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What Are The Influencing Factors Of Permanent Deformation Of Hydraulic O-rings?

Apr 28, 2018

1. There are several reasons for the deformation of the o-rings, among which there is an important influence on the temperature. High temperatures accelerate the aging of rubber materials.


2. There are many factors affecting the hydraulic o-ring. Now we introduce the influence of temperature. The higher the working environment temperature, the greater the compression set of the o-ring. When the deformation rate is 40% or more, leakage occurs. Therefore, the heat resistance of several compounds is limited to 70°C for nitrile rubber, 100°C for EPDM, and 140°C for fluoro rubber. The initial stress value formed in the O-ring's rubber material due to compression deformation will gradually decrease as the O-ring's relaxation process and temperature drop effect disappear.


3, the temperature is too high or too low hydraulic o-ring will have an impact, China's standard rubber material O-ring size changes at different temperatures in the table. The O-ring of hydraulic o-rings of the same material has a lower compression set rate of O-rings with large cross-sectional diameters at the same temperature.


4. Hydraulic o-rings operating at sub-zero temperatures may have their initial compression reduced or completely lost due to a sharp drop in temperature. In the case of -50~-60°C, the rubber material that does not tolerate low temperatures will completely lose the initial stress; even if the rubber material is resistant to low temperatures, the initial stress at this time will not be greater than 25% of the initial stress at 20°C. This is because the initial compression of the hydraulic o-ring depends on the linear expansion coefficient. Therefore, when selecting the initial compression amount, it must be ensured that there is still sufficient sealing ability after stress reduction due to relaxation and temperature drop. O-rings operating at subzero temperatures should pay particular attention to the recovery index and deformation index of rubber materials.


5, in the design, should try to ensure that the hydraulic O-ring has a suitable working temperature, or use high-temperature, low-temperature hydraulic O-ring material, in order to extend the service life