Vacuum level semi-automatic filling machines use the rim at the top of the container to form an airtight seal around the filling nozzle.
This airtight seal creates a vacuum within the bottle which draws free-flowing liquids from a supply tank into the bottle, via specially designed nozzles. These nozzles have a small hole on the side which is connected to a small internal tube.
The height of this hole in relation to the top of the container during filling determines the level of liquid dispensed. The small hole in the nozzle scavenges excess liquid from the filling process and collects it in a receiver for reuse.
Vacuum level filling machines fill containers to the same height each time, rather than dispensing the same volume. This is particularly useful for glass bottles which will be side-by-side on display shelves in shops. Glass bottles vary in capacity quite a lot, yet vacuum-level filling ensures the level each bottle is filled to is the same, giving a consistent appearance from one bottle to the next. Vacuum level filling requires rigid containers which won’t collapse under a vacuum.