How To Select Proper O-ring For Hydraulic System
Nov 23, 2022
O-rings are available in a variety of sizes and materials, usually for specific applications. O-rings are particularly important for hydraulic systems because they seal under pressure. O-ring is used to prevent leakage and prevent external pollutants from seeping into the hydraulic system. The following are the specifications, materials, maximum pressure and operating temperature ranges of o-rings used in hydraulics.
Product specifications
There are several factors to be considered in selecting the correct o-ring in the hydraulic system. The size of O-ring is determined by the inner diameter, outer diameter and cross section. The inner diameter and outer diameter are the distances from the center of the O-ring to the inner and outer rings of the O-ring respectively. The length of the inner diameter and outer diameter of the o-ring ranges from a few millimeters to one meter or more. When choosing the inner diameter of o-ring, some space should be reserved to solve the problem of thermal expansion.
The stretching rate of o-ring shall not exceed 5%, because over stretching will cause the cross section of o-ring to flatten. The cross section of o-ring varies from several millimeters to tens of millimeters. When selecting o-ring for hydraulic application, it is very important to know the depth of purchase. Only when the cross section of the selected o-ring is correct, can the extrusion and tear problems be avoided, so as to ensure the sealing effect.
Material Science
O-ring can be made of various materials, including NBR, EPDM, FKM, VMQ, etc
Fluororubber o-ring has extremely high temperature resistance, grease resistance, combustion resistance, resistance to silicone oil and many other media, which is very suitable for aviation applications. Increasing the fluorine content in FKM will increase the chemical resistance, but the low temperature resistance will be weakened. Fluoroelastomer can be used with non flammable hydraulic oils, and in some cases is a suitable choice for hydraulic applications.
