Vacuum Pump for Degassing

A vacuum degassing system works by using a vacuum pump to create a low-pressure environment that causes dissolved gases, air bubbles, and volatile substances to be removed from a material, typically liquids or sometimes solids. Here’s how the system generally works, step-by-step:

1. Loading the Material

The material that needs degassing (e.g., resin, oil, liquid metals, chemicals, or food products) is placed into a degassing chamber or vessel. This chamber is usually sealed to allow the creation of a vacuum within.

2. Creating a Vacuum

A vacuum pump is used to evacuate the air from the chamber, reducing the internal pressure. As the pressure decreases, the gases dissolved in the liquid (or trapped in solid or semi-solid materials) begin to come out of solution, rising to the surface of the material.

3. Gas Release

As the vacuum increases, the solubility of gases within the material decreases, causing the gases to form bubbles and rise to the surface. This happens because, at lower pressures, the gas molecules are no longer "held" in the liquid phase and start to escape.

4. Gas Removal

The released gases (such as air, moisture, or volatile compounds) are drawn out by the vacuum pump, which keeps the chamber under a sustained low pressure. The gases are vented out of the system, preventing them from re-entering the material.

5. Maintaining Vacuum or Controlled Pressure

Some systems may allow for the gradual introduction of controlled pressure or a backfill of inert gases (like nitrogen) after degassing to ensure that the material is free of impurities and remains stable. In certain applications, the material might be kept under a mild vacuum for an extended period to allow for the maximum removal of gases.

6. End of Process

Once the gases have been sufficiently removed, the vacuum is released, and the degassed material is ready for further processing, packaging, or use. In certain systems, the material may be collected in a different chamber, or the vacuum process may be repeated for additional purity.

Vacuum plays a crucial role in the degassing process by providing the low-pressure environment needed to extract dissolved gases, air bubbles, and volatile substances from liquids, solids, or mixtures. Here's how and where vacuum is used in different stages of the degassing process:

1. Vacuum Creation in the Degassing Chamber

• Where it’s used: In the vacuum chamber or degassing vessel where the material (such as resin, oil, liquid metal, or chemicals) is placed.
• Purpose: A vacuum pump is used to create a low-pressure environment inside the chamber. By reducing the pressure, the solubility of gases in the material decreases, allowing these gases to escape. This is the first key application of vacuum in the process.

2. Vacuum for Gas Extraction

• Where it’s used: In the vacuum pump system connected to the degassing chamber.
• Purpose: The vacuum pump draws out the released gases (such as air, moisture, volatile chemicals, or dissolved gases) from the chamber. As the pressure inside the chamber drops, these gases form bubbles and rise to the surface of the material, where they are sucked into the vacuum pump and removed. This is a direct use of vacuum to extract unwanted gases.

3. Vacuum During Gas Release

• Where it’s used: Within the material itself (in cases where gases are dissolved or trapped within liquids or solids).
• Purpose: When the pressure is reduced, dissolved gases (such as oxygen or nitrogen) within the material come out of solution and form bubbles. The vacuum helps to drive these bubbles to the surface, allowing them to escape into the chamber, making vacuum the driving force for releasing the trapped gases.

4. Vacuum for Maintaining Purity

• Where it’s used: In high-precision industries, such as pharmaceuticals, food processing, and high-quality resin production.
• Purpose: Vacuum can be maintained to prevent external contaminants from entering the degassing chamber. For instance, in food packaging or chemical manufacturing, a vacuum is applied to ensure that the material stays free from contamination while gases are removed, ensuring product stability and purity.

5. Vacuum for Controlling the Rate of Degassing

• Where it’s used: In the control system of the vacuum degassing unit.
• Purpose: The vacuum level can be adjusted to control how quickly and efficiently gases are extracted from the material. The controlled application of vacuum allows for precise degassing, especially in sensitive applications like pharmaceutical manufacturing or semiconductor production. In these cases, the vacuum is not only used to remove gases but also to ensure a controlled and consistent process.

