Oil diffusion pumps are part of the fluid-entrainment pump family
Leybold’s innovative heating system offers a unique advantage by reducing average energy consumption and delivering a considerably shorter warm-up time compared with conventional diffusion and oil booster pumps. It offers tailored solutions for applications needing a high pumping speed and high vacuum, a high gas throughput, or a large industrial booster pump, together with energy efficiency options such as the energy efficiency controller (EEC) to reduce your carbon footprint.
Oil diffusion pumps produce high vacuum and work with a fast stream of pump fluid in vapour form (oil vapour). All fluid-entrainment pumps share a similar pumping mechanism: the pump fluid is heated by an electric heater vessel and the oil vapour expands after passing through the jet nozzles. Gas molecules diffuse into the vapour stream and are carried out of the pumping chamber.
Momentum is transferred from the pump fluid molecules to the gas molecules in the direction of flow. The gas to be pumped is thus moved into a region of higher pressure. The technology does not wear because it needs no moving parts. In oil diffusion pumps the relevant vapour pressures rise during operation depending on the type of pump fluid (silicone or mineral oil), the temperature and the nozzle design.
The vapour jet does not enter the process chamber because it condenses on the cooled outer walls of the pump after being ejected through the nozzles. In addition, a modern, distinctive baffle design reduces oil backstreaming and oil consumption through an improved condensation surface. This simple physical mechanism makes the diffusion pump a robust technology.
The backing pressure in the pump must be low enough to allow the vapour to be discharged. Suitable backing pumps are used to ensure this, usually mechanical Leybold fore-vacuum pumps. The fore-vacuum pressure also affects the vapour jet and becomes harmful if it exceeds a certain critical limit, known as the maximum backing pressure or critical fore-line pressure.
Why a diffusion pump
- High pumping speed in high vacuum
- No moving parts — no wear
- Shorter warm-up time
- Lower oil backstreaming and consumption
- EEC option for lower energy consumption
