A flow control system of a clinical perfusion system comprises flow control devices 110, such as pumps, valves and/or clamps, capable of controlling a fluid flow rate according to flow rate parameters from the flow control system. The flow control system comprises an indicator arrangement including a device indicator 122a, 122b on each flow control device 110 capable of providing a plurality of indications. The device indicators 122a, 122b are controllable by the flow control system to indicate an active condition of the flow control device 110 independently of the flow rate parameters. This allows the indication provided by the device indicator 122a, 122b to be adjusted for different clinical environments, and to provide colour indications that match the colour range discernible by users affected by colour vision deficiency.