The mechanical seal of the water pump is also one of the key vulnerable parts in the water pump. When selecting the water pump, the material of the mechanical seal must be suitable for the liquid medium transported by the user. Usually, the water pump is equipped with fluororubber mechanical seals when leaving the factory. Some manufacturers use nitrile rubber mechanical seals. If the corrosiveness is severe, PTFE material mechanical seals should be selected.
Steps/Methods
1. The * possibility of water leakage at the mechanical seal of a centrifugal pump is the wear of the dynamic and static ring surfaces of the mechanical seal. There are six reasons for the wear of the dynamic and static ring surfaces of the machine seal: 2. Tight installation. Observe the dynamic and static ring surfaces of the mechanical seal. If there is severe burning, blackening, and deep marks on the surface, the sealing rubber becomes hard and loses elasticity. This phenomenon is caused by too tight installation. Solution: Adjust the installation height. After installing the impeller, use a screwdriver to pull out the spring. The spring has strong tension, and it will reset after release. There should be a movement distance of 2-4MM. 3. The installation is too loose. Observing the sealing and static ring planes, there is a thin layer of scale on the surface that can be wiped off, and the surface is basically free of wear. This is caused by the loss of elasticity of the spring and poor assembly, or by the axial movement of the motor. 4. Poor water quality with particles. Due to poor water quality, the presence of small particles and high content of hydrochloric acid in the medium, abrasive wear can cause flat or scratched surfaces with grooves, ring grooves, and other phenomena. Solution: Improve water pressure or medium, replace machine seal. 5. Dry grinding damage caused by water shortage operation. This phenomenon is more common in the bottom valve installation form where there is negative pressure at the inlet, air in the inlet pipe, and air in the pump chamber. After the pump is turned on, the friction of the mechanical seal generates high temperature during high-speed operation, which cannot be cooled. After checking the mechanical seal, the spring tension is normal, the friction surface is burnt and blackened, and the rubber becomes hard and cracked. Solution: Drain the air from the pipeline and pump chamber, and replace the mechanical seal. 6. Cavitation. Cavitation mainly occurs in hot water pumps. Due to the medium being hot water, steam is generated when the water temperature is too high. The steam in the pipeline enters the high part of the pump chamber, and this part of the steam cannot be eliminated, resulting in water shortage operation, dry grinding failure of the machine seal, cavitation, installation of an automatic exhaust valve, and replacement of the machine seal.
Pump treatment method
1、 The * possibility of water leakage at the mechanical seal is the wear of the dynamic and static ring surfaces of the mechanical seal. There are six reasons for the wear of the dynamic and static ring surfaces of the machine seal: reason one is that the installation is too tight. Observe the dynamic and static ring surfaces of the mechanical seal. If there is severe burning, blackening, and deep marks on the surface, the sealing rubber becomes hard and loses elasticity. This phenomenon is caused by too tight installation. Solution: Adjust the installation height. After installing the impeller, use a screwdriver to pull the spring. The spring has strong tension, and it will reset immediately after release. There should be a movement distance of 24mm. Reason 2: Loose installation. Observing the sealing and static ring planes, there is a thin layer of scale on the surface that can be wiped off, and the surface is basically free of wear. This is caused by the loss of elasticity of the spring and poor assembly, or by the axial movement of the motor. Reason 3: Poor water quality with particles. Due to poor water quality, the presence of small particles and high content of hydrochloric acid in the medium, abrasive wear can cause flat or scratched surfaces with grooves, ring grooves, and other phenomena. Solution: Improve water pressure or medium, replace machine seal. Reason 4: Dry grinding damage caused by water shortage operation. This phenomenon is more common in the bottom valve installation form where there is negative pressure at the inlet, air in the inlet pipe, and air in the pump chamber. After the pump is turned on, the friction of the mechanical seal generates high temperature during high-speed operation, which cannot be cooled. After checking the mechanical seal, the spring tension is normal, the friction surface is burnt and blackened, and the rubber becomes hard and cracked. Solution: Drain the air from the pipeline and pump chamber, and replace the mechanical seal. Reason 5: Cavitation. Cavitation mainly occurs in hot water pumps. Due to the medium being hot water, steam is generated when the water temperature is too high. The steam in the pipeline enters the high part of the pump chamber, and this part of the steam cannot be eliminated, resulting in water shortage operation, dry grinding failure of the machine seal, cavitation, installation of an automatic exhaust valve, and replacement of the machine seal. Reason 6: Assembly issues. When installing the pump cover, it may not be installed flat, resulting in the shaft not being perpendicular to the pump cover and causing the static and dynamic planes to not match. The startup time is not long, causing unilateral wear and water leakage. It is also possible to damage the rubber parts or damage the surface of the dynamic and static rings during installation. Solution: Remove and reinstall, check if the pump cover is installed flat.
2、 The second possibility of water leakage at the mechanical seal is the failure of the mechanical sealant. The reason for the failure of mechanical sealant is the aging and deformation of old rubber parts, mainly in the hot water pump. The phenomenon of mechanical sealant failure is that the water temperature is too high and the medium dissolves the rubber. From the appearance, the surface of rubber parts appears loose and rough, losing elasticity and causing rubber failure. Solution: Replace with a suitable rubber material.
3、 The third possibility of water leakage at the mechanical seal is caused by the static ring chamber of the pump cover. The main reason is that the machining size error of the holes inside the static ring chamber is large, and the surface is rough. The phenomenon manifested is that water is sprayed from the axial direction, there is a gap between the stationary ring and the inner hole, or the inner hole is rough, the stationary ring rotates, and the rubber is worn. Solution: Replace the pump cover. Or wrap the outer ring of the static ring with raw material tape, or add sealing glue for emergency treatment.
4、 The fourth possibility of water leakage at the mechanical seal is poor machining accuracy, small size, roughness, and rusting of the motor shaft neck. The main reason is that the machining size of the motor shaft neck (at the release ring) is small, or due to the corrosive corrosion of the pump shaft caused by the medium, and due to long-term disuse, water is used as the medium, and the electrode potential of the steel shaft and the casting impeller and pump cover is different, forming a primary battery reaction, resulting in shaft neck corrosion. The phenomenon manifested is the surface spots of corrosion. Solution: Polish the corroded surface with sandpaper, wrap it with raw material tape, and place it in a dynamic ring for emergency treatment. The method is to replace the shaft or machine it back to its original size after inserting the shaft sleeve.