The invention provides a unit operation formed by a device and its use for continuous virus inactivation of a continuous flow of a process fluid. The unit operation formed by a device comprises a single inlet at one end and an outlet at the opposite end and at least one HFI, characterized in that the HFI further comprises at least one installation.

The invention provides a unit operation formed by a device and its use for continuous virus inactivation of a continuous flow of a process fluid. The unit operation formed by a device comprises a single inlet at one end and an outlet at the opposite end and at least one HFI, characterized in that the HFI further comprises at least one installation.

The present invention relates a method for incubating liquids, to a method for preparing a biopharmaceutical drug, and to a device for the preparation of a biopharmaceutical drug.