Pump mechanical seal leakage reasons

Pumps are equipped with a wide variety of mechanical seals, available in different models. However, leaks typically occur at five main points: 1. The seal between the sleeve and the shaft 2. The seal between the rotating ring and the sleeve 3. The seal between the rotating and stationary rings 4. The seal between the stationary ring and its seat 5. The seal between the cover and the pump body In general, leaks between the extended shaft and the seal cap or between the cover and the pump body are easier to detect and fix. However, when dealing with liquefied gas, high-pressure, or toxic substances, careful observation is essential. Other leakage points are more difficult to identify visually, requiring long-term management, maintenance experience, and analysis based on observed symptoms to reach accurate conclusions. **First, Analyze and Identify the Leak** 1. **Static leakage during installation**: If the mechanical seal is installed properly, a static test should be conducted to check for leakage. A small amount of leakage usually indicates an issue with the rotating or stationary ring seal, while a large leak suggests damage to the friction surfaces. During initial inspection, if the leakage doesn’t change significantly when the shaft rotates, it’s likely a problem with the static or dynamic ring seal. If the leakage changes noticeably during rotation, the friction rings may be damaged. If the medium leaks along the axis, the dynamic ring seal is likely at fault. If the fluid sprays outward or leaks from a hole, the static ring is probably failing. Multiple leakage paths can exist, but one is usually dominant. Careful observation and understanding of the structure are key to accurate diagnosis. 2. **Leakage during commissioning**: After a static test, the centrifugal force generated by high-speed operation helps reduce leakage. Therefore, any leakage during testing is often due to damage to the dynamic or static friction rings. Common causes include: - Excessive axial force from cavitation, pressure fluctuations, or prolonged operation - Over-compression during installation leading to severe wear - Too tight a seal on the rotating ring, preventing proper adjustment - Too loose a seal on the static ring, causing it to move out of position - Presence of solid particles in the working medium that enter the friction pair - Incorrect design or material selection leading to inadequate sealing performance These issues often appear during trial runs and may be resolved by adjusting the static ring seat, but most require disassembly and replacement of the seal. 3. **Sudden leakage during normal operation**: Sudden leaks during normal operation are often caused by wear, reaching the end of service life, or improper operation and maintenance. Common causes include: - Cavitation, long-term pressure holding, or evacuation leading to seal damage - Low pump output causing heat buildup and media vaporization - Excessive return flow damaging the seal through sediment impact - Long downtime without manual turning before restarting, causing adhesion and tearing - Corrosive or polymer-rich media affecting the seal - Rapid temperature changes - Frequent operational adjustments - Sudden power failures or shutdowns If not detected in time, sudden leaks can lead to serious accidents, so prompt action is crucial. **Second, Common Maintenance Errors with Mechanical Seals** 1. **More spring compression means better sealing**: In reality, excessive compression leads to rapid wear, potential burning, and loss of dynamic ring adjustment capability, ultimately causing seal failure. 2. **Tightening the rotating ring as much as possible**: Over-tightening increases wear between the seal ring and sleeve, reduces axial flexibility, and may cause deformation, all of which negatively affect the seal. 3. **Tightening the static ring excessively**: While a tighter static seal is generally better, over-tightening can deform the ring, especially if made of brittle materials like graphite, and make installation and removal difficult, increasing the risk of damage. 4. **Tightening the impeller lock too much**: Shaft leakage is common, but over-tightening the lock can prematurely damage the shaft pad. Instead, maintaining a slight compression allows the lock to function properly and keep the shaft sealed. 5. **New seals are always better than old ones**: While new seals may perform better initially, poor quality, incorrect sizing, or improper material selection can still cause issues. In some cases, older seals with minimal wear may perform better, especially in polymer-rich environments where deposits help maintain the seal. 6. **Removing the seal is always better than leaving it**: Sometimes, a leak can be fixed by adjusting the seal rather than replacing it. This saves resources and improves maintenance skills over time. Proper understanding and careful handling of mechanical seals are essential for effective pump maintenance and long-term reliability.

Nut Packing Machine

nut packaging machine,cashew packaging machine,almond packing machine,peanut packaging machine

FOSHAN HIGH-TECH MACHINERY EQUIPMENT CO., LTD , https://www.packingweigher.com