Oil diffusion pumped vacuum system operation has been examined in the light of sputtering system requirements. It was found that cleanliness is an important problem because of the low deposition rates of the sputtering process. A model for a cleaning action of the throughput of the sputtering gas was derived. The model indicated that certain changes in the operating procedure of the vacuum system would increase the cleaning action of the sputtering gas significantly. The requirement is that the throughput of the sputtering gas be maximum. Measurements of partial pressure of O 2 vs Ar throughput show the model to be essentially correct. The action of the high throughput on oil backstreaming was also measured. It was found that high throughput reduces oil vapor backstreaming considerably.