O-ring is a simple structure, wide specifications, the need for a large number of a sealed product.
O-ring seal quality of life depends on dimensional accuracy and rubber. Generally require the rubber material has a certain mechanical strength, tear resistance and good heat resistance, oil resistance, chemical resistance and the use of conditions to have a smaller compression permanent deformation, is its main indicator.
According to the use of requirements, generally have heat, oil requirements, the use of rubber to the most.
Require high temperature (such as 150 ~ C-l90 ℃) oil seal products can use acrylic rubber. Requirements for higher temperature oil-resistant rubber products with fluorine rubber, heat-resistant silicone rubber.
When the working pressure is high, the method of increasing the hardness of the O-ring compound is to increase the filling amount of the carbon black, but the filling amount is too high, the mixing is difficult and the basic physical properties of the vulcanizate are damaged,
In the case of the use of the same rubber, such as nitrile rubber, in order to improve the heat and oil resistance, reduce the compression of permanent deformation, can be used peroxide (such as the use of DCP) curing system or effective sulfur vulcanization system (low sulfur high) The These two kinds of curing system can generate more carbon-carbon bond cross-linked structure and single sulfur bond cross-linking structure, effectively improve the heat resistance of vulcanized rubber and oil resistance, reduce the compression of permanent deformation.
O-type sealing ring heat-resistant, oil-resistant compound formula filling system, the use of less active thermal cracking carbon black, sprayed carbon black or semi-reinforcing carbon black, the characteristics of these carbon black is coarse particles , Rubber elasticity is good, low heat, low compression deformation, and a large number of filling, reducing the cost of plastic materials. Such as the use of O-ring in the dynamic seal conditions, the need to increase the tear resistance, and can be part of the high activity of high wear-resistant carbon black.
Viton rubber is self-reinforcing rubber, such as filling the activated carbon black but reduce the mechanical properties of the compound, so generally filled with a small amount of less active coarse particles of hot cracking carbon black or spray carbon black.
O-rings are the most commonly used seals in seals. However, due to the selection, groove design, processing and assembly on the improper, often caused by oil spills, can be described as small pieces of bad events.
O-ring materials are mainly butyl nitrile rubber NBR and fluorine rubber FKM, fluorine rubber is more suitable for high temperature conditions.
In addition to the material, O-ring is a very important indicator of its hardness, generally used Shaw hardness to represent, ranging from 60 to 90 or so, the greater the value that the higher the hardness. In the same pressure, the higher the hardness, anti-extrusion (deformation or even tear) the stronger the ability. Therefore, you should use the higher hardness of the O-ring.
O-ring groove design has the relevant national standards, the main split seal, axial static seal and radial static seal three. Flange, box cover, etc. O-ring with axial compression easier to assemble and ensure the sealing performance. In addition, China's national standard trench size standards have been significantly behind, such as the national standard by the internal pressure of the O-ring groove diameter is equal to the O-ring diameter, and PARKER flange connector O-ring groove diameter Less than O-ring outer diameter.
O-rings can not use the surface sealant sealant, you can apply a small amount of butter on the O-ring so that it does not fall off. In the maintenance, should be based on the size of the groove to determine the O-ring specifications, not the thicker the better diameter.
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