Perfusion systems and procedures for operating perfusion systems that can include a drip container, a drop detector, a perfusion conduit and at least one control valve or a syringe pump. During the procedure, at least one calibration of the measuring process and the storage of at least one calibration value are performed. A control unit regulates the control valve or the syringe pump while using at least one measurement performed by the measuring device and taking into account at least one calibrated value towards the desired flow volume.
