Detailed Steps For Replacing Various Mechanical Seals Of Water Pumps

Oct 21, 2024

In order to ensure the normal operation of the water pump, the machine seal is usually replaced once every three months. This article provides detailed instructions on how to replace the machine seal and the steps to replace it, for your reference.
Tools and raw materials:
Adjustable wrench, socket wrench, Phillips screwdriver, Phillips screwdriver, sandpaper, clean cotton cloth, lubricating grease
Repair workbench and a set of brand new machine seals.
Method of mechanical seal for water pump replacement:
1. Install the left part first; Install onto the sealing plate
2. Then install the moving ring on the right, and the sealing surfaces of the moving ring and the stationary ring should be clean
3. Reinstall the flat key and impeller, and attach the gasket and nut.
Before installation, carefully check whether the number of assembled sealing parts is sufficient, whether each component is damaged, especially whether the dynamic and static rings have defects such as collision, cracks, and deformation.
If there is a problem, it needs to be repaired or replaced with new spare parts.
Check if the chamfer of the shaft sleeve or cover is appropriate, and if it does not meet the requirements, it must be repaired.
The components of mechanical seals and their related assembly contact surfaces must be cleaned with acetone or anhydrous alcohol before installation. During the installation process, cleanliness should be maintained, especially for the dynamic and static rings and auxiliary sealing components, which should be free of impurities and dust. Apply a layer of clean engine oil or turbine oil on the surface of the dynamic and static rings.
Tighten the gland after aligning the coupling. The bolts should be tightened evenly to prevent deviation of the cover section. Use a feeler gauge or special tool to check each point, and the error should not exceed 0.05 millimeters.
Check the fit clearance (and concentricity) between the gland and the outer diameter of the shaft or shaft sleeve, ensuring uniformity around. Use a feeler gauge to check that the allowable deviation at each point is not greater than 0.10 millimeters.
The compression amount of the spring should be carried out according to the regulations, and there should be no excessive or insufficient phenomenon. The required error is ± 2.00 millimeters. If it is too large, it will increase the specific pressure of the section and accelerate the wear of the section. Being too small can result in insufficient pressure to seal, so the spring should move flexibly inside the spring seat after installation. When using a single spring, pay attention to the direction of rotation of the spring, which should be opposite to the direction of rotation of the shaft.
After installation, the moving ring must maintain flexible movement and should automatically bounce back when pressed against the spring.
First, place the static ring sealing ring around the back of the static ring, and then insert it into the sealing end cover. Pay attention to protecting the cross-section of the static ring, ensuring the perpendicularity between the cross-section of the static ring and the centerline of the end cap, and align the anti rotation groove on the back of the static ring with the anti rotation pin, but do not let them come into contact with each other.
During the installation process, it is absolutely not allowed to directly strike the sealing components with tools. If it is necessary to strike, special tools must be used to prevent damage to the sealing components
All sealing rings should be coated with lubricants such as soapy water during assembly to avoid damage to the rubber rings during the assembly process. Apply lubricating grease between the sealing surfaces of the dynamic and static rings to prevent them from wearing out before the water pump is started.
When assembling the floating ring, be careful not to knock over the floating ring spring, so as not to affect the floating performance of the floating ring after the spring is knocked over. After assembling the floating ring, you can gently press the floating ring to determine if it has good floating performance.
When installing the seal, it should be handled gently to prevent damage to the seal. The seal and cavity should be cleaned thoroughly during installation.
When tightening the mechanical seal cover, the fastening bolts should be evenly stressed to prevent uneven stress from damaging the mechanical seal. After the overall assembly of the quick installation mechanical seal, do not forget to fix the position of the locating plate radially away from the axis.
Because the medium sealed by mechanical seals is different, the temperature of cold water and hot water is different, whether the sealed medium is corrosive or not, and the pressure inside the chamber are different, the design of mechanical seals will be different, and the maintenance process will also be different,
Some experiences have been summarized during the maintenance process of mechanical seals:
Mechanical seals need to be assembled, and do not forget to clean and inspect them. First look at the two rings, then look at the shaft. Do not leak any scars or cracks.
Finally, when looking at the rubber ring, the diameter of the air hole should be clearly visible. Various dimensions need to be measured, and the gap between the two rings needs to be adjusted properly.
The tension must be checked, and the small spring is the key. The bolt should be evenly stressed and handled with care.
The mechanical seal of a water pump is one of the most effective ways to seal the rotating mechanical body. Its machining accuracy is relatively high, especially for the dynamic and static rings. If the disassembly and assembly method is not appropriate or the use is improper, the assembled mechanical seal will not only fail to achieve the sealing purpose, but also damage the assembled sealing components.
Precautions for disassembling mechanical seals
When dismantling mechanical seals, it is strictly prohibited to use hammers and flat shovels to avoid damaging the sealing components.
If there are mechanical seals at both ends of the pump, caution must be taken during the disassembly process to prevent neglecting one aspect.
For mechanical seals that have been used before, if the sealing surface moves when the cover is loose, the dynamic and static ring parts should be replaced and should not be tightened again to continue use. Because after loosening, the original operating trajectory of the friction pair will change, and the sealing of the contact surface is easily damaged.