Tech Team · Kintek Solution

The vacuum level required for distillation depends on the specific application, the type of solvent or material being distilled, and the desired boiling point reduction. Generally, vacuum distillation requires a vacuum pump capable of achieving a pressure range between 1 mbar (for basic distillation tasks) and 50 microns or lower (for short-path distillation or high-boiling-point solvents). Oil-free diaphragm pumps are suitable for simpler tasks, while chemically resistant rotary vane pumps are preferred for more demanding applications, such as short-path distillation. The choice of pump and vacuum level should align with the chemical resistance, ultimate vacuum depth, and process requirements to ensure efficient and reproducible results.

Key Points Explained:

1. Vacuum Levels for Different Distillation Applications:

   • Basic Distillation: For tasks like suction, concentration, or drying, a vacuum of up to 1 mbar is usually sufficient. This can be achieved using an oil-free diaphragm pump, which is ideal for simpler applications.
   • High-Boiling-Point Solvents: Distilling solvents with high boiling points requires a deeper vacuum. A water-free and oil-free diaphragm pump with a low ultimate vacuum is suitable for this purpose.
   • Short-Path Distillation: This process demands a deeper vacuum, typically at least 50 microns, to achieve efficient separation of compounds. Rotary vane pumps are preferred due to their ability to handle chemically abrasive materials and achieve extreme vacuum depths.

2. Types of Vacuum Pumps:

   • Oil-Free Diaphragm Pumps: These are suitable for basic distillation tasks and applications where chemical resistance is not a primary concern. They are easy to maintain and provide sufficient vacuum levels for many common distillation processes.
   • Rotary Vane Pumps: These are recommended for more demanding applications, such as short-path distillation, due to their superior vacuum depth (down to 50 microns or lower) and chemical resistance. Regular oil changes are essential to maintain performance.

3. Chemical Resistance and Pump Maintenance:

   • Chemical Resistance: For processes involving chemically abrasive materials, such as short-path distillation, a chemically resistant pump is crucial. Rotary vane pumps are often preferred because they can handle harsh chemicals without degradation.
   • Maintenance: Regular maintenance, such as changing the pump oil before each distillation, ensures optimal performance and prolongs the pump's lifespan. This is particularly important for rotary vane pumps used in demanding applications.

4. Process Requirements:

   • Fast and Sensitive Vacuum Control: For samples prone to superheating or foaming, a vacuum system with fast and highly sensitive control is necessary to prevent sample degradation and ensure reproducibility.
   • Short Process Times: Efficient vacuum control is also critical for achieving short process times, which is essential in high-throughput or time-sensitive applications.

5. Boiling Point Reduction:

   • The primary purpose of vacuum distillation is to lower the boiling point of the liquid, enabling distillation at lower temperatures. This is particularly useful for heat-sensitive materials or high-boiling-point solvents. The vacuum level directly influences the boiling point reduction, with deeper vacuums allowing for lower boiling points.

6. Equipment Selection Considerations:

   • When selecting a vacuum pump for distillation, consider the following factors:
     • Ultimate vacuum depth required for the specific application.
     • Chemical compatibility with the solvents or materials being distilled.
     • Maintenance requirements, such as oil changes for rotary vane pumps.
     • Process control capabilities, including sensitivity and speed of vacuum adjustment.

By carefully evaluating these factors, you can choose the appropriate vacuum pump and achieve the necessary vacuum level for your distillation process, ensuring efficient and reliable results.

Summary Table:

Application	Vacuum Level	Recommended Pump Type
Basic Distillation	Up to 1 mbar	Oil-Free Diaphragm Pump
High-Boiling-Point Solvents	Deeper vacuum	Water-Free Diaphragm Pump
Short-Path Distillation	50 microns or lower	Chemically Resistant Rotary Vane Pump

Key Considerations:

• Chemical Resistance: Essential for harsh materials.
• Maintenance: Regular oil changes for rotary vane pumps.
• Process Control: Fast and sensitive vacuum adjustment for reproducibility.

Need help selecting the right vacuum pump for your distillation process? Contact our experts today for personalized advice!