Liquid Jet Ejector or Water Jet Ejector uses the principle of Bernoulli’s which means that when the velocity of the fluid is increased, its pressure decreases and vice versa. It uses a nozzle to convert the high-pressure energy of the fluid into kinetic energy.

As the diagram illustrates, an ejector consists of a converging nozzle, mixing chamber made up of converging section, throat and an outlet diverging section. The diffuser creates the mixing effect for the fluids. The motive fluid, which is water, enters through the inlet nozzle at a high pressure, leaves the nozzle at a high velocity, and creating a low pressure, thus generating vacuum.

The vacuum generated by the fluid which is water here, depends on the vapour pressure of water which is 4.6 kPa or 35.1 Torr at 32 °C.