Welch Vacuum Application I Gas Ballast, Oil-Seal Rotary-Vane Vacuum Pumps

Oil-sealed rotary vane pumps are widely used in medical and industrial environments for their reliability and performance. But without proper gas ballast operation, they’re prone to oil degradation, corrosion, and reduced efficiency—especially when pumping condensable vapors. This video explains how gas ballast works, when to use it, and what happens if you don’t.

Use gas ballast when:

• Pumping vapors with high condensation risk (e.g. water, alcohols, solvents)
• Operating in humid environments
• Running long cycles with variable loads
• Oil shows signs of discoloration or odor

Avoid using gas ballast when:

• Maximum vacuum depth is required
• Pumping dry gases only
• System is sensitive to air contamination

• Gas ballast is not automatic: It must be manually activated based on application needs.
• Oil contamination is preventable: Proper use of gas ballast significantly extends oil life.
• Pump performance depends on maintenance: Regular oil checks and correct ballast usage reduce downtime.
• Not all pumps are equal: Some models offer adjustable ballast flow or automatic control—check your specs.