An aspirator is an ejector-jet pump that produces vacuum by means of the Venturi effect. It is a common device in chemistry and biology laboratories. Water aspirators are most common due to their extremely low price and ease of installation and operation. Modern water aspirators are capable of working efficiently with water pressure as low as 0.5 bar for minimum water consumption and are equipped with valves that prevent backflow and loss of vacuum when water source is disrupted. Water aspirators offer comparable pumping capacity, but the vacuum is limited by water vapor pressure.