In oil-lubricated (rotary vane) vacuum pumps, oil not only provides lubrication, but also seals the clearance between the vanes and the housing, and dissipates the heat generated during compression. Therefore, the condition of the oil directly determines the vacuum level the pump can achieve and its service life.

Oil level and color

The oil level must be checked through the sight glass while the pump is not running; the level should be between the markers on the glass. New oil is clear and light in color. Darkened, foamy, or cloudy oil indicates overheating, moisture, or contamination from the pumped medium and must be changed.

Oil change interval

The change interval varies depending on operating hours, temperature, and the cleanliness of the pumped medium. Intervals can be extended in applications pumping clean and dry air; more frequent changes are required in humid, vaporous, or dusty environments. It is safest to take the manufacturer's recommended interval as a baseline and advance it according to the appearance of the oil.

Only oil manufactured specifically for vacuum pumps and of the recommended viscosity should be used. Mixing different types of oil may lead to foaming and loss of vacuum.

Exhaust (oil mist) filter

The exhaust filter traps the oil mist in the air discharged from the pump. As the filter clogs, pressure builds up inside the pump, the motor labors, and oil smoke begins to appear from the exhaust. These symptoms indicate that the filter needs to be replaced.

Suction filter

The filter on the suction side prevents dust and particles from entering the pump. A clogged suction filter reduces the flow rate, while a torn filter accelerates the wear of the vanes and housing. In dusty applications, the filter must be cleaned or replaced regularly.

Short maintenance checklist

  • Weekly: oil level and color, unusual noise or heating
  • Periodically: oil change, cleaning of the suction filter
  • When oil smoke is observed at the exhaust: exhaust filter replacement
  • Before prolonged shutdowns: running the pump for a few minutes with the gas ballast open to expel moisture

You can request original oils, filters, and spare parts for your ZYVP series pumps from our Spare Parts page.