What is a mechanical seal? How does a mechanical seal work?1

What is a mechanical seal? How does a mechanical seal work? Mechanical seal (mechanical seal) refers to at least a pair of end faces perpendicular to the axis of rotation, which are formed by maintaining contact and relative sliding under the action of fluid pressure and the elastic force (or magnetic force) of the compensation mechanism and the cooperation of the auxiliary seal. device to prevent fluid leakage. The elastic loading mechanism and auxiliary seal are mechanical seals of metal bellows, which we call metal bellows seals. In light-duty seals, rubber bellows are also used as auxiliary seals. The elasticity of the rubber bellows is limited, and a spring is generally required to meet the loading elasticity. 'Mechanical seal' is often referred to simply as 'mechanical seal'. Mechanical seals are the most important shaft sealing methods in centrifugal pumps, reactors, agitators and other equipment. Mechanical seals, also known as end face seals, are defined in the relevant national standards as follows: 'At least one pair of end faces perpendicular to the axis of rotation is maintained under the action of fluid pressure and the elastic force (or magnetic force) of the compensation mechanism and the cooperation of the auxiliary seal. A device to prevent fluid leakage formed by relative sliding.' A mechanical seal is a shaft seal device of a rotating machine. Such as centrifugal pumps, centrifuges, reactors and compressors and other equipment. Since the transmission shaft runs through the inside and outside of the equipment, there is a circumferential gap between the shaft and the equipment, and the medium in the equipment leaks out through the gap. If the pressure inside the equipment is lower than the atmospheric pressure, the air leaks into the equipment, so there must be a Shaft seal to prevent leakage. There are many types of shaft seals. Because mechanical seals have the advantages of less leakage and long service life, mechanical seals are the most important shaft sealing methods in these equipment in the world. Basic principle of mechanical seal Figure 1 Schematic diagram of single-end waterless mechanical seal , Sealing ring Due to the pressure difference between the fluid in the pump and the atmosphere outside the pump, in order to prevent the leakage of the slurry, the pump needs to be equipped with a sealing device during operation, which is called a shaft seal. Commonly used types of shaft seals are: packing seals, mechanical seals, dynamic seals and floating seals. Judging from the current situation of pumps used in various industries, mechanical seals have become a common sealing form in various industries, and the sealing form operates stably and reliably, bringing great economic benefits to various industries. The mechanical seal is a sealing device composed of two sealing elements (static ring and moving ring) that are perpendicular to the shaft with smooth and flat surfaces and rotate relative to each other, as shown in Figure 1. It relies on the pressure of the elastic member (such as the spring 6) and the sealing medium to generate an appropriate pressing force on the contact surface (end surface) of the rotating moving ring and the static ring, so that the two end surfaces closely fit. A very thin liquid film is maintained between the end faces to achieve the purpose of sealing. This liquid film has hydrodynamic pressure and static pressure. Plays the role of lubrication and sealing. Slurry pumps, desulfurization pumps, agitators and other products can use mechanical seals in different working conditions.