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原文：Abstract: the paper analyses the basic principle of mechanical seal, and discusses how to improve the performance of mechanical seals in each link and the matters needing attention, several advanced seal technology are briefly introduced. Key words: mechanical seals, Performance Matters, needing attention, Advanced sealing technology Due to the drive shaft through both inside and outside the equipment, so there is a circumferential clearance between shaft and equipment, equipment of medium leak out through the gap, if the device internal pressure below atmospheric pressure, the air to leak inside equipment, so there must be a stop leaking of shaft seal device. Many different kinds of shaft seal, mechanical seal has the advantages of less leakage and long service life, so is the main shaft seal way in the world today. Mainly through a series of mechanical seal parts axial radial seal can be converted to seal, in the spring and medium pressure, under the function of the equipment operation caused by the axial wear can timely compensation, make the axial seal always stay fit. The sealing performance and service life depends on many factors, such as type selection, the precision of the machine, and before the installation, start-up, operation and shut down after the maintenance operation, etc.1. The selection of Mechanical seal according to the working conditions and the properties of medium, there are high temperature resistant, resistant to low temperature mechanical seal, granular medium resistance of mechanical seal and adapt easy vaporization of light hydrocarbon medium mechanical seal, etc., should choose different according to different use of the structural type and materials of mechanical seal. In the installation and use to select according to the requirement of the mechanical seal the precision of the machine, according to the axis of rotation always choose spring left and right hand.2. InstallInstallation method according to the mechanical seal type and the type of machine is different, but the installation essentials are almost the same, the installation steps and matters needing attention are as follows: 2.1 installation of right determine size. 2.2 prior to loading, axial (collar), gland should be no burr, bearing in good condition; Seal, shaft, sealing cavity, gland should be cleaned. In order to reduce frictional resistance, and shaft installed on mechanical seal parts to thin coated with oil, for lubrication, considering the intermiscibility of rubber o-ring, if not oil, can besmear soap and water. Without a stop pin float mounted static ring structure, not oil, should be dry load a gland. 2.3 to static ring mounted on the shaft with gland, be careful not to into the shaft, then load ring components. Spring bridge or transmission of evenly tighten the set screws should be several times. 3. Before the start of the preparation work and the matters needing attention 3.1 overall check mechanical seal, mechanical seal before the start of hydrostatic test, check whether there is leakage phenomenon. 3.2 before the start of sealed cavity filled with liquid shall be maintained. For solidification of the medium, the application of steam seal chamber heating melt medium according to the pump rotate to turning, check whether the light evenly. Such as turning demanding or not move, should check whether assembly size error, installation is reasonable. 4. The running maintenance 4.1 when the temperature of the medium to high, low, or containing impurity particles, inflammable, explosive, toxic, must adopt corresponding resistance sealing and flushing, cooling, filtering and other measures. 4.2 before turning by hand operation, pay attention to whether the torque is too big, any scratch and abnormal sound. 4.3 turn to pay attention to, and whether the coupling of, the bearing parts of the lubricating oil additive is appropriate, piping is correct. 4.4 before the first operation will be medium, the cooling water valve is open, check the gas in the sealed cavity is completely discharge, to prevent leaks by static pres4.5 is normal after driving stability, have without shaft turning caused by abnormal torque, as well as the abnormal noise and overheating. 5. Stop 5.1 with WaiFeng oil pump system of mechanical seal, should start the seal oil system. Stop after the last stop in sealing system. 5.2 hot oil pump shut down not immediately stop after the oil seal cavity and end face seal cooling water, should be end face seal oil temperature has dropped below 80 degrees, can stop the cooling water, so as not to damage sealing parts .6. New technological upgrading In order to improve the reliability and life of the mechanical seal, reduce wear and tear, the adoption of new materials and new technology of all kinds of mechanical seal technology. Has the advanced mechanical seals used technology mainly have the seals to shape, control balance ratio sealing technology, combined sealing technology and controllable mechanical seal technology, etc., can change the mechanical seal performance. Here mainly introduce the seals fractal technology. Seal face to fractal technology is through the various forms of trough on seal face to improve the face lubrication conditions, so as to realize the long life of mechanical seal, it is a high and new technology in the field of mechanical seal today. 