• Speed of movement
The adaptability of different materials to the speed of mechanical motion is not the same. For static sealing, there is no relative movement between the seal and the sealed part, so the wear resistance and hardness of the material are not high requirements. But for dynamic seal, to be limited by its sealing speed and pressure, some ordinary materials, can not adapt to high-speed mechanical operation.
The o-ring material is also very sensitive to working pressure. The material is different, and the pressure that the o-ring can bear is different. If the medium is raw material oil, the working pressure that it bears is smaller. If it is water, oil, and other mixed liquids, the working pressure is beyond the scope of the material, which will not only lead to leakage but also reduce the service life of the sealing ring.
Temperature also has a great impact on the material of the o-ring the temperature is too high or too low is not good, too high will make the tensile degree and the hardness of the o-ring reduce; If the temperature is too low, it will make the seal ring very brittle and easy to crack. Each kind of o-ring material has its suitable temperature range, in the design of material selection must pay attention.
• Medium compatibility
The compatibility of the two mediums has a very important role in the selection of seal materials. Some materials will be directly in contact with the medium. If there is no good compatibility between them, it will not only damage the o-ring but also pollute the sealing medium. Therefore, the material of the o-ring can not be eroded, nor can it produce chemical changes with the medium.
Material hardness is the most important index to evaluate the sealing performance, which determines the amount of tightening and groove extrusion gap, to prevent the plastic deformation of the o-ring under pressure. High-hardness material is strong, in the sealing process due to the impact of the environment and force, there will be gaps.