What non-metallic materials are commonly used in valves?
CLICLS：517
Buna-n nitrile butadiene rubber
Nitrile rubber seat temperature rating range from -18 ℃ to 100℃. Often also called NBR, NITRILE, or HYCAR. It is an excellent general-purpose rubber material suitable for water, gas, petroleum and 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.
Food grade (FG) NBR seats are rated from -18 ℃ to 82℃. Its composition conforms to CFR standard part 21, Section 177.2600. Its application scope is the same as that of conventional nitrile butadiene rubber but requires FDA approval.
Ethylene-propylene rubber EPDM
Epr seat rated temperature range from -28 ℃ to 120℃. EPDM is a terpolymer of ethylene, propylene, and diene, commonly known as EPT, Nordell, or EPR. Excellent ozone resistance and weather resistance, good electrical insulation performance, good resistance to polar capacitors and inorganic media. Therefore, it can be widely used in the HVAC industry, water, phosphate ester, alcohol, glycol and so on. Ethylene propylene rubber seats are not recommended for use in hydrocarbon organic solvents and oils, chlorinated hydrocarbons, turpentine, or other petroleum oils.
Food grade EPR seat rated temperature range -28 ℃~120℃. Its composition conforms to CFR standard part 21, Section 177.2600. Its application scope is the same as that of conventional nitrile butadiene rubber but requires FDA approval.
Polytetrafluoroethylene PTFE
Teflon seats are rated from -32 ° C to 200 ° C. Excellent resistance to high temperature and chemical corrosion. Polytetrafluoroethylene has high density, excellent permeability, but also can prevent the corrosion of most chemical media.
Conductive TEflon is an improved TEflon product that allows an electric current to pass through the lining and thus cancels the insulation properties of teflon. Because of its conductive properties, conductive PTFE quality can not be tested by electric spark.
Reinforced POLYtetrafluoroethylene RTFE
RTFE is a modification of PTFE. Pure PTFE although the friction coefficient is very low (0.02~0.04) but the wear is great, and because of its creep, poor mechanical properties, low bearing capacity, poor dimensional stability and other characteristics, as a friction material use has great limitations. Only modification, through the material composite method to meet the special requirements of wear-resistant sealing materials of all walks of life, in improving the wear resistance of PTFE, can be mixed with some wear-resistant substances such as glass fiber, carbon fiber, graphite, molybdenum disulfide, bronze powder and some organic compounds, They form network nodes in the PTFE layered structure so as to improve the stiffness, thermal conductivity, creep resistance, and greatly improve wear resistance.
Fluorine rubber Viton
Fluorine rubber seats are rated from -18℃ to 150℃. Viton is a registered trademark of DuPont and Fluorel is 3M's equivalent of fluororubber. This material has high temperature resistance and excellent chemical corrosion resistance. Suitable for hydrocarbon products, low and high concentrations of mineral acids, but not for steam media and water (poor water resistance).
Ultra high molecular weight polyethylene UHMWPE
Uhmwpe seats are rated from -32 ° C to 88 ° C. The 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 corrosion resistance, can be used in high wear applications.
Silicon copper rubber Silicone
Silicon copper rubber is a polymer with organic groups whose main chain is composed of silicon oxygen atoms. The rated temperature ranges from -100℃ to 300℃. With good heat resistance and temperature resistance, excellent electrical insulation performance, chemical inertia. Suitable for organic acid and low concentration of inorganic acid, dilute base and concentrated base. Disadvantages: low mechanical strength. Post curing is required.
Graphite Graphite
Graphite is the crystal of carbon, is a kind of nonmetallic material, silver gray color, soft quality, with metallic luster. Mohs hardness is 1~2, specific gravity 2.2~2.3, its bulk density is generally 1.5~1.8. With high temperature resistance, oxidation resistance, corrosion resistance, thermal shock resistance, high strength, good toughness, high self-lubricating strength, heat conduction, electrical conductivity and other unique physical and chemical properties. It has special oxidation resistance, self-lubrication and plasticity at high temperature, and has good electricity, 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, pressure resistance or conductivity of materials. Sealing gaskets, packing and seats of valves are usually made of graphite.
Graphite of high melting point, to 3000 ℃ under the vacuum is to begin to soften tends to melt state, graphite evaporated sublimation to 3600 ℃, the general material under the high temperature strength decreases gradually, while the graphite in the heated to 2000 ℃, its strength is normal temperature double instead, but the difference of oxidation resistance of graphite oxidation rate was gradually increased with the temperature.
