Method for preparing a filling operation

A method for preparing a filling operation, comprising the following steps:

• providing a filling system, which comprises a liquid source, a barrier system for providing a controlled environment, a filling device arranged in the barrier system for filling a pharmaceutical liquid, a fluid path extending between the liquid source and the filling device for conducting the pharmaceutical liquid from the liquid source to the filling device, and a filter assembly arranged in the fluid path with at least one filter housing and a filter element arranged in the respective filter housing;
• introducing the pharmaceutical liquid from the liquid source into the fluid path;
• passing a defined amount of the introduced pharmaceutical liquid through the filter assembly in order to wet each filter element of the filter assembly;
• performing an integrity test of each filter element wetted with the pharmaceutical liquid;
• and
• forwarding the passed pharmaceutical liquid to the filling device in order to at least partially flush the fluid path.