Common Knowledge Of U-ring

U-shaped seal ring is a kind of reciprocating seal, with a U-shaped section, which is called U-shaped seal ring for short. There are two types of U-shaped seal rings, rubber type and cloth clip type. The U-shaped seal made of PTFE as the base material and added with packing can be installed on the moving piston or as a fixed seal on the housing for sealing without adjusting the packing gland.

Advantages of U-shaped seal ring: the single lip type has no effect on heavy load and piston rod bending. Compared with the double lip type, the friction force is small in the low pressure range. The double lip type has good corrosion resistance and wear resistance. It forms a good lubricating oil film in the seal clearance and has no effect on sudden load.

The U-shaped seal is a balanced seal, that is, it is sealed on both the inner and outer diameters, and is equipped with a backup ring to protect the seal from being flattened or distorted under pressure. The U-ring is installed in the sealing groove, and the clearance between the pressure ring and the lip is 1.6~3mm, that is, at least 25% of the lip thickness, so that the lip cannot contact the pressure ring, so that the system fluid can enter freely, so that the self tightening principle can be used for sealing. The transverse hole on the vertical web of the compression ring can ensure the pressure balance in the U-shaped opening. A rubber O-ring is used to increase the static and dynamic contact force to improve the initial sealing effect.