6. Vacuum for Finalizing the Degassing Process

• Where it’s used: At the end of the degassing cycle.
• Purpose: Once sufficient degassing has occurred, the vacuum is slowly released to bring the pressure back to normal atmospheric levels. However, some systems may continue to apply a mild vacuum or replace the vacuum with an inert gas (e.g., nitrogen) to prevent reabsorption of unwanted gases. This is especially important in critical applications, such as degassing food products or high-performance materials.

When selecting the best vacuum pumps for degassing, it's important to consider the specific needs of your application, such as the type of material being degassed, the required vacuum level, and the efficiency of the pump in removing gases. Here are some of the best types of vacuum pumps for degassing, along with examples of popular models:

1. Rotary Vane Pumps

Best for: General-purpose degassing applications, including resins, oils, and solvents.

• How they work: Rotary vane pumps use a set of vanes that rotate within a cavity to create a vacuum. They are reliable and capable of achieving deep vacuum levels, making them suitable for most degassing applications.
• Advantages: Efficient, widely available, and durable.
• Popular models:
  • Edwards E2M series: Known for reliability and performance in degassing applications.
  • Leybold D16B: A solid choice for degassing applications in laboratories or smaller-scale production environments.

2. Dry Scroll Pumps

Best for: Clean degassing of oils, resins, and chemicals where contamination from pump oil is a concern.

• How they work: Scroll pumps use two spiral-shaped scrolls to compress and evacuate gas, offering a dry and oil-free pumping solution.
• Advantages: No oil contamination, high reliability, and low maintenance.
• Popular models:
  • Agilent / Varian IDP-3: A high-performance dry scroll pump suitable for clean degassing processes.
  • Vacuum Industries GS Series: Offers oil-free operation and reliable performance for a variety of degassing applications.

3. Diaphragm Pumps

Best for: Low-volume degassing tasks with minimal gas load, or applications that require very clean environments.

• How they work: Diaphragm pumps use a flexible diaphragm to move gas through the pump and create a vacuum. These are ideal for low-pressure degassing processes and can operate with minimal maintenance.
• Advantages: Compact, oil-free, and suitable for lab and small-scale applications.
• Popular models:
  • KNF Neuberger N838: Known for its versatility and precision in laboratory degassing applications.
  • Pfeiffer DUO 1.5: A reliable diaphragm pump for light degassing needs.

4. Rotary Piston Pumps

Best for: High-performance degassing where deeper vacuum levels and high pumping speeds are required, especially in larger industrial processes.

• How they work: Rotary piston pumps use a piston to create a vacuum by displacing gas within a cylinder. These pumps offer high throughput and can operate at deeper vacuum levels compared to other types.
• Advantages: Capable of high vacuum levels and good for high-gas-load applications.
• Popular models:
  • Leybold D65B: Known for its robust performance in industrial degassing applications.
  • Busch R5: A heavy-duty rotary piston pump used in industrial degassing, offering excellent durability and performance.

5. Liquid Ring Pumps

Best for: Degassing of larger volumes of materials, especially when dealing with wet or vaporous substances.

• How they work: Liquid ring pumps create a vacuum by using liquid (typically water) to seal and compress gas within a rotor. They are efficient at handling both liquid and gas phases.
• Advantages: Effective for handling vapors and gases, often used in chemical or heavy industrial degassing processes.
• Popular models:
  • Gardner Denver L series: Provides reliable and efficient degassing performance, especially for larger or more demanding applications.
  • Busch Mink: Known for handling higher gas loads and wet applications, such as degassing in chemical processing.

6. Turbo Molecular Pumps

Best for: Ultra-high vacuum (UHV) degassing for highly sensitive applications, like semiconductor production or research labs.

