Pusher vs. Non-Pusher Mechanical Seals: What’s the Difference?

Mechanical seals are essential components in many industrial applications, including pumps, compressors, and mixers. They are used to prevent leakage of fluids and gases from the equipment, ensuring safe and efficient operation. There are two main types of mechanical seals: pusher and non-pusher. In this post, we will explore the differences between these two types of seals and their respective advantages and disadvantages.

Pusher Mechanical Seals

Pusher mechanical seals are designed to maintain a constant contact force between the seal faces, even as the faces wear down over time. This is achieved by using a spring-loaded mechanism that pushes the seal faces together. As the faces wear down, the spring compresses, maintaining the contact force. Pusher seals are commonly used in applications where the seal faces are subject to high pressures and temperatures, as they can better withstand these conditions.

Advantages of Pusher Mechanical Seals:

– Can maintain a constant contact force, even as the faces wear down
– Can better withstand high pressures and temperatures
– Can be used in applications with high shaft speeds

Disadvantages of Pusher Mechanical Seals:

– More complex design, which can lead to higher costs
– Can be more difficult to install and maintain

Non-Pusher Mechanical Seals

Non-pusher mechanical seals, also known as “balanced” seals, do not use a spring-loaded mechanism to maintain contact force. Instead, they rely on the pressure of the fluid being sealed to create a balance between the seal faces. This allows the faces to remain in contact even as they wear down. Non-pusher seals are commonly used in applications where the seal faces are subject to low pressures and temperatures.

Advantages of Non-Pusher Mechanical Seals:

– Simpler design, which can lead to lower costs
– Easier to install and maintain
– Can be used in applications with low shaft speeds

Disadvantages of Non-Pusher Mechanical Seals:

– May not be suitable for applications with high pressures and temperatures
– Contact force may decrease as the faces wear down, leading to leakage

Conclusion

In summary, pusher and non-pusher mechanical seals have different designs and are suitable for different applications. Pusher seals are better suited for high-pressure and high-temperature applications, while non-pusher seals are better suited for low-pressure and low-temperature applications. When selecting a mechanical seal, it is important to consider the specific requirements of the application to ensure optimal performance and reliability.