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Comparison between mechanical seals and packing seals: A mechanical seal has three sealing points, and the sealing principles for these points are as follows: 1. Sealing between the rotating ring and the stationary ring: This is achieved through elastic components (such as springs, bellows, etc.) and the pressure of the sealing fluid, which generate an appropriate compressive force (specific pressure) on the contact surface (end face) of the rotating and stationary rings in relative motion, thereby ensuring that the two smooth, flat end faces fit tightly together； A very thin layer of liquid film is maintained between the end faces to achieve sealing. This film possesses dynamic and static pressures; it serves to balance the pressures and lubricate the end faces. The end faces must be extremely smooth and flat in order to ensure a perfect fit between them and to achieve uniform pressure distribution, which is characteristic of relative rotational sealing. 2. Sealing between the stationary ring and the gland: Elastic auxiliary sealing rings of various shapes (such as rubber) are used to prevent liquid from leaking between the stationary ring and the gland; this constitutes a static seal. 3. Sealing between the rotating ring and the shaft: Various elastic auxiliary sealing rings of different shapes are also used to prevent liquid from leaking between the rotating ring and the shaft. This is a relatively stationary seal. However, when the end face is worn, axial movement is allowed to compensate for the wear. Comparison between mechanical seals and stuffing box seals: I. The seals are reliable, with little to no leakage over a long period of use. Clean, with no dead corners, preventing contamination by unwanted bacteria. II. Long service life: A mechanically sealed system with the friction load specific pressure selected properly can be used for 2 to 5 years, and in some cases up to 9 years. III. It has a long maintenance cycle; no maintenance is required under normal operating conditions. IV. The shaft or bushing is not worn. V. Frictional power loss is low, generally ranging from 10% to 50% of that in a stuffing box seal. VI. Mechanical seals do not require such high precision and smoothness of the shaft as stuffing box seals; they are less sensitive to the vibration of the rotating shaft and to any deviation of the shaft relative to the holes in the housing, and they are also less sensitive to shaft vibrations. VII. It has a wide range of applications, and can be used for sealing in low-temperature, high-temperature, high-vacuum, high-pressure conditions, as well as in the presence of corrosive, abrasive, flammable, explosive, or toxic media, at various rotational speeds. Working principle of mechanical seal: A mechanical seal, also known as an end-face seal, is a dynamic seal for rotating shafts. Mechanical seals offer reliable performance, low leakage, a long service life, and low power consumption. It requires no frequent maintenance, and can adapt to automated production processes as well as high temperatures, low temperatures, high pressures, vacuum conditions, high speeds, and various highly corrosive media. Sealing requirements for harsh operating conditions such as media containing solid particles. A mechanical seal is a shaft sealing device that prevents leakage by relying on a pair or several pairs of end faces that move relative to each other perpendicular to the axis; these end faces remain in contact under the action of fluid pressure and the elastic force (or magnetic force) of a compensation mechanism, along with the help of additional sealing elements. Requirements of gear oil pumps for mechanical seals; a comparison between mechanical seals and soft packing seals is as follows: Advantages: 1) Reliable sealing – the sealing performance remains stable over long periods of operation, with very low leakage levels; the leakage is approximately 1% of that in soft packing seals. 2) Long service life – in oil or water environments, they can typically last 1–2 years or even longer. It generally operates in chemical media for more than half a year: 3) Low friction power consumption, with the frictional power being only 10%~50% of that of soft packing seals; 4) The shaft or shaft sleeve suffers little wear; 5) Long maintenance intervals. It can automatically compensate for end-face wear, and regular maintenance is generally not required: 6) It has good seismic resistance and is insensitive to vibrations of the rotating shaft as well as to any deviation of the shaft relative to the sealing chamber: 7) It has a wide range of applications; mechanical seals can be used in high-temperature, low-temperature, high-pressure, vacuum environments, as well as in situations with different rotation frequencies, and they can also be used to seal against various corrosive media and media containing abrasive particles. Disadvantages: 1) It is relatively complex and requires high standards for processing. 2) Installation and replacement are cumbersome, requiring workers to have certain technical skills. 3) It is difficult to handle in the event of accidental accidents. Preparations before sealing at high pressure: 1) Check the model of the mechanical seal. Check whether the specifications meet the requirements of the design drawings, and thus whether there is any damage to the parts (especially the sealing surfaces and auxiliary seals). Deformation. For phenomena such as cracks, if any defects are present, they must be replaced or repaired. 2) Check whether the fit dimensions, roughness, and parallelism of all the components of the mechanical seal meet the design requirements. 3) When using a small-spring mechanical seal, verify that the length and stiffness of the small springs are identical. 4) Check the amount of movement of the main unit. It is necessary to check whether the amount of swing and deflection meet the technical requirements, whether the sealing chamber conforms to the installation dimensions, and whether the sealing end cover is perpendicular to the shaft. The general requirements are as follows: the axial movement of the shaft should not exceed ±0.5 mm; the swing of the shaft (at the location of the rotating ring seal) should not exceed 0.06 mm; the maximum deflection of the shaft should not exceed 0.05 mm. The allowable deviation in the perpendicularity between the contact surface of the sealing end cover and the gasket and the centerline is 0.03–0.05 mm. 5) The area in question must be kept clean, especially the sealing surfaces of the rotating ring and the stationary ring, as well as the surfaces of the auxiliary seals, which must be free from any impurities. Dust. It is not allowed to wipe the sealing surface with unclean materials. 6) It is not allowed to strike the sealing element with tools. to prevent the seal from being damaged