What should be paid attention to when using O-rings?
Dec 14, 2022
O-rings are widely used in various joints of hydraulic and pneumatic fittings, cylindrical surfaces and flange surfaces. For O-rings used in motion, when the working pressure is greater than 10MPa, if one-way pressure is applied, a retaining ring should be placed on the other side of the O-ring’s pressure direction; Place a retaining ring on each side of the ring.
In order to reduce friction, wedge-shaped retaining rings can also be used. When the pressure liquid acts from the left, the right retaining ring is pushed up, and the left retaining ring is not in contact with the surface to be sealed, so the friction force is reduced.
In general, the use of retaining rings will increase the friction of the sealing device, and the wedge-shaped retaining ring is very important for reducing this friction. For fixed O-rings, when the working pressure is greater than 32MPa, a back-up ring is also required.
When using an O-ring as a reciprocating seal, attention must be paid to the damage caused by the full-tone rolling torsion of the seal and the failure caused by the increase in friction caused by adhesion.
If the O-ring is properly assembled and used under proper conditions, it is generally not easy to roll or twist under reciprocating motion, because the contact area between the O-ring and the sealing groove is larger than the frictional contact area on the sliding surface, and The resistance of the O-ring itself can prevent twisting in the first place.
At the same time, the distribution of friction also tends to keep the O-ring stationary in its groove because static friction is greater than sliding friction, and the seal groove surface is generally not as smooth as the sliding surface.
The service life of the O-ring is directly related to many factors such as service conditions, assembly quality, material of moving parts, machining accuracy, lubrication conditions, and dust-proof measures.
Therefore, the exact service life of the O-ring can only be judged according to the specific working conditions. O-rings for dynamic seals are vulnerable parts. In any application of reciprocating motion seals, they must be used according to the rated data or capacity of the seals, and must be assembled properly so that satisfactory performance can be obtained.
