Mechanical seal theory

Summary

The video explains the technical aspects of mechanical seals used in various equipment. It highlights the role of the housing, shaft, and seal faces in preventing leaks and ensuring smooth operation. The key challenge is sealing the gap between the rotating shaft and the housing while allowing rotation. Different seal components, such as rotating and stationary seals, secondary seals, and springs, work together to prevent leakage. The importance of selecting the right materials for optimal performance and the need for replaceable seal faces are emphasized, ensuring durability and cost-effectiveness in maintaining machinery.

Takeaways

• 😀 The shaft initiates rotary motion within the housing, and the gap between them must be sealed.
• 😀 The shaft requires clearance for rotation, and seal faces are perpendicular to the axis.
• 😀 Proper support of the housing and shaft is essential for the seal's performance.
• 😀 Seal faces wear out due to friction, leading to leakage, but ideally, only the seal faces should be changed.
• 😀 The shaft and housing are too expensive to use as wearing parts, making exchangeable seal faces more efficient.
• 😀 A stationary seat at the housing with a seal face on the shaft allows for optimal material use and reduces leakage.
• 😀 The mechanical seal design includes five components: rotating seal face, stationary seat, secondary seals, and a spring.
• 😀 When the shaft and seal faces rotate at the same speed, no relative movement occurs, preventing leakage.
• 😀 The sealing system works effectively when no relative movement happens between the shaft and the stationary seat.
• 😀 Secondary seals and springs can compensate for sealing gaps, even if some leakage is unavoidable.
• 😀 A perfect seal setup includes stationary and rotating faces with secondary seals, ensuring minimal leakage.

Q & A

What is the primary role of the shaft in the system described?

The shaft initiates the rotary motion within the housing.

Why is it important to seal the gap between the housing and the shaft?

The gap must be sealed to prevent leakage and ensure the proper functioning of the system as the shaft rotates.

Can rotation and sealing ever be compatible?

Yes, rotation and sealing can be compatible when the seal faces are perpendicular to the axis of the shaft and the housing, allowing the shaft to rotate while maintaining the seal.

What happens if the seal faces are not properly aligned?

If the seal faces are not properly aligned, it can cause leakage due to friction and wear.

What are the consequences of the shaft and housing being too expensive to use as wearing parts?

Since the shaft and housing are too expensive to serve as wearing parts, the seal faces should ideally be the only parts that are replaced when wear occurs.

What components make up the seal in this system?

The seal consists of a rotating seal face with a secondary seal and a spring, and a stationary seat with a secondary seal.

How do secondary seals contribute to the sealing process?

Secondary seals help maintain the seal integrity by compensating for potential leakage and applying pressure to the sealing faces.

What is the advantage of having exchangeable wearing parts like the stationary seat and seal face?

The advantage is that it allows for the optimization of materials used and reduces the cost of replacing more expensive components like the shaft and housing.

Why is proper support crucial for the seal's performance?

Proper support ensures that the seal faces are aligned correctly and that the seal can withstand higher loads without leaking.

What is the role of the spring in the mechanical seal assembly?

The spring applies pressure to the sealing face, ensuring it maintains contact with the stationary seat and compensating for any minor movement or wear that might occur.