 2000 ℃, its strength is doubled compared with that at normal temperature. However, the poor oxidation resistance of graphite gradually increases with the increase of temperature.


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