Rubber O-rings are commonly used in pumps. Due to its simple shape, it is easy to manufacture and cost-effective. No matter how large the overall size of the O-ring is, its cross-sectional size is very small (only a few millimeters), so it is lightweight, consumes less material, has a simple usage method, and is easy to install and disassemble. The more prominent advantage is that the O-ring has good sealing ability and a wide range of applications. The static sealing working pressure can reach over 100MPa, and the dynamic sealing can also reach 30MPa. The applicable temperature is -60~200 ℃, which can meet the requirements of various media. Therefore, it has been increasingly 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 groove bottom surface initial compressive stress. Thus achieving a sealing effect. When the pressure of the sealed liquid increases, the deformation of the O-ring also increases, thereby increasing the pressure transmitted to the sealing surface and enhancing the sealing effect. This is why O-ring seals have good sealing ability.
1. The groove size for installing O-rings exceeds the tolerance, especially when the depth dimension is too large, which results in insufficient compression deformation of the O-rings after installation and affects their sealing ability. Generally, the compression deformation of O-rings after installation should be between 18% and 22%. When the cross-sectional size is large, the relative compression deformation is small, while when the cross-sectional size is small, the relative compression deformation is large.
2. The nominal size of the O-ring seal differs too much from the actual installation size, resulting in insufficient compression deformation and leakage when the O-ring works under reduced cross-sectional size after stretching.
3. During installation, the O-ring may be scratched and leak due to the lack of smooth chamfers 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 fails after being corroded.
5. After being used for too long, O-ring seals age and deteriorate, and their elasticity decreases, leading to failure. Therefore, O-ring seals are usually replaced during equipment maintenance. In addition, the hardness of O-ring seals, as well as the roughness of grooves and sealing surfaces, also affect the sealing effect of O-ring seals.
