A aspirator made of copper. The water inlet is at the top and the water outlet is at the bottom. The air inlet is on the side.

An aspirator is a device that makes vacuum, because of the Venturi effect. In the aspirator, fluid flows through it. The tube gets more thin, making the fluid flow faster, and making the pressure smaller. Then, vacuum is taken from it. The aspirator is also known as an ejector or a filter pump.