Rubber Buna-N
The rated temperature range of the rubber valve seat is -18 ℃ ~ 100 ℃. Usually also called NBR, NITRILE, or HYCAR. It is an excellent general-purpose rubber material suitable for water, gas, oil and grease, gasoline (except gasoline with additives), alcohol and glycol, LP 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) rubber valve seat is -18℃~82℃. Its composition complies with CFR Standards Part 21, Section 177.2600. Its scope of use is the same as conventional rubber but requires FDA (U.S. Food and Drug Administration) certification.
Ethylene-propylene rubber EPDM
The rated temperature range of the ethylene-propylene rubber valve seat is -28 ℃ ~ 120 ℃. EPDM is the abbreviation of its components, which is a terpolymer of ethylene, propylene and diene. It is also commonly called EPT, Nordell, and EPR. It has excellent ozone resistance and weather resistance, good electrical insulation properties, and good resistance to polar capacitors and inorganic media. Therefore, it can be widely used in HVAC industry, water, phosphate, alcohol, ethylene glycol, etc. Ethylene propylene rubber valve seats are not recommended for use with hydrocarbon organic solvents and oils, chlorinated hydrocarbons, turpentine, or other petroleum greases. The rated temperature range of food-grade ethylene-propylene rubber valve seat is -28 ℃ ~ 120 ℃. Its composition complies with CFR Standards Part 21, Section 177.2600. Its scope of use is the same as conventional rubber but requires FDA (U.S. Food and Drug Administration) certification.
Polytetrafluoroethylene PTFE
The rated temperature range of the polytetrafluoroethylene valve seat is -32℃~200℃. Excellent high temperature resistance and chemical corrosion resistance. Because PTFE has high density and excellent anti-permeability, it can also prevent corrosion from most chemical media. Conductive PTFE is a modified PTFE product that allows electrical current to pass through the lining and thereby cancels the insulating properties of PTFE. Because of its conductive properties, conductive PTFE cannot use electric spark to test its quality.
Reinforced polytetrafluoroethylene RTFE
RTFE is a modified form of PTFE material. Although pure PTFE has a very low friction coefficient (0.02~0.04), it has a huge amount of wear. Moreover, due to its easy creep, poor mechanical properties, low load-bearing capacity, and poor dimensional stability, its use as a friction material has great limitations. Only modification can meet the special requirements of various industries for wear-resistant sealing materials through material compounding. In order to improve the wear resistance of PTFE, some wear-resistant substances can be incorporated such as glass fiber, carbon fiber, graphite, molybdenum disulfide, Bronze powder and some organic compounds form network nodes in the PTFE layered structure, thereby improving stiffness, thermal conductivity, creep resistance, and greatly improving wear resistance.
Fluorine rubber Viton
The rated temperature of the fluorine rubber valve seat is -18℃~150℃. Viton is a registered trademark of DuPont, and Fluorel is a registered trademark of 3M Company equivalent to fluorine rubber. This material has high temperature resistance and excellent resistance to chemical corrosion. Suitable for hydrocarbon products, low and high concentration mineral acids, but cannot be used in steam media and water (poor water resistance).
Ultra-high molecular weight polyethylene UHMWPE
The rated temperature range of ultra-high molecular weight polyethylene valve seats is -32℃~88℃. This material has better low temperature resistance than PTFE, but still has excellent chemical resistance. Ultra-high molecular weight polyethylene also has good wear resistance and anti-corrosion properties and can be used in high-wear applications.
Silicon copper rubber Silicone
Silicon copper rubber is a polymer whose main chain is composed of silicon and oxygen atoms and has organic groups. The rated temperature range is -100℃~300℃. It has good heat resistance and temperature resistance, excellent electrical insulation properties and high chemical inertness. Suitable for organic acids and low-concentration inorganic acids, dilute alkali and concentrated alkali. Disadvantages: low mechanical strength. Post-vulcanization is required.
Graphite
Graphite is a crystal of carbon. It is a non-metallic material with a silver-gray color, soft texture and metallic luster. Mohs hardness is 1~2, specific gravity is 2.2~2.3, and its bulk density 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 strong electrical conductivity. It has special oxidation resistance, self-lubrication and plasticity at high temperatures, as well as good electrical conductivity, thermal conductivity and adhesion. It can be used as a filler or performance improver in rubber, plastics and various composite materials to improve the wear resistance, pressure resistance or conductivity of the materials. Graphite is usually used to make valve sealing gaskets, packings and valve seats. The melting point of graphite is extremely high. It begins to soften and tends to a molten state at 3000°C under vacuum. At 3600°C, graphite begins to evaporate and sublimate. The strength of general materials gradually decreases at high temperatures. However, when graphite is heated to 2000°C, its On the contrary, the strength is doubled compared with normal temperature, but the oxidation resistance of graphite is poor and the oxidation rate gradually increases as the temperature increases.
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