What Factors Can Affect The Performance Of O-rings

Hardness of O-ring: The hardness of 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.
O-ring extrusion clearance: The maximum allowable extrusion clearance and system pressure are related to the O-ring cross-sectional diameter and material hardness. Usually, the higher the work 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.
Compression permanent deformation: Another indicator for evaluating the sealing performance of O-rings is the compression permanent deformation of the selected material. Under pressure, the O-ring, as an elastic element, undergoes elastic deformation, and as the pressure increases, permanent plastic deformation also occurs.
O-ring pre compression amount: When the O-ring is installed in the groove, an initial compression amount should be reserved to ensure its sealing performance. For different application scenarios, the pre compression shrinkage relative to the cross-sectional diameter W also varies. Usually, it is about 15% -30% in static seals and about 9% -25% in dynamic seals.
O-ring stretching and compression: When installing an O-ring in a groove, it needs to be stretched or compressed. If the values of stretching and compression are too large, it will cause an excessive increase or decrease in the cross-section of the O-ring, as stretching by 1% correspondingly reduces the cross-sectional diameter W by about 0.5%. For hole sealing, it is best to keep the O-ring in a stretched state, with a maximum allowable stretching amount of 6%; For shaft seals, it is best to compress the O-ring along its circumference, with a maximum allowable circumference compression of 3%.