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Common seal ring materials: Rubber is the most commonly used sealing material. In addition to rubber, materials suitable for use as sealing materials include graphite, polytetrafluoroethylene, and various sealants. General-purpose rubber sealing material; such rubber sealing products are being used increasingly widely in industries such as defense, chemicals, coal, petroleum, metallurgy, transportation, and machinery manufacturing, and have become essential components and accessories in various sectors. The common materials for rubber sealing products are as follows. 1. Nitrile rubber: Nitrile rubber exhibits excellent resistance to fuel oils and aromatic solvents, but it is not resistant to acids, esters, hydrogen chloride, and similar substances; therefore, oil-resistant sealing products are made using nitrile rubber as the main material. 2. Neoprene: Neoprene has good oil and solvent resistance. It has good resistance to gear oil and transformer oil, but is not resistant to aromatic oils. Neoprene also possesses excellent resistance to weathering and ozone aging. The cross-linking break temperature of neoprene is above 200°C, and it is commonly used to make door and window sealing strips. Neoprene also exhibits good corrosion resistance to inorganic acids. Furthermore, due to its good flexibility and airtightness, neoprene can be used to manufacture diaphragms and sealing components for vacuum applications. Natural rubber: Compared with most synthetic rubbers, natural rubber possesses excellent overall mechanical properties, cold resistance, high resilience, and wear resistance. Natural rubber is not resistant to mineral oils, but it is more stable in vegetable oils and alcohols. In hydraulic braking systems that use a brake fluid composed of a mixture of n-butanol and refined castor oil, the rubber cups and rings used as seals are all made of natural rubber; generally, sealing gaskets are also manufactured from natural rubber. 4. Fluororubber: Fluororubber boasts excellent heat resistance (200–250°C) and oil resistance; it can be used to manufacture cylinder liner seals, rubber rings, and rotary lip seals, thereby significantly extending their service life. 5. Silicone rubber: Silicone rubber boasts excellent resistance to extreme temperatures, ozone, and weathering. It maintains its unique elasticity as well as its resistance to ozone and weathering within an operating temperature range of -70 to 260°C. It is suitable for use in making sealing gaskets required in thermal devices, such as sealing rings for high-intensity light sources and valve gaskets. Due to its oil intolerance, low mechanical strength, and high cost, silicone rubber is not suitable for manufacturing oil-resistant sealing products. 6. Ethylene propylene diene monomer rubber: The main chain of ethylene propylene diene monomer rubber is a fully saturated straight-chain structure without double bonds, while its side chains contain diene groups, which allows it to be vulcanized using sulfur. Ethylene propylene diene monomer rubber possesses excellent resistance to aging, ozone, weathering, and heat (it can be used for extended periods in environments at 120°C), as well as chemical resistance (to alcohols, acids, strong bases, oxidizing agents). However, it is not resistant to the attack of aliphatic and aromatic solvents. EPDM has the lowest density among rubbers and features high fill content, but it lacks self-adhesion and inter-adhesion. Furthermore, EPDM possesses excellent steam resistance, making it suitable for producing steam-resistant diaphragms and other sealing components. EPDM has been widely used in washing machines, components in televisions, and door and window sealing products, as well as in the production of rubber strips for various composite profiles. 7. Polyurethane rubber: Polyurethane rubber boasts excellent abrasion resistance and good airtightness, with a typical operating temperature range of -20 to 80°C. In addition, it has moderate resistance to oil, oxygen, and ozone aging, but it is not resistant to acids, alkalis, water, steam, and the like. Suitable for manufacturing various rubber sealing products, such as oil seals, O-rings, and diaphragms. 8. Chloroether rubber: Chloroether rubber combines the advantages of nitrile rubber, neoprene, and acrylate rubber. It exhibits excellent resistance to oil, heat, ozone, fire, alkalis, water, and organic solvents, as well as good processability; however, its cold resistance is poor. At temperatures that are not too low, chloroether rubber remains an excellent material for manufacturing oil seals, various types of sealing rings, gaskets, diaphragms, and dust covers, among other sealing products. 