1. Insufficient machining accuracy
Insufficient machining precision, there are many reasons, some is that the machining precision of the mechanical seal itself is not enough, this reason is easy to attract people's attention and easy to find. But sometimes the machining precision of other parts of the pump is not enough. The reason for this is not easy to attract people's attention. For example: the increase precision of the pump shaft, shaft sleeve, pump body, and sealed cavity is not enough. The existence of these reasons is very detrimental to the sealing effect of the mechanical seal.
2. Vibration is too large
The vibration of the mechanical seal is too large, which will eventually lead to the loss of the sealing effect. However, the reason for the excessive vibration of the mechanical seal is often not the cause of the mechanical seal itself. Other parts of the pump are the source of vibration, such as unreasonable pump shaft design, processing reasons, insufficient bearing accuracy, poor parallelism of the coupling, Reasons such as large radial force.
3. The axial displacement of the pump shaft is large
The sealing surface of the mechanical seal must have a certain specific pressure so that it can play a sealing role. This requires the spring of the mechanical seal to have a certain amount of compression, giving a thrust to the end face of the mechanical seal, and rotating it to make the sealing surface produce the required seal Specific pressure. In order to ensure this specific pressure, the mechanical seal requires the pump shaft not to have too much displacement. The mechanical seal cannot withstand the axial force during use. If the axial force exists, the impact on the mechanical seal is serious. Sometimes due to the unreasonable design of the axial force balance mechanism of the pump and the reasons of manufacturing, installation and use, the axial force is not balanced. The mechanical seal bears an axial force, and the temperature of the sealing gland will be higher during operation. For polypropylene-based media, it will be melted at high temperatures, so the sealing effect will be lost soon after the pump is started, and the sealing end surface will appear when the pump is stationary. Intermittent blowout phenomenon.
4. There is no auxiliary flushing system or the auxiliary flushing system setting is unreasonable
The auxiliary flushing system of the mechanical seal is very important. The auxiliary flushing system of the mechanical seal can effectively protect the sealing surface, cooling, lubricating, and flushing away debris. Sometimes the designer does not configure the auxiliary flushing system reasonably, and the sealing effect cannot be achieved; sometimes although the designer designs the auxiliary system, but due to impurities in the flushing fluid, the flow and pressure of the flushing fluid are not enough, and the design of the flushing port position is unreasonable, etc. , Also can not achieve the sealing effect.
