Understanding The Side Vacuum Exhaust System: What You Need To Know

In the plastic extrusion industry, vacuum degassing is a critical step in ensuring product quality by removing volatile substances from the raw materials. While traditional vacuum systems are typically mounted on top of the extruder, the side vacuum exhaust system has gained increasing attention in recent years. What exactly is the difference between the two, and what are the benefits of using a side vacuum system? This article summarizes insights from a professional interview to explain it clearly.

Side Vacuum vs. Top Vacuum: What’s the Structural Difference?

Conventional vacuum systems are usually installed on top of the extruder and work by applying negative pressure to extract volatile components. However, this setup can sometimes cause a common issue—material overflow, where material gets sucked into the vacuum line, leading to contamination or equipment malfunction.

The side vacuum exhaust system is designed to eliminate this problem. With the vacuum port located on the side, and the screw rotating inward, material is constantly being pressed deeper into the screw channel. This movement naturally prevents material from escaping through the vacuum port. As a result, side vacuum systems offer greater stability and reduce maintenance needs caused by material overflow.

Is a Higher Vacuum Level Always Better?

This is a common misconception. Many assume that “the stronger the vacuum, the better the degassing,” but this is not always true. In degassing, what really matters is a stable negative pressure and sufficient air extraction capacity.

As one experienced operator put it:

"What we aim for is stable negative pressure. It doesn’t need to be extremely high, but it must be steady. The key is that the vacuum line shouldn’t be blocked or cause material to overflow."

In fact, the effectiveness of degassing is also closely related to the screw design, temperature control, and screw speed—not just the strength of the vacuum.

What Factors Affect Degassing Performance?

Besides the vacuum system itself, the following elements play a crucial role in degassing efficiency:

• Temperature Control: The right temperature is needed to release volatile substances. If the temperature is too low, they won’t fully evaporate; if too high, the material might degrade.

• Screw Speed: Determines how long the material stays in the degassing zone. The right speed helps optimize gas removal.

• Screw Element Design: Different combinations of screw elements affect the distribution and shearing of the material, which directly influences how efficiently gases can escape.

In Summary

The side vacuum exhaust system offers a more stable and secure degassing solution, especially for processes where material overflow is a concern or where there are high levels of volatiles. While it may take up slightly more space due to the additional side-mounted unit, the benefits in process reliability and ease of maintenance are clear.

When choosing a vacuum system, it’s essential to consider the overall process needs, material properties, and equipment layout—not just the vacuum strength. As one expert rightly said:

"It’s not about how strong the vacuum is, but whether it’s the right kind of vacuum for your process."

NANJING HAISI is professional manufacturer of Plastic Machine, we supply Twin Screw Extruder, Single Screw Extruder, Plastic Recycling Extruder, Two Stage Extruder, Lab Scale Extruder, Mixing and Feeding Machine, Cooling and Pelletizing Machine, Crushing Machine and so on.