Disassembly and assembly method of centrifugal pump mechanical seal
Disassembly and assembly method of mechanical seal; disassembly and assembly of mechanical seal; mechanical seal
Mechanical seal is one of the most effective ways to seal the mechanical body. The precision of its own machining is relatively high, especially the dynamic and static rings. If the disassembly method is not suitable or used improperly, the mechanical seal after assembly will not reach the seal. Purpose, and will damage the assembled sealing elements.
1. Precautions for mechanical seal removal
When removing the mechanical seal, it is strictly forbidden to use the hand hammer and the flat shovel to avoid damage to the sealing components.
If there is a mechanical seal at both ends of the pump, care must be taken during the disassembly process to prevent this from happening.
For mechanical seals that have been worked, if the sealing surface moves when the gland is loose, the moving ring parts should be replaced and should not be re-tensioned for continued use. Because the original running track of the friction pair changes after loosening, the sealing of the contact surface is easily destroyed.
If the sealing element is bonded by dirt or condensate, the condensate should be removed before the mechanical seal is removed.
2. Precautions for mechanical seal installation
Before installation, carefully check whether the number of assembled sealing parts is sufficient, whether the components are damaged, especially the dynamic and static rings, such as bumps, cracks and deformation. If there is a problem, repair or replace it with a new one.
Check that the chamfering of the bushing or gland is appropriate and that it must be trimmed if it does not meet the requirements.
The mechanical seal components and their associated assembly contact surfaces must be cleaned with acetone or absolute alcohol prior to installation. It should be kept clean during the installation process, especially the moving and static rings and auxiliary sealing components should be free of impurities and dust. Apply a layer of clean engine oil or turbine oil to the surface of the moving and stationary rings.
Tightening the gland should be done after the coupling is aligned. The bolts should be evenly tightened to prevent the gland section from being skewed. Check the points with a feeler gauge or special tools with an error of no more than 0.05 mm.
Check the fit clearance (and concentricity) between the gland and the outer diameter of the shaft or bushing. It must be uniform around the circumference. Check the tolerance of each point with a feeler gauge of no more than 0.10 mm.
The amount of spring compression should be carried out according to the regulations. It is not allowed to be too large or too small. The required error is ±2.00 mm. The sectional specific pressure is increased and the section wear is accelerated. If it is too small, it will cause insufficient sealing pressure and will not seal. After the spring is installed, it should be flexible in the spring seat. When using a single spring, pay attention to the direction of rotation of the spring. The direction of rotation of the spring should be opposite to the direction of rotation of the shaft.
After the moving ring is installed, it must be kept flexible. When the moving ring is pressed against the spring, it should be able to bounce back automatically.
The static ring seal is placed on the back of the static ring and then placed in the sealed end cap. Pay attention to protect the static ring section, ensure the perpendicularity of the static ring section and the center line of the end cover, and align the anti-rotation groove on the back of the static ring with the anti-rotation pin, but do not make them contact each other.
Never use tools to directly hit the sealing components during the installation process. When knocking, special tools must be used to strike to prevent damage to the sealing components. All sealing rings should be coated with lubricant such as soapy water during assembly. This avoids assembly. Damage to the apron. Grease is applied between the sealing surfaces of the static and dynamic rings to prevent the static and dynamic ring sealing surfaces from being worn before the pump starts driving.
When assembling the floating ring, be careful not to knock down the floating ring spring to avoid the floating performance of the floating ring after the spring hits. Once the floating ring is assembled, you can gently press the floating ring to determine if there is good floating performance.
When installing the seal, it should be handled gently to prevent damage to the seal. The seal and the cavity should be cleaned during installation.
When tightening the mechanical seal gland, tighten the bolts evenly to prevent the mechanical seal from being damaged by uneven force. For the quick-fit mechanical seal, after the assembly is completed, do not forget to fix the position of the radial movement of the positioning piece away from the shaft.
Because the medium sealed by the mechanical seal is different, the temperature of the cold water and hot water is different, the sealed medium is corrosive, the pressure inside the chamber is different, the design of the mechanical seal will be different, and the maintenance process will be different.
Some experience was learned during the mechanical seal inspection process: the mechanical seal should be assembled, and the cleaning inspection should be forgotten. Look at the shaft after looking at the two rings first. Do not leak the cracks. Finally, look at the rubber ring, the diameter of the pores should be clear. Various sizes need to be measured, and the gap between the two rings should be adjusted. Tightness must be checked, and small springs are the key. The bolts should be evenly stressed, and it is easy to take care of them.
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