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You are here : Mechanical Seal Problems
Also known as seal mechanical seal, which has a rotating axis perpendicular to the face, the face in the fluid pressure and external elastic compensation machinery under the influence of co-dependent on secondary seal to keep fit with the other side, and sliding, to prevent fluid leakage.
First, the common leakage
Mechanical seal leakage ratio of the total maintenance of over 50% of the pump, mechanical seal operation will affect the normal operation, are summarized as follows.
1. Periodic leak
(1) large amount of axial movement of the rotor, the auxiliary shaft seal and the large amount of interference, a flexible ring can not move on the shaft. Flip the pump, dynamic and static ring wear, not compensated displacement.
Solution: In the assembly of mechanical seals, shaft axial movement should be less than 0.1mm, auxiliary shaft seal and the amount of interference should be moderate, while ensuring the radial seal, ring in the shaft after assembly to ensure that mobile and flexible (the ring pressure to spring free to bounce back.)
(2) sealing surface friction caused by lack of lubricant or napping seal faces.
Solution: oil chamber cavity height should be added above the oil dynamic and static ring sealing surface.
(3) periodic rotor vibration. The reason is the stator and the upper and lower end caps or not on the impeller and shaft unbalance, cavitation, or bearing failure (wear), this will shorten the life span and seal the leakage.
Solution: According to maintenance standards to correct the problem.
2. Small submersible sewage pump shaft seal leakage phenomena caused by grinding
(1) 715kW following small mechanical seal failure often produces grinding shaft, grinding axis position are the following: ring secondary seals Department, stationary ring position, the phenomenon of a few springs are grinding axes.
(2) the main axis mill: ¢Ù BIA double mechanical seal, anti-pressure state is bad working condition, medium particles and impurities easily enter the sealing surface of the seal failure. ¢Ú The main pieces of grinding axes for the rubber bellows, and the top sealing surface is due to poor lubrication, the friction torque between the static and dynamic ring rubber bellows is greater than the transmission of torque between the shaft, relative rotation occurs. ¢Û dynamic and static secondary seal ring due to sewage in the weak acid, weak base corrosion, rubber has been inelastic. Some have been decaying, lost its function, resulting in the phenomenon of grinding axes.
(3) to solve the above problems is to take the following measures: ¢Ù to ensure cover in the oil room cleanliness, dirty oil ban on assembly.
Second, due to the leakage of the pressure generated
(1) High-pressure and pressure wave caused by the mechanical seal leakage than the spring pressure than the pressure and the design is too large and seal cavity pressure exceeds 3MPa, makes the seal face pressure ratio is too large, difficult to form film seal face wear serious , the heat increased, rsulting in thermal deformation of the sealing surface.
Solution: In the mechanical seal assembly, the spring according to the provisions of a certain amount of compression, not allowed to have too large or too small, the phenomenon of mechanical seal under high pressure conditions should be taken. In order to face reasonable force, to minimize the distortion, can be hard alloy, ceramics and other materials with high compressive strength, and to strengthen measures to cool the lubricant, the choice of * the transmission mode, such as keys, pins and so on.
(2) run the vacuum caused by the mechanical seal leakage at the start, stop the process, clogging the pump inlet, pumping medium containing gas and other reasons, there may be negative pressure to the sealed chamber, the seal cavity if the negative pressure, can cause seal face friction, will have built-in mechanical seal leakage (water) phenomenon, vacuum seal and pressure seal sealing the object is different from the direction of differences, and mechanical seal has its adaptability to a certain direction.
Strategy: The double mechanical seal, which helps improve the lubrication conditions, and improve sealing performance.
Third, because of media leaks caused by
(1) Most of the dismantling of the submersible sewage pump mechanical seal, the static ring and the auxiliary seal ring inelastic, some of them have decayed, resulting in a large number of mechanical seal leakage and even the phenomenon of grinding axes. Due to high temperatures, water in the weak acid, weak base of the stationary ring and the ring supporting the corrosive effect of rubber seals, causing the mechanical leakage is too large, dynamic and static seal material is nitrile rubber ring -40, not high temperature, no acid, when the water is acidic alkaline corrosive.
Countermeasures: the corrosive medium, the rubber parts should be used in high temperature resistance, weak acid, weak base of fluorine rubber.
(2) solid particles of impurities caused by the mechanical seal leakage if the solid particles into the sealing face will be scratched or speed up the seal face wear
Solution: In the solid particles should be used easily accessible location on the tungsten carbide tungsten carbide mechanical seal friction.
Fourth, because of other problems caused by the mechanical seal mechanical seal leakage, there are still design, selection, installation, and not a reasonable place.
V. Conclusion
Above summarizes the more common mechanical seal leakage causes. Mechanical seal itself is a demanding precision components, design, machining, assembly quality has a very high demand. In the use of mechanical seals, mechanical seal should analyze the various factors used to make all kinds of mechanical seals for pumps required technical requirements and the use of media and there is adequate lubrication conditions, so as to ensure the long-term reliable sealing operation.
