The purpose of each O-ring is different. When selecting an O-ring, it is important to consider its working environment and conditions, sealing requirements, physical properties, etc. So, when choosing an O-ring, what specific factors should we consider
1. Working medium and working conditions
When selecting the material of the O-ring, the compatibility with the working medium should be considered first. Secondly, comprehensive consideration should be given to working conditions such as pressure, temperature, continuous working time, and operating cycle at the sealing point. If used in rotating situations, it is necessary to consider the temperature rise caused by frictional heat. Different sealing materials have different physical and chemical properties.
2. Sealing form
According to the type of load, it can be divided into static seal and dynamic seal; According to the sealing purpose, it can be divided into hole sealing, shaft sealing, and rotating shaft sealing; According to its installation form, it can be divided into radial installation and axial installation. When installing radially, for shaft seals, the deviation between the inner diameter of the O-ring and the diameter being sealed should be minimized as much as possible; For sealing holes, the inner diameter should be equal to or slightly smaller than the diameter of the groove. When installing axially, consider the direction of pressure. When subjected to internal pressure, the outer diameter of the O-ring should be approximately 1-2% larger than the outer diameter of the groove; When subjected to external pressure, the inner diameter of the O-ring should be approximately 1% to 3% smaller than the inner diameter of the groove.
3. Other factors affecting sealing performance
① The hardness of the O-ring material is the most important indicator for evaluating sealing performance. The hardness of the O-ring determines the compression amount of the O-ring and the maximum allowable extrusion gap of the groove.
② The maximum allowable extrusion gap is related to system pressure, O-ring cross-sectional diameter, and material hardness. Usually, the higher the working pressure, the smaller the maximum allowable extrusion gap value. If the gap exceeds the allowable range, it will cause the O-ring to extrude or even be damaged.
