Safety device for a single-use mixing or storage system

A safety device for a single-use mixing or storage system for use in a biopharmaceutical process, the safety device comprising:

• a flexible bag made from a film material,
• a support structure configured to receive the bag and support the bag in plural directions, wherein the support structure is a container surrounding the bag on all sides except on a top side of the bag, and allows an expansion of the bag in at least one expansion direction including on the top side of the bag,
• a detection unit adapted to detect the expansion of the bag in the expansion direction, and a control unit connected to the detection unit and adapted to initiate a safety measure in response to a detection of the expansion of the bag in the expansion direction on the top side of the bag that exceeds a given threshold signifying an overfilling of the bag,
• wherein the detection unit includes a sensor element arranged to come into contact with the bag only during a latter portion of the expansion, when the bag expands so that the sensor element is translated or rotated away from the support structure by the expansion of the bag in the expansion direction on the top side of the bag, and
• wherein the sensor element includes a pivotable lever.