One of the main features of mechanical seals is their automatic interface lubrication mechanism that controls sealing function, friction, wear, and lifespan. Everything depends on the liquid that passes through the interface to establish a lubricating film to run under actual no-contact conditions (usually between mixed friction and complete liquid film). Under the action of chamber pressure, the medium passes through the friction pair surface of the seal; surface tension and centrifugal force have little effect at this time. As the fluid flows radially across the end face, the fluid pressure continues to drop until it reaches the external back pressure, which functions similar to fluid static support. The sealing bearing capacity depends on the shape change of the pressure difference and interface gap, and the mathematical analysis is quite complicated. When the seal rotates, the shearing flow inside the end face interacts with the remaining height change of the end face to generate fluid dynamic pressure, which has a bearing function similar to fluid dynamic support and depends on medium viscosity, rotational speed, and end face gap changes.
Under normal conditions, the dynamic pressure field and the static pressure field of the fluid constitute the bearing capacity of the seal during operation, which belongs to the opening force part and is used to prevent rigid contact of the seal. Mechanical seals parts are precision mechanical components, and their correct installation and operation have a significant impact on their service life. So, let's take a look at some precautions to take during installation.
The seal should be placed in a position that closely fits the effective sealing surface (or lip line). After the use of hard-sealed ball valves is opened, further observation and tightening of the seal should be done to prevent system failures that may occur due to changes in working conditions (such as increased pressure) and cause micro-leakage to lead to failure.
Some mechanical seals parts are placed in a grooved packing case. When installing, they need to be tightly matched. The construction process cannot be rough and brutal, and forcibly inserting them will inevitably destroy the original prefabricated structure of the seal. It is like breaking up prefabricated concrete and then filling it into the required parts, which will inevitably lead to disasters. The installation of this type of seal must be very careful and meticulous, and installation should be done step by step.
The flat mechanical seals parts can rely on the upper and lower end faces, and the sealing performance of the hydraulic seal depends on the lip line related to the hole or shaft that is coupled. These parts are made of special materials that are both soft and highly resilient to temperature, corrosion, and aging, such as graphite, rubber, and fibers, which are vulnerable to damage. Therefore, they need special protection and care during handling, installation, and storage. Once damaged, they often leave a significant hidden danger to the sealing area.
When installing mechanical seals parts onto machines, before installation, they should be compared with the overall assembly diagram to confirm whether the parts are complete. Attention should be paid to abnormal phenomena such as scratches, defects, and so on, on the sealing friction pair sealing surface, sealing ring, and surfaces of shafts, bushings, flanges, and other components in contact with packing, O-rings, and other parts. If any abnormal conditions are discovered, the parts must be replaced or repaired before use.