First, the common leakage
Mechanical seal leakage ratio of the total maintenance of over 50% of the pump, mechanical seal operation will affect the normal operation, are summarized as follows.
1. Periodic leak
(1) large amount of axial movement of the rotor, the auxiliary shaft seal and the large amount of interference, a flexible ring can not move on the shaft. Flip the pump, dynamic and static ring wear, not compensated displacement.
Solution: In the assembly of mechanical seals, shaft axial movement should be less than 0.1mm, auxiliary shaft seal and the amount of interference should be moderate, while ensuring the radial seal, ring in the shaft after assembly to ensure that mobile and flexible (the ring pressure to spring free to bounce back.)
(2) sealing surface friction caused by lack of lubricant or napping seal faces.
Solution: oil chamber cavity height should be added above the oil dynamic and static ring sealing surface.
(3) periodic rotor vibration. The reason is the stator and the upper and lower end caps or not on the impeller and shaft unbalance, cavitation, or bearing failure (wear), this will shorten the life span and seal the leakage.
Solution: According to maintenance standards to correct the problem.
2. Small submersible sewage pump shaft seal leakage phenomena caused by grinding
(1) 715kW following small mechanical seal failure often produces grinding shaft, grinding axis position are the following: ring secondary seals Department, stationary ring position, the phenomenon of a few springs are grinding axes.
(2) the main axis mill: ¢Ù BIA double mechanical seal, anti-pressure state is bad working condition, medium particles and impurities easily enter the sealing surface of the seal failure. ¢Ú The main pieces of grinding axes for the rubber bellows, and the top sealing surface is due to poor lubrication, the friction torque between the static and dynamic ring rubber bellows is greater than the transmission of torque between the shaft, relative rotation occurs. ¢Û dynamic and static secondary seal ring due to sewage in the weak acid, weak base corrosion, rubber has been inelastic. Some have been decaying, lost its function, resulting in the phenomenon of grinding axes.
(3) to solve the above problems is to take the following measures: ¢Ù to ensure cover in the oil room cleanliness, dirty oil ban on assembly.
Second, due to the leakage of the pressure generated
(1) High-pressure and pressure wave caused by the mechanical seal leakage than the spring pressure than the pressure and the design is too large and seal cavity pressure exceeds 3MPa, makes the seal face pressure ratio is too large, difficult to form film seal face wear serious , the heat increased, rsulting in thermal deformation of the sealing surface.
Solution: In the mechanical seal assembly, the spring according to the provisions of a certain amount of compression, not allowed to have too large or too small, the phenomenon of mechanical seal under high pressure conditions should be taken. In order to face reasonable force, to minimize the distortion, can be hard alloy, ceramics and other materials with high compressive strength, and to strengthen measures to cool the lubricant, the choice of * the transmission mode, such as keys, pins and so on.
(2) run the vacuum caused by the mechanical seal leakage at the start, stop the process, clogging the pump inlet, pumping medium containing gas and other reasons, there may be negative pressure to the sealed chamber, the seal cavity if the negative pressure, can cause seal face friction, will have built-in mechanical seal leakage (water) phenomenon, vacuum seal and pressure seal sealing the object is different from the direction of differences, and mechanical seal has its adaptability to a certain direction.
Strategy: The double mechanical seal, which helps improve the lubrication conditions, and improve sealing performance.
Third, because of media leaks caused by
(1) Most of the dismantling of the submersible sewage pump mechanical seal, the static ring and the auxiliary seal ring inelastic, some of them have decayed, resulting in a large number of mechanical seal leakage and even the phenomenon of grinding axes. Due to high temperatures, water in the weak acid, weak base of the stationary ring and the ring supporting the corrosive effect of rubber seals, causing the mechanical leakage is too large, dynamic and static seal material is nitrile rubber ring -40, not high temperature, no acid, when the water is acidic alkaline corrosive.
Countermeasures: the corrosive medium, the rubber parts should be used in high temperature resistance, weak acid, weak base of fluorine rubber.
(2) solid particles of impurities caused by the mechanical seal leakage if the solid particles into the sealing face will be scratched or speed up the seal face wear
Solution: In the solid particles should be used easily accessible location on the tungsten carbide tungsten carbide mechanical seal friction.
Fourth, because of other problems caused by the mechanical seal mechanical seal leakage, there are still design, selection, installation, and not a reasonable place.
V. Conclusion
Above summarizes the more common mechanical seal leakage causes. Mechanical seal itself is a demanding precision components, design, machining, assembly quality has a very high demand. In the use of mechanical seals, mechanical seal should analyze the various factors used to make all kinds of mechanical seals for pumps required technical requirements and the use of media and there is adequate lubrication conditions, so as to ensure the long-term reliable sealing operation.
