How to Choose the Right Degassing Vacuum Pump for Your Industrial Process

Trapped gas is a silent quality killer in industrial production. Whether you are casting epoxy resins, refining molten steel, or purifying transformer oil, dissolved and entrained gases can create voids, weaken structural integrity, and compromise the electrical properties of your finished product. Vacuum degassing solves this problem — but only if you select the right pump for the job.

This guide breaks down how vacuum degassing works, which industries depend on it, and what to look for when choosing a degassing vacuum pump that matches your process requirements.

What Is Vacuum Degassing and How Does It Work?

Vacuum degassing is the process of removing dissolved or entrained gases from liquids, molten metals, and viscous compounds by exposing them to reduced pressure. The underlying physics follows Henry's Law: as pressure drops, gas solubility decreases, causing dissolved gases to come out of solution, form bubbles, rise to the surface, and escape.

In practice, this means placing a mixed resin, molten steel, or process oil inside a vacuum chamber or circulation loop, then applying a controlled vacuum level for a set period. The result is a denser, stronger, and more uniform material with fewer defects.

Which Industries Rely on Vacuum Degassing?

Vacuum degassing plays a critical role across multiple sectors. Each industry has unique requirements for vacuum depth, pumping speed, and vapor tolerance.

Steel and Metallurgy

Vacuum degassing removes hydrogen from molten steel to prevent hydrogen flaking — a defect that reduces yield strength and can lead to catastrophic structural failure. It also lowers dissolved carbon content to produce more ductile steel grades. These processes demand deep vacuum levels, often achieved with multi-stage steam ejector systems or hybrid ejector and liquid ring combinations.

Resin, Epoxy, and Polymer Manufacturing

When resins and hardeners are mixed, air bubbles become trapped in the compound. If not removed before curing, these bubbles create nodules, cavities, and hollows that weaken the final cast or coating. Vacuum degassing is essential in casting, potting, and encapsulation applications where trapped gas can compromise both structural integrity and appearance.

Oil and Lubricant Processing

Hydraulic fluids, lubricating oils, and transformer oils all benefit from vacuum degassing. Removing dissolved air and moisture prevents foaming, oxidation, and cavitation in downstream equipment. In electrical applications, degassed transformer oil delivers improved dielectric strength and longer service life.

Electronics and Semiconductor

Encapsulation of electronic components requires bubble-free potting compounds. Even microscopic voids can cause electrical breakdown and premature component failure. Vacuum degassing ensures reliable insulation and long-term performance in demanding environments.

Food and Beverage

Wine, juice, and edible oil producers use vacuum degassing to remove dissolved CO2 and oxygen, improving flavor stability and extending shelf life without chemical additives.

What Types of Vacuum Pumps Are Used for Degassing?

The right pump technology depends on your vacuum level requirements, the nature of the process vapors, and whether you need a standalone pump or a complete system.

Five Factors to Consider When Selecting a Degassing Vacuum Pump

• Required vacuum level: Match the pump's ultimate vacuum to your process needs. Steel degassing may require deep vacuum below 1 mbar, while resin casting often works well at 50 to 200 mbar.
• Pumping speed: Higher viscosity materials release gas more slowly. Choose a pump with enough capacity to handle the gas load within your cycle time.
• Vapor and contamination tolerance: If your process generates solvent vapors, moisture, or fine particles, select a pump designed to handle them without performance loss or damage.
• Oil-free vs. oil-sealed: Oil-sealed pumps offer lower upfront cost and simpler maintenance. Oil-free dry pumps eliminate contamination risk and are mandatory in food, pharmaceutical, and electronics applications.
• Total cost of ownership: Consider energy consumption, oil changes, spare parts availability, and expected service intervals — not just the purchase price.

Practical Tips for Better Vacuum Degassing Results

Even the best pump cannot compensate for poor process setup. Keep these practical points in mind:

• Use a container large enough to accommodate material expansion — mixed resins can expand two to six times their initial volume under vacuum.
• Monitor pot life and viscosity. High-viscosity materials take longer to degas, and excessive vacuum time can evaporate volatile components and alter curing behavior.
• Warm up the vacuum pump before starting the process. A warm pump handles condensable vapors more efficiently and reaches its rated vacuum level faster.
• Maintain your pump regularly. Check oil level and clarity on oil-sealed models, and replace cloudy or contaminated oil immediately.

Frequently Asked Questions