9: Acrylate rubber: Acrylate rubber exhibits resistance to hot oils (mineral oils, lubricants, and fuel oils), particularly in terms of oil stability at high temperatures; its resistance typically reaches 175°C, and it can withstand temperatures of up to 200°C under intermittent use or for short periods of time. Its drawback is poor cold resistance. Therefore, oil seals suitable for producing high-temperature resistant oils are appropriate for use in non-cold regions, but not suitable as sealing components subjected to tensile or compressive stresses at high temperatures. Nitrile rubber: good oil resistance, heat resistance, and wear resistance. It is widely used in the production of sealing products, but it is not suitable for phosphate-based hydraulic oils and gear oils containing polar additives. -40–120°C, used for manufacturing O-rings and oil seals, suitable for general hydraulic and pneumatic systems. Hydrogenated nitrile rubber: high strength, oil resistance, wear resistance, heat resistance, and aging resistance. -40–150°C, used for high-temperature, high-speed reciprocating and rotary sealing. Rubber-plastic: It has a high elastic modulus and strength, with the same other properties as above. -30–80°C, used for manufacturing \"O\"-rings, \"Y\"-rings, dust seals, etc., for sealing in construction machinery and high-pressure hydraulic systems. Fluororubber: resistant to heat, acids, alkalis, and other chemicals; resistant to oils (including phosphate-based hydraulic oils); suitable for all types of lubricants, gasoline, hydraulic fluids, and synthetic oils. -20–200°C; suitable for sealing applications that require resistance to high temperatures, chemicals, and flammable hydraulic fluids, and is widely used in industries such as metallurgy and power generation. Polyurethane: excellent wear resistance, high strength, and good aging resistance. -20–80°C. Suitable for sealing high-pressure, high-speed systems in construction machinery and metallurgical equipment. Silicone rubber: It has good heat and cold resistance. It has low compressive set but low mechanical strength, operating in the range of -60 to 230°C. Suitable for high-speed rotary seals in high and low temperatures, as well as seals for food processing machinery. Polyacrylate: It has better heat resistance than NBR, and can be used in various lubricants, hydraulic fluids, and petroleum-based hydraulic fluids that contain polar additives; however, its water resistance is poor. -20–150°C; it can be used for various automotive oil seals as well as in different gearboxes and transmission units, and is capable of withstanding medium to high temperatures. Ethylene-propylene rubber: It has good weather resistance, is resistant to aging in air; its oil resistance is average, but it can withstand freon and various refrigerants. -50–150°C, used for sealing in refrigerators and refrigeration equipment. Polytetrafluoroethylene: It has good chemical stability, as well as resistance to heat and cold. It is also resistant to various media such as oils, water, steam, and chemicals. It has high mechanical strength, is resistant to high temperatures and wear, has an extremely low coefficient of friction, and excellent self-lubricating properties. -55–260°C: Used to manufacture wear-resistant rings, guide rings, and retaining rings; it is a commonly used sealing material in machinery, and is widely applied in the metallurgy, petrochemical, construction machinery, and light industrial machinery sectors. Nylon: It has good oil resistance, heat resistance, and wear resistance, as well as high compressive strength and impact resistance; however, its dimensional stability is poor. -40–120°C, used for manufacturing guide rings, support rings, compression rings, and retaining rings. Polyoxymethylene: It has good oil resistance, heat resistance, and wear resistance; it features high compressive strength and excellent impact resistance. It also possesses good self-lubricating properties and dimensional stability, but its flexibility is poor. -40–140°C. Used to make guide rings and retaining rings. Based on the cross-section of the seal ring, seal ring standards can be classified into O-ring seals, star-shaped seal rings, X-shaped seal rings, hollow tube seal rings, V-shaped seal rings, L-shaped seal rings, U-shaped seal rings, Y-shaped seal rings, and custom-shaped seal rings. Based on material, they can be classified into nitrile rubber seals, natural rubber seals, neoprene seals, EPDM seals, hydrogenated nitrile rubber seals, silicone seals, fluororubber seals, and perfluoroelastomer seals. The standard for sealing rings is ID inner diameter * CS wire diameter. The installation requirements for sealing rings: sealing rings are the most important and effective means of addressing leakage problems in hydraulic systems. If the seals in a hydraulic system are of poor quality, unwanted external leakage may occur, and the leaked oil will contaminate the environment ； It may also allow air to enter the oil suction chamber, affecting the performance of the hydraulic pump and the smoothness of the movement of the hydraulic actuation elements. Therefore, the proper selection and design of sealing ring assemblies are very important in the design of hydraulic systems. The requirements for such sealing ring assemblies are as follows: 1. The sealing rings must exhibit good sealing performance within the operating pressure and temperature ranges, and their sealing performance should improve automatically as the pressure increases. 2. The friction between the seal ring assembly and the moving parts should be low, and the coefficient of friction should be stable. 3. The sealing ring has strong corrosion resistance, does not age easily, has a long service life, good wear resistance, and can compensate automatically to a certain extent after wear. 4. It has a simple structure, is easy to use and maintain, which extends the service life of the sealing ring.