In industrial production, mechanical seals, as key components of equipment, their performance directly affects the safe operation and efficiency of the equipment. However, the problem of mechanical seal leakage occurs from time to time, which not only increases maintenance costs but also may cause pollution to the production environment. So, what exactly are the reasons for the leakage of mechanical seals? This article will provide you with a detailed analysis.
I. Basic Structure of Mechanical Seals
Mechanical seals are mainly composed of a moving ring, a stationary ring, a spring, a sealing ring and other components. Through the close contact between the moving ring and the stationary ring, a seal is achieved between the rotating part and the stationary part. This sealing method has the advantages of low leakage and long service life, and is widely used in rotating equipment such as pumps and compressors.
Ii. Main Causes of leakage in Mechanical Seals
Wear on the planes of the moving and stationary rings
Excessive installation: When installing a mechanical seal, if the moving and stationary ring planes are subjected to excessive pressure, it will cause severe wear on the planes, and even lead to charring, blackening, and loss of sealing effect.
Loose installation: On the contrary, if the installation is too loose, the dynamic and static rings cannot form a tight fit, which will also lead to water leakage.
Poor water quality with particles: Small particles or high-concentration salt carbonate and other impurities contained in the medium will accelerate the wear of the moving and static ring planes, forming grooves or ring grooves, which affects the sealing performance.
2. Spring failure
As an important component of mechanical seals, the preload of springs directly affects the fit degree between the moving and stationary rings. After long-term operation, the spring may fail due to corrosion, breakage or loosening, resulting in water leakage.
In addition, if suspended particles or crystals in the medium accumulate in the spring gap for a long time, it will also hinder the normal operation of the spring, causing the compensation sealing ring to be unable to float and subsequently leading to leakage.
3. Deviation of perpendicularity between the sealing end face and the centerline of the shaft
When the perpendicularity deviation between the sealing end faces of the dynamic and static rings and the centerline of the shaft is too large, it will cause the sealing end faces to not fit tightly, resulting in leakage. This situation is usually caused by improper installation or equipment vibration.
4. Large axial movement
Large axial movement of the sealing shaft or quality issues with other sealing-related components can also cause mechanical seal leakage.
5. The O-ring is damaged
As an auxiliary sealing element, if the O-ring is damaged or aged, it will also reduce the sealing performance of the mechanical seal, leading to water leakage.
6. Cavitation phenomenon
In high-temperature medium environments such as hot water pumps, excessively high water temperature can generate steam. When the steam enters the pump cavity and cannot be discharged, it will cause the mechanical seal to operate in a water-deficient state, thereby leading to dry grinding failure and cavitation, resulting in water leakage.
7. Dry grinding damage
Dry grinding of mechanical seals due to water shortage operation or other reasons will severely damage the planes of the moving and static rings, causing a sharp decline in sealing performance and resulting in water leakage.
Iii. Solutions
For the problem of mechanical seal leakage, the following solutions can be adopted:
1. Regular inspection and maintenance: Regularly inspect mechanical seals to promptly identify and address issues such as wear and cracks.
2. Correct installation: Operate strictly in accordance with the installation specifications to ensure that the perpendicularity of the moving and stationary ring planes to the shaft centerline meets the requirements, and the spring preload is moderate.
3. Improve water quality: For media with poor water quality and containing particles, measures such as filtration and purification should be taken to reduce the wear of mechanical seals caused by impurities.
4. Install automatic air release valves: Install automatic air release valves on equipment that is prone to generating steam, such as hot water pumps, to promptly remove the steam inside the pump chamber.
5. Replace sealing elements: For aged or damaged O-rings and other sealing elements, they should be replaced in a timely manner.
6. Avoid dry grinding: Ensure that the equipment has sufficient lubrication and cooling conditions during normal operation to prevent the occurrence of dry grinding.
Through the implementation of the above measures, the incidence of mechanical seal leakage can be effectively reduced, ensuring the normal operation of the equipment and production efficiency.
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