An annular cover consisting of one or several parts is attached to a ferrule or washer of the bearing and contacts another ferrule or gasket or forms a narrow labyrinth gap to prevent leakage of lubricating oil or foreign objects. The sealing ring is a rubber ring with a circular cross section. Because its cross section is O-shaped, it is called an O-ring.
Comparison of material of 11 rubber seals of boiler feed pump
1. NBR nitrile rubber seal
It is suitable for use in petroleum-based hydraulic oil, glycol-based hydraulic oil, diester-based lubricating oil, gasoline, water, silicone grease, silicone oil, etc. It is the most widely used and lowest cost rubber seal. Not suitable for use in polar solvents such as ketones, ozone, nitrohydrocarbons, MEK and chloroform. It is generally used at temperatures ranging from -40 to 120 °C.
2. HNBR hydrogenated nitrile rubber seal
It has excellent corrosion resistance, tear resistance and compression deformation resistance, and it is resistant to ozone, sunlight and weather. More abrasion resistance than nitrile rubber. Suitable for washing machinery, automotive engine systems.
Not recommended for use in alcohols, esters or aromatic solutions. Typical use temperature range is -40-150 °C.
3. SIL silicone rubber seal
It has excellent heat resistance, cold resistance, ozone resistance and insulation properties, but its tensile strength is inferior to that of ordinary rubber and it does not have oil resistance. Suitable for household appliances such as electric water heaters, electric irons, microwave ovens, etc. It is also suitable for all kinds of articles that come into contact with the human body, such as water bottles and water dispensers. Not recommended for use in most concentrated solvents, oils, concentrated acids and sodium hydroxide. Typical use temperatures range from -55 to 250 °C.
4. VITON fluorocarbon rubber seal
Its high temperature resistance is superior to silicone rubber, and it has excellent weather resistance, ozone resistance and chemical resistance. It is resistant to most oils and solvents, especially acids, aliphatic hydrocarbons, aromatic hydrocarbons and animal and vegetable oils. It is suitable for the sealing needs of diesel engines, fuel systems and chemical plants.
It is not recommended for use in ketones, low molecular weight esters and mixtures containing nitrates. Typical use temperature range is -20-250 °C.
5. FLS fluorosilicone rubber sealing ring
Its properties combine the advantages of fluorocarbon rubber and silicone rubber, and are excellent in oil resistance, solvent resistance, fuel oil resistance and high and low temperature resistance. It is resistant to attack by oxygen-containing compounds, aromatic-containing solvents, and chlorine-containing solvents. Typical use temperature range is -50-200 °C.
6. EPDM EPDM rubber sealing ring
Has good weather resistance, ozone resistance, water resistance and chemical resistance. It can be used in alcohols and ketones, and it can also be used for sealing in high temperature water vapor environment. Typical use temperature range -55-150 °C.
7. CR neoprene seals
It is particularly resistant to sunlight and weather. It is not afraid of refrigerants such as dichlorodifluoromethane and ammonia, and is resistant to dilute acid and silicone greases, but has a large amount of expansion in mineral oils with low aniline points. It is easy to crystallize and harden at low temperatures. Applicable to all kinds of environments exposed to the atmosphere, sunlight, ozone and various flame-resistant and chemical-resistant sealing parts.
It is not recommended for use in chemicals such as strong acids, nitrohydrocarbons, esters, chloroforms and ketones. Typical use temperatures range from -55 to 120 °C.
8. IIR butyl rubber seal
It has excellent air tightness, good heat resistance, sunlight resistance, ozone resistance, good insulation performance, good resistance to polar solvents such as alcohols, ketones, esters, etc. It can be exposed to animal and vegetable oils or oxidizable oxides. . Suitable for chemical resistant or vacuum equipment.
It is not recommended for use with petroleum solvents, kerosene or aromatics. Typical use temperatures range from -50 to 110 °C.
9. ACM acrylate rubber seal ring
It has excellent resistance to oil, high temperature resistance and weather resistance, but mechanical strength, compression set and water resistance are slightly poor. Generally used in automotive transmission systems and power steering systems. Not suitable for use in hot water, brake fluid, and phosphate esters. Typical use temperatures range from -25 to 170 °C.
10. NR natural rubber seal
Rubber products have good wear resistance, elasticity, tear strength and elongation. However, it is easy to age in the air, becomes sticky when exposed to heat, easily swells and dissolves in mineral oil or gasoline, and is alkali-resistant but not resistant to strong acid. It is suitable for use in liquids such as automobile brake oil and ethanol with hydroxide ions. The general temperature range is -20-100 °C.
11. PU polyurethane rubber sealing ring
The mechanical properties of polyurethane rubber are very good, and the wear resistance and high pressure resistance are far superior to other rubbers. The aging resistance, ozone resistance and oil resistance are also quite good, but it is easily hydrolyzed in a high temperature environment.
Generally used for high pressure and wear resistant sealing. Typical use temperatures range from -45 to 90 °C.
