Mechanical seal composition and definition

Mechanical seal refers to the prevention of fluid leakage caused by at least one pair of end faces perpendicular to the rotation axis under the action of the fluid pressure and the compensating mechanism elastic force (or magnetic force) and the auxiliary seal. Device. The elastic loading mechanism and the auxiliary seal are the mechanical seals of the metallic bellows. We call them metal bellows seals. In the light seal, there is also a rubber bellows for auxiliary sealing. The rubber bellows has limited elastic force, and generally needs to be supplemented with a spring to satisfy the loading elasticity. "Mechanical seals" are often referred to simply as "machine seals."

The basic composition of mechanical seals:

Mechanical seals are oil seals for rotating machinery. Such as centrifugal pumps, centrifuges, reactors and compressors. Since the transmission shaft runs through the inside and outside of the device, there is a circumferential gap between the shaft and the device, and the medium in the device leaks outward through the gap. If the pressure inside the device is lower than atmospheric pressure, the air leaks into the device, so there must be a Block the leaking shaft seal. There are many types of shaft seals. Because mechanical seals have the advantages of less leakage and long life, mechanical seals are the most important shaft seals in these worlds. Mechanical seals, also known as end seals, are defined in the relevant national standards: “The at least one pair of end faces perpendicular to the axis of rotation are held together by the action of the fluid pressure and the compensating mechanism's spring force (or magnetic force) and the auxiliary seal. a device that prevents fluid leakage by sliding relative to each other."

Requirements for the seal ring:

The seal ring is a general term for the moving ring and the stationary ring (the same below), and is the most important component of the mechanical seal. The sealing ring largely determines the performance and life of the mechanical seal, so some requirements are placed on it.

Under working conditions (such as pressure, temperature and sliding speed), the deformation should be as small as possible, and the sealing condition can be maintained when the working conditions fluctuate. In particular, the sealing end face should have sufficient strength and certain corrosion resistance to ensure a satisfactory service life.

For this reason, the material is required to have a high thermal conductivity and a small coefficient of linear expansion, and it is not cracked when subjected to thermal shock.

The seal ring should have a small coefficient of friction.

If short-term dry friction occurs during work, the seal end face is not damaged. Therefore, the sealing ring should have good self-lubricating properties, and the sealing ring material and the sealing fluid should have good wettability.