Magnetic fluid fan seal is a relatively new sealing method. Compared with previous mechanical seals, labyrinth seals, bearing seals, etc., it has more no leakage, better sealing, and basically has no leakage.
The main purpose of sealing is to protect the working medium and prevent leakage or pollution of the working medium. With the rapid development of the industry, sealing is playing an increasingly important role in the field of industrial equipment and machinery manufacturing. Poor sealing will cause leakage of the sealing medium and pollute the environment. At the same time, external impurities invade the equipment and contaminate the sealed medium, which seriously affects the normal operation of the production, causing huge production waste and economic losses. Static seal and dynamic seal are two basic forms of seal. Static seal refers to the seal between relatively stationary parts in mechanical equipment, and dynamic seal refers to the seal between relatively moving parts. At present, the traditional sealing method mainly uses rubber seals. Rubber components include nitrile rubber, hydrogenated nitrile rubber, silicone rubber, fluorine rubber, etc. Rubber seals are widely used and are currently the most widely used one. There are many shortcomings such as easy expansion and dissolution, easy wearing by seals, easy to contaminate the sealing medium, and easy aging, etc. Rubber parts are easy to cause poor sealing performance, which will cause the sealing equipment to lose its sealing performance.
Compared with the traditional sealing defects, magnetic fluid sealing uses magnetic force to seal, which has the superiority of traditional sealing. Its main characteristics are as follows:
(1) Leak-free sealing: magnetic fluid is a fluid with high saturation magnetic strength. At present, high-saturation magnetic strength magnetic fluid and well-designed sealing devices can be used to perform tight and highly stable dynamic or static sealing of the medium, and Hardly leaked. The reason is that the magnetic fluid can fill the sealing gap of the entire sealing equipment to form a "liquid O-ring seal". At the same time, the magnetic field strength of the sealing device is changed, and the viscosity of the magnetic fluid will change accordingly, which can strengthen the magnetic fluid sealing effect and further reduce The possibility of leakage of the sealing medium is reduced. This characteristic is very important for sealing corrosive gases as well as toxic, flammable and explosive gases.
(2) Non-wearing seal: Due to the large friction and wear between the contact elements, the traditional contact seal affects the service life of the seal on the one hand, and affects the power of the mechanical equipment on the other, resulting in large power loss of the mechanical equipment. The magnetic fluid seal avoids the debris caused by the friction between the seal and the rotating shaft. At the same time, the magnetic fluid as an oil-based fluid also has a lubricating effect, which plays an important role in protecting mechanical equipment parts and reducing friction and wear.
(3) Non-pollution seal: Because the magnetic fluid seal uses liquid magnetic fluid as the sealing element, there is no friction and wear itself, and no grinding occurs. At the same time, the magnetic fluid has extremely low saturated vapor pressure, which can ensure It will not cause pollution to the sealing medium, and the magnetic fluid seal can effectively avoid external and internal pollution to the sealing medium.
(4) Non-directional sealing: The design of the magnetic fluid sealing device allows both sides to withstand different pressures. If the pressure direction of the sealing device needs to be changed, it can be achieved without adding any components to the magnetic fluid. The magnetic fluid sealing has no directionality , The prevention of external leakage is as effective as internal leakage.
(5) Lossless sealing: magnetic fluid generally uses oily liquid substances as the base liquid. In the seals equipped with bearings, the magnetic fluid itself has very little internal frictional force in the rotating state, and the heat generation is low, which greatly reduces Because the friction of the seal causes the loss of mechanical power, the power loss of the magnetic fluid seal is small, so it can also be used for high-speed rotary seals.
(6) Long-life seal: As a special seal, the life of magnetic fluid seal is mainly determined by the life of the magnetic fluid. The magnetic fluid itself is a stable fluid, and its effective life can reach 20 years at 40 ° C. Keep the magnetic fluid characteristics unchanged. In addition, the magnetic fluid seal structure is simple in construction system and reliable in working performance.
(7) Stability seal: Because magnetic fluid has both fluid effect and viscosity change effect under the action of magnetic field, magnetic fluid seal will not cause loss of sealing performance due to transient over-pressure breakdown. In the process of use, even If the sealing device fails due to magnetic fluid, it only needs to be replaced or replenished.