• How they work: Turbo molecular pumps use high-speed rotating blades to impart momentum to gas molecules and move them towards the exhaust port. These pumps are capable of reaching ultra-high vacuum levels.
• Advantages: Provide ultra-high vacuum levels, ideal for sensitive materials.
• Popular models:
  • Pfeiffer HiPace 80: A high-performance turbo pump ideal for precise, high-vacuum degassing applications.
  • Edwards nEXT Turbo: A compact, high-performance turbo molecular pump used in high-end scientific applications.

• Vacuum level required: Different pumps achieve different vacuum levels. For deep vacuum, you may need rotary vane, liquid ring, or turbo molecular pumps, while diaphragm and scroll pumps are ideal for less intensive applications.
• Gas load: The amount of gas to be evacuated impacts the pump choice. Heavy-duty pumps like liquid ring or rotary piston pumps are needed for high gas loads.
• Contamination: If contamination is a concern, oil-free pumps like dry scroll or diaphragm pumps are preferred.
• Material compatibility: Ensure the pump materials are compatible with the substances you're degassing, especially in chemical or food industries.
• Maintenance and reliability: Some pumps require more maintenance than others, so choose one based on your available resources and the required reliability for your application.

When purchasing a vacuum degassing system, there are several key factors you need to consider to ensure that the system will meet your specific needs and provide efficient, reliable, and cost-effective performance. Below are the most important points to keep in mind:

1. Type of Material to Be Degassed

• Consideration: The material you're degassing (e.g., resin, oil, liquid metal, or chemicals) will influence the type of vacuum degassing system you need. Different materials may require different vacuum levels, temperatures, and pumping mechanisms.
• Example: For viscous liquids like resins, a system that can handle high gas loads might be necessary, whereas a smaller, more compact system might suffice for lighter liquids.

2. Required Vacuum Level

• Consideration: Different applications require different vacuum levels. Some processes need a deep vacuum (e.g., for sensitive or high-purity applications), while others may only require moderate vacuum levels.
• Example: If you need to remove very low concentrations of dissolved gases, you may require a system that can achieve high vacuum levels (e.g., rotary vane or turbo molecular pumps).

3. Pump Type and Performance

• Consideration: The type of vacuum pump (rotary vane, diaphragm, dry scroll, liquid ring, or turbo molecular) impacts the overall system performance. Each type has its own advantages and trade-offs in terms of vacuum depth, contamination, and maintenance requirements.
• Example: For clean, oil-free applications, a dry scroll pump or diaphragm pump might be ideal. For high gas loads or wet processes, a liquid ring pump may be more suitable.

4. Gas Load Capacity

• Consideration: The vacuum system needs to handle the amount of gas that will be removed from the material. High gas load capacity is crucial for processes that release large amounts of gas.
• Example: A liquid ring or rotary piston pump is well-suited for high gas load processes, whereas diaphragm pumps are typically better for low gas loads.

5. Throughput and Processing Speed

• Consideration: How quickly the system can evacuate the gases and process the material is important for production efficiency. The throughput should match the scale of your operation, whether small-scale lab applications or large-scale industrial processes.
• Example: In high-volume applications, you may need a rotary vane or liquid ring system with a high flow rate to keep up with the processing speed.

6. System Size and Footprint

• Consideration: The size of the vacuum degassing system is critical, especially if space is limited in your production area. Smaller systems might be more suitable for laboratory or small-scale use, while larger systems are necessary for industrial-scale processes.
• Example: Consider a compact dry scroll pump for limited space, while larger rotary piston or liquid ring systems are designed for high-volume, industrial environments.

7. Contamination Control

• Consideration: In many degassing applications, maintaining a contamination-free environment is crucial, especially in industries like pharmaceuticals, food processing, and electronics manufacturing. Oil-free pumps or systems with better filtration may be required to ensure clean operation.
• Example: Dry scroll or diaphragm pumps are excellent for oil-free operation, reducing the risk of contamination.