stirShaft seal of mixing equipmentCommonly used ones includepacking seal、mechanical sealMagnetic seals, etc.

risebeginningThe seals are made of natural materials such as leather and oil soaked ropes as shaft sealsLaterOil immersed rope seal has gradually developed into today's soft packing sealCommon fillers includeAsbestos fabric, carbon fiber, rubber, flexible graphite, and engineering plastics. Due to the development of the petrochemical industry, flammable and explosive substances have strict requirements for sealing performance,Gradually reducing the use of packing seals, as the leakage of packing seals is relatively large, and the frictional resistance is also relatively high, accompanied by problems such as high power consumption and heat generation.From 1935 to 1945, research and application of mechanical seals began in countries such as the United Kingdom and the United States, and developed rapidly.

Mechanical seals have many advantages over packing seals: ① less leakage. The leakage rate of mechanical seals is 1% of that of packing seals. ② The frictional power loss is quite small. Due to the low friction coefficient of the contact surface, the power loss of the mechanical seal is about 10-15% of that of the packing seal. ③ Long service life. Generally, high-quality mechanical seals can be used for 2-5 years and are not required under normal working conditionsespeciallyMaintenance and adjustment. The requirements for the accuracy and smoothness of the shaft are not as strict as those for packing seals, and the vibration resistance is good. When the shaft swings greatly, the mechanical seal can also work well. At the same time, the shaft is not very sensitive to the deviation of the sealing chamber hole, reducing the wear of the shaft or shaft sleeve. When there is an anti-corrosion coating on the shaft (spray, coating, lining, pond, package, etc.), it can overcome the disadvantage of wear or damage to the anti-corrosion layer caused by packing sealing. The disadvantages of machine seals are complex structure, inconvenient assembly and disassembly, high requirements for surface smoothness and flatness of moving and stationary rings, difficulty in processing, and high cost. But compared to its advantages, it only occupies a secondary position. Therefore, the application of mechanical sealsextensive.

When there are extremely hazardous media or flammable and explosive gases (such as hydrogen, carbon monoxide, ethylene, etc.) inside the equipment, various types of dynamic seals may leak. However, using magnetic seals can reduce the risk of leakage to ZUI low, because magnetic seals use the principle of magnetic field lines passing through the isolation cover to transmit torque and successfully convert the dynamic seal at the atmospheric end into a static seal. The leakage risk is equivalent to flange seals, which is the ZUI of magnetic sealsGreat advantages. The disadvantages of magnetic seals are the relatively high cost of magnetic steel, high eddy current heating during high-speed operation, and limited ultimate torque.