During manufacture of dairy products, raw milk travels between successive processes through stainless-steel pipework. Rotary-shaft control valves maintain process sequences correctly, ensuring that no cross-contamination occurs during CIP cleaning after each batch is completed. Robust washdown inductive sensors, mounted on existing rotary actuators, monitor control-valve status around the clock, providing real-time positional feedback to a plant-wide control system in a simple, cost-effective manner.