3. Filling and refilling

There are numerous dosing and filling systems for liquids and pasty products (table 1 ):

• in sealed systems, the filling device is in hermetic contact with the container to be filled;

• in non-sealed systems, the container to be filled is left open to the air during filling.

We also distinguish between isobaric systems, where the pressure is the same in the main tank and in the cylinders or containers, and systems with pressure differentials.