The o-ring is an extruded seal. The basic working principle of the extruded seal is that the elastic deformation of the seal parts causes contact pressure on the sealing contact surface, and the contact pressure is greater than the internal pressure of the sealed medium, there is no leakage, on the contrary, there is leakage.

O-rings are flexible and stretchable，O-type sealing ring is a typical extrusion-type seal. The compression ratio and drawing capacity of O-ring section diameter are the main contents of sealing design, which are of great significance to sealing performance and service life. The good sealing effect of o-ring depends on the size of o-ring to a large extent, and the groove size of the correct match to form a reasonable sealing ring compression and tension.