Mechanical seal is the main method of modern pump shaft seal, although it is not easy to use it to achieve no leakage at all, it is possible to achieve a small completely acceptable leakage. However, in the operation of the pump, there are often embarrassing situations, so what are the reasons for the failure of mechanical seal?
1. The material selection of mechanical seal is not appropriate. The material of the mechanical seal does not match the medium delivered. During operation, the sealing elements are quickly corroded, dissolved or worn, thus losing the sealing ability. Therefore, selecting the material of mechanical seal according to the nature of the conveying medium is the prerequisite to ensure its sealing function and normal life.
2. The flushing condition of mechanical seal does not meet the design requirements. When transporting the medium which is easy to crystallize or it has small particles, it must have a certain pressure and a certain flow of flushing liquid to wash, otherwise the crystal or particles will accelerate the wear of the seal pair and affect the automatic compensation of the wear of the seal pair, resulting in leakage. Therefore, according to the nature of the transmission medium, it is not only necessary to configure the corresponding flushing pipeline but also to install instruments and devices with monitoring and regulating functions to ensure that the pressure and flow of the flushing fluid meet the design requirements, so as to maintain the normal operation of the mechanical seal, which is often ignored by the user.
3. There is a limit to the pressure that each mechanical seal can bear. Due to the inaccurate calculation of the pressure in the seal cavity, the pressure in the seal cavity exceeds the pressure that the mechanical seal can bear, resulting in leakage, which is also one of the common reasons for seal failure.
4. The working temperature of the mechanical seal shall not exceed the specified value. In the design of cooling pipeline, the cooling effect is often reduced due to the insufficient flow of cooling medium; in the design of no cooling pipeline, the mechanical seal is often in dry friction state due to the air in the seal cavity. In both cases, the working temperature of the moving seal pair of the mechanical seal will be too high and the wear will be accelerated, resulting in seal failure.
5. Severe wear or damage of the bearing causes serious axial movement of the pump shaft, which is also one of the reasons for leakage of the mechanical seal.
With the development of science and technology, new sealing forms and materials have emerged, which will inevitably have a direct impact on the sealing technology of pumps. Pump products with long life and zero leakage will be popularized and applied in more and more occasion