How much do you really know about pump sealing
1. Chemical pump packing seal is the process of placing highly compressible and resilient packing into the packing box, which relies on the axial compression force of the gland to convert it into radial sealing force, thereby achieving a sealing effect. This sealing method is called packing sealing, and this packing is called sealing packing. Due to its simple structure, easy replacement, low cost, adaptability to speed, pressure, and wide range of media, packing sealing is widely used in the design of chemical pumps.
2. What is the packing seal for chemical pumps?
Chemical pump packing seal is the process of placing highly compressible and resilient packing into the packing box, which relies on the axial compression force of the gland to convert it into radial sealing force, thereby achieving a sealing effect. This sealing method is called packing sealing, and this packing is called sealing packing. Due to its simple structure, easy replacement, low cost, adaptability to speed, pressure, and wide range of media, packing sealing is widely used in the design of chemical pumps.
Regarding the sealing of the pump
1. The water, grease, oil, and other neutral liquids used for this purpose are called "sealing liquids". The sealing principle of sealing fluid can be explained by the basic concepts of fluid mechanics. The concept of using sealing liquid also indicates that the sealing liquid must leak outward to a greater or lesser extent from the direction of the sealing length, as the energy of the sealing liquid itself is higher than that of the medium at both ends along the sealing length, preventing the different media at both ends from being outside the entire sealing length. Here, sealing is for the working medium, and leakage is for the sealing fluid. Sealing fluid cannot have harmful effects on the working medium. Obviously, the sealing fluid still acts as a lubricant throughout the entire sealing length. In this device, the position of the lubrication ring has great significance. If the lubrication ring is arranged near the bottom of the packing box, the resistance flowing to the sealing device is greater than the resistance in the opposite direction, so the sealing fluid flows in the opposite direction of the device.
What is the sealing function of a pump? How many types are there?
1. Centrifugal pumps are sealed with external seals. The leakage of vertical centrifugal pumps occurs at the sealing position. Mechanical seals and packing seals are common seals for shielded pipeline centrifugal pumps. The function of the fluoroplastic lined centrifugal pump shaft seal device: a certain gap is required between the rotor and the pump casing, and a sealing device is installed at the part where the pump shaft extends out of the pump casing.
What are the forms of pump sealing
1. The main sealing forms of centrifugal pump shaft end include packing seal, mechanical seal, floating ring seal, and labyrinth seal. Packing seal is composed of packing gland, packing, water seal ring, packing box, etc. It is currently the most commonly used shaft seal for ordinary centrifugal pumps. When the centrifugal pump is working, the gland compresses the packing tightly, reducing the leakage and achieving the purpose of sealing.
What is the function of the sealing fluid in the pump
The function of pump sealing water is to:
The high-pressure water in the feed pump, although passing through the sealing element, still has a certain pressure. In order to prevent the water in the feed pump from leaking out through the gap between the shaft and the sealing element, a water source is introduced from the outlet of the condensate pump or the desalinated water main pipe as sealing water!
Where is the sealed chamber of the pump
Sealing chamber pressure: ≤ 5Mpa when the corrugated pipe is subjected to external pressure, ≤ 5Mpa when the corrugated pipe is subjected to internal pressure. Sealing chamber temperature: 20 ℃~400 ℃. Linear velocity: ≤ 15m/s. HBM5 type mechanical seal is a single end, balanced, rotating metal corrugated pipe mechanical seal. The dynamic ring part is connected to the shaft sleeve as a whole, and the whole set of mechanical seals is containerized, simplifying the installation process. The pump is adjusted externally, making the installation of mechanical seals simpler.
The principle of pump sealing
1. The core principle of mechanical seal is to use the reasonable combination of dynamic and static rings to achieve the sealing effect on the pump. Can pump seals remove leaks?
The problem of sealing in general pumps is concentrated on the pressure difference inside and outside the body, which cannot be eliminated.
However, sealing does not completely remove leaks, but rather controls them within an acceptable range for everyone. The national standard for leakage of ordinary mechanical seals is 35ml/h, which is relatively easy to achieve.
2. The static sealing mechanism is relatively simple. The sealing interface of the oil seal is a narrow ring with a width of 0102mm. Under the action of preloading (usually a spring), there is generally an average radial contact pressure of about 1N/mm2 between the oil seal and the shaft; When the lubricating oil pressure is lower than this pressure value, the oil seal prevents it from leaking to the outside.
However, static non leaking oil seals may still leak during operation. During normal operation, oil first enters the narrow band of contact between the oil seal and the shaft through capillary action and the pumping action of rough tissue (the roughness of the narrow band of the oil seal and the shaft).
When entering this contact surface, the pumping effect begins to take effect.
