are flexible polymer bags that are used in nearly all steps of a biotechnological production process. Primarily, bags are used for cultivation, storage, sampling and transport, as well as freezing and thawing procedures. Bags can be derived from either two-dimensional pillow-like 2D-bags or three-dimensional bags (3D-bags) according their shape. The simplest bag system is the tank liner.
When handling small volumes between 50 mL and 50 L, 2D-bags are mainly used. Larger bags with a volume of up to 200 L are also available but are used only in exceptional cases. Bags are funnel-shaped and hold a large outlet if powder needs to be handled. See powder transfer bag systems.
3D-bags have been approved for more complex applications and larger volumes. They contain up to 2500 L and are more diverse in terms of shape and fittings compared to 2D-bags 1. For better and more secure handling of the flexible bags, special container systems (see bag handling system) were developed 2, 13.