6.1 a dry gas seal technologyDry gas seal is a slotted sealing technology used in gas sealing, belongs to the non-contact seal. On the outside of a sealing ring end face of dry gas seal processing has a uniform distribution of dynamic pressure groove of 2.5-10 um, as east ring rotates, fluid dynamic pressure groove to the outside of the high voltage isolation between gases pumped into the seals, gas film from the outside diameter to the groove root pressure increase gradually, and the groove root of air film pressure gradually decreases from the inner diameter, because the face film formed by the pressure increase del open force is greater than the effect on the sealing ring closing force, between friction pair in the formation of a thin layer of gas film, so that the rice noodles work in non contact mode, the formation of the gas film completely blocked the relatively low pressure sealing medium leakage channel, to achieve zero leakage of sealing medium. The sealing run without wear and tear, low consumption; Leak quantity is small, which can realize zero leakage; Structure is relatively simple, no complicated oil seal system, the low cost of installation and maintenance; System is reliable, which can realize stable operation for a long period of time. Trough the main points of dry gas seal face of single screw and twin twist to the two classes. Single screw to the trough can be used only in unidirectional rotating rotating equipment, in spin down before the requirements can produce open, such as inversion produces negative and may cause the damage of seal opening force. But relative to the twin twist to the channel, it can form a bigger opening force and film stiffness, higher stability and more reliable protection against contact face. Reason under the low speed and large vibration can also be used, in the present is the most used. A two-way channel to require irrotational, positive &negative all can use. The reversal of the rotor will not result in damage to seal. The use scope is single screw to the groove width, but its stability, anti-interference ability is ChanXiangXuan to the poor. 6.2 the upstream pumping seal Working principle of upstream pumping seal and dry gas seal, is by opening the seal ring cross section inside the fluid dynamic pressure groove under the condition of the rotation of the viscous shearing action between pumping the liquid seal face, make the liquid film pressure increases and separate the two seal face; Differs, dry gas seal and upstream pumping seal end of fluid dynamic pressure groove reveal your is composed of high voltage side to low voltage side of the sealed fluid to lose ambition high side, in order to eliminate the sealing medium is composed of high voltage side to low voltage side of the leak. 6.3 face deep groove type hydrostatic mechanical seal Face deep groove type hydrostatic mechanical seal is on the seal face a few group of groove depth of a few millimeters or holes and pressure medium into the hole, the seal fluid or external lubrication fluid is introduced into the seals, and thus sufficient lubrication and cooling of the seals. In structure with the pressure groove and pressure groove outside, etc. Since the pressure groove type several small opening in the non-rotating peripheral and and end face of the ring grooves are interlinked, thus introducing the pressure of seal medium sealing end surface; Outside pressure groove type of rotating ring circumferential outer holes and sealing medium are interlinked, and lubrication fluid source communicates with the outside world, introducing the fluid seals for lubrication and cooling. Face deep groove type hydrostatic mechanical seal, because of the pressure medium is face, balance the closing force, so that two separate become a non-contact type mechanical seal, despite leakage is larger, general hundred milliliters per hour, far more than the conventional mechanical seal leakage, but it is still widely used in ordinary mechanical seal of high pressure, high speed and high temperature, working condition is difficult to do it. In order to reveal the mechanical seal related laws, improve the reliability of parameters of mechanical seal face test and research is the key. Special properties of nanomaterials is helpful to improve the lubrication condition between the mechanical seal face, development of nano-materials mechanical seal mechanical seal research and application of nano rinses will be short-term goals. With the improvement of the experience and the development of technology, mechanical seal will be more and more mature, step by step towards zero leakage, long-term stable operation.