Two-stage vacuum pumps are more productive, unlike single-stage pumps. Unlike single-stage pumps, in two-stage pumps, peak performance is achieved at pressures close to the maximum vacuum. The main advantage of two-stage pumps is a more stable vacuum with high performance. In two-stage water-ring vacuum pumps, cavitation is less likely to occur (the formation of cavities (cavitation bubbles, or cavities) filled with gas, steam or a mixture of them in the liquid).