When a liquid-powered jet pump is used for vacuuming a confined space, as the gas is continuously pumped out, a certain vacuum will be formed in the container.

The ultimate vacuum is closely related to the saturated vapor pressure of the power liquid.

The selection of a vacuum pump needs to consider parameters such as the volume of the confined space or container, the air leakage rate, the amount of gas generated by the process, and the vacuum requirement, etc.

The ultimate vacuum of a water jet vacuum pump is about 3 kPa absolute pressure depending on the water temperature. A water jet vacuum pump is suitable for obtaining a rough vacuum.