The vapor stream emanates from the nozzles with supersonic speed to obtain as high a vapor stream velocity as possible. The jet stage nozzle system has 3-5 stages that results in the amazing pumping speed of Leybold oil diffusion pumps. The pump fluid vapor, which constitutes the vapor jet, is condensed at the water cooled wall of the pump housing, whereas the transported gas is further compressed (gas throughput), usually in one or more succeeding stages, before it is removed by the backing pump.
The compression ratios, which can be obtained with fluid entrainment pumps, are very high: if there is a pressure of 10-7 mbar at the high vacuum inlet port of the fluid-entrainment pump and a backing pressure of 10-1 mbar, the pumped gas is compressed by a factor of 10-6. This compression ratio ensures a stable high vacuum pressure for the application process. The ultimate pressure of fluid entrainment pumps is restricted by the value for the partial pressure of the fluid used at the operating temperature of the pump. With our high-quality diffusion pump oil LVO 500, LVO 521 and LVO540 we guarantee outstanding performance.