Mechanical seal belongs to one of the precision and structurally complex mechanical basic components, which is critical part of various equipment such as pumps, reaction synthesis kettles, turbo compressors, and submersible motors. The sealing performance and service life of mechanical seals depend on many factors such as selection, precision of the machine, and correct installation and usage. Today, we will talk about the external factors that affect the effectiveness of mechanical seals for water pumps.
There are many reasons for insufficient machining accuracy, some of which are due to the lack of machining accuracy of the mechanical seals for water pumps themselves, which is easy to attract attention and easy to find. But sometimes the machining accuracy of other parts of the pump is not enough, which is not easy to attract attention. For example, the insufficient processing accuracy of pump shafts, shaft sleeves, pump bodies, and sealing chamber bodies. The existence of these reasons is very unfavorable to the sealing effect of mechanical seals for water pumps.
Excessive vibration of mechanical seals ultimately leads to the loss of sealing effectiveness. However, the cause of excessive vibration of mechanical seals is often not the fault of the mechanical seal itself. Other parts of the pump are the source of vibration, such as unreasonable pump shaft design, machining reasons, insufficient bearing accuracy, poor parallelism of the coupler, large radial force, and other reasons.
The sealing surface of mechanical seals must have a certain pressure ratio in order to achieve a sealing effect. This requires the spring of the mechanical seal to have a certain compression amount, providing a pushing force to the end face of the mechanical seal so that it rotates to produce the required pressure ratio. To ensure this pressure ratio, mechanical seals require the pump shaft to not have excessive displacement, and the mechanical seal cannot withstand axial forces during use. If there are axial forces, they can severely affect the mechanical seal. Sometimes, the unreasonable design, manufacture, installation, and use of the axial force balance mechanism of the pump can cause the axial force to not be balanced out. The mechanical seal will experience an axial force, and the sealing cover temperature during operation will be higher, causing polypropylene media to melt at high temperatures. Therefore, the seal effect will be lost shortly after the pump is started, and intermittent leakage will occur at the seal end face while the pump is in a stationary state.
The auxiliary flushing system of mechanical seals is very important. The auxiliary flushing system of mechanical seals can effectively protect the sealing surface, providing cooling, lubrication, and removal of debris. Sometimes the designer does not configure the auxiliary flushing system reasonably, resulting in an ineffectively sealing surface. Sometimes, even if the designer designs the auxiliary system, it may still not achieve the sealing effect due to the presence of impurities in the flushing liquid, insufficient flow or pressure of the flushing liquid, or an unreasonable flushing port position.