Reasons for O-ring Seal Failure
Rubber O-rings are commonly used in pumps. Because of its very simple shape, it is easy to manufacture and low in cost. No matter how big the overall size of the O-ring is, its cross-sectional size is very small (only a few
millimeters), so it is light in weight, consumes less materials, is simple in use, and is easy to install and disassemble. , The more prominent advantage is that the O-ring has a good sealing ability and a wide range of use. The
working pressure of the static seal can reach more than 100MPa, and the dynamic seal can also reach 30Mpa. The applicable temperature is -60 ~ 200 ℃, which can meet the requirements of various media. Therefore, it is
more and more widely used in the design of pumps.
The O-ring is installed between the groove and the sealed surface with a certain amount of compression, and the resulting rebound force gives the sealed smooth surface and the bottom surface of the groove an initial
compressive stress. So as to play a sealing role. When the pressure of the sealed liquid increases, the deformation of the O-ring also increases, so that the pressure transmitted to the sealing surface also increases, and the
sealing effect also increases. This is why O-rings have good sealing ability.
Although the O-ring seal is reliable, if you do not pay attention to the conditions of use, leakage will occur, usually in the following situations:
1. The size of the groove where the O-ring is installed is out of tolerance, especially when the depth is too large, the compression deformation of the O-ring after installation is insufficient and the sealing ability is affected.
Generally, the compression deformation of the O-ring should be between 18% and 22% after installation.
2. The nominal size of the O-ring seal is too different from the actual installation size, and the O-ring is formed to work under the condition that the cross-sectional size is reduced after stretching, resulting in insufficient
compression deformation and leakage.
3. When the O-ring is installed, the O-ring is scratched and leaks due to the lack of smooth chamfering or rounding at the inlet of the sealing surface.
4. The material of the O-ring seal is not suitable for the sealing medium and will fail after being eroded.
5. The O-ring will be aged and deteriorated after being used for too long, and the elasticity will be reduced and then it will fail. Therefore, the O-ring is generally replaced when the equipment is overhauled.
In addition, the hardness of the O-ring, the roughness of the groove and the sealing surface also affect the sealing effect of the O-ring.