The cascade micro pump on the atmospheric side has a high potential pumping capacity, which forms fluid dynamic pressure equilibrium on this basis. Now, the seal operates on the oil film to maintain a sealed state, and the operating state at this time is a lean lubrication state. This is the microscopic model of the oil seal sealing mechanism.
3. Mechanical seal
4. Water pump seals generally use mechanical seals. The principle is that mechanical seals are devices that prevent fluid leakage by keeping at least one pair of end faces perpendicular to the axis of rotation in contact and sliding relative to each other under the action of fluid pressure and compensation mechanism elasticity (or magnetic force), as well as the cooperation of auxiliary seals. Mechanical seal belongs to a type of seal, generally used for dynamic sealing of rotating parts. By cooperating with appropriate flushing schemes, it can achieve trace or zero leakage of the medium (sealing gas/liquid will enter the medium).
Common sealing methods for pumps
1. Packing seals can be divided into soft packing seals, hard packing seals, and molded packing seals according to their structural characteristics. The packing is usually woven from relatively soft linear materials, filled into the sealing chamber with square shaped strips, and pressed by the cover to produce a compressive force, forcing the packing to press against the sealing surface (the outer surface of the shaft and the sealing chamber), producing a radial force for sealing effect, thus playing a sealing role. The manufacturing material selected for the packing of the packing determines the sealing effect of the packing. Generally speaking, the manufacturing material of the packing is limited by the temperature, pressure, and acidity of the working medium. In addition, the surface roughness, eccentricity, and linear velocity of the mechanical equipment that the packing works on also have requirements for the material selection of the packing. Graphite packing is capable of withstanding high temperatures and pressures, and is one of the most effective products for solving sealing problems under high temperatures and pressures.
2. Oil seal is a self tightening lip seal with a simple structure, small size, low cost, easy maintenance, and small resistance torque. It can prevent medium leakage, external dust and other harmful substances from entering, and has a certain compensation ability for wear. However, it is not resistant to high pressure and is generally used in chemical pumps in low-pressure applications. During the operation of the chemical pump, the pressure head generated by the secondary impeller balances the high-pressure liquid at the outlet of the main impeller, thereby achieving sealing.
3. Dry gas seal, as a maintenance free sealing system that does not require any sealing end face cooling or lubricating oil, is replacing floating ring seal and labyrinth seal as the main seal for high-speed centrifugal compressor shaft seals in the petrochemical industry.
Centrifugal compressors and other high-speed fluid machinery are suitable for working conditions where a small amount of process gas leaks into the atmosphere without harm, such as air compressors, nitrogen compressors, etc. Maze seal is a series of annular sealing teeth arranged in sequence around the rotating shaft, forming a series of interception gaps and expansion cavities between the teeth. The sealed medium produces throttling effect when passing through the gaps of the tortuous maze to achieve the purpose of preventing leakage. Maze seal is the most basic sealing form between stages and shaft ends of centrifugal compressors. According to different structural characteristics, it can be divided into four types: smooth, tortuous, stepped, and honeycomb.
4. What are the characteristics of packing seals?
Packing seals can be divided into soft packing seals, hard packing seals, and molded packing seals according to their structural characteristics. The packing is usually woven from relatively soft linear materials, filled into the sealing chamber with square shaped strips, and pressed by the cover to produce a compressive force, forcing the packing to press against the sealing surface (the outer surface of the shaft and the sealing chamber), producing a radial force for sealing effect, thus playing a sealing role. The manufacturing material selected for the packing of the packing determines the sealing effect of the packing. Generally speaking, the manufacturing material of the packing is limited by the temperature, pressure, and acidity of the working medium. In addition, the surface roughness, eccentricity, and linear velocity of the mechanical equipment that the packing works on also have requirements for the material selection of the packing. Graphite packing is capable of withstanding high temperatures and pressures, and is one of the most effective products for solving sealing problems under high temperatures and pressures.
5. What is sealing fluid?
The water, grease, oil, and other neutral liquids used for this purpose are called "sealing liquids". The sealing principle of sealing fluid can be explained by the basic concepts of fluid mechanics. The concept of using sealing liquid also indicates that the sealing liquid must leak outward to a greater or lesser extent from the direction of the sealing length, as the energy of the sealing liquid itself is higher than that of the medium at both ends along the sealing length, preventing the different media at both ends from being outside the entire sealing length. Here, sealing is for the working medium, and leakage is for the sealing fluid. Sealing fluid cannot have harmful effects on the working medium.
Obviously, the sealing fluid still acts as a lubricant throughout the entire sealing length. In this device, the position of the lubrication ring has great significance. If the lubrication ring is arranged near the bottom of the packing box, the resistance flowing to the sealing device is greater than the resistance in the opposite direction, so the sealing fluid flows in the opposite direction of the device.
