Abstract: An apparatus is described herein that includes an elongate arm and a rotating nozzle rotationally coupled to an end of the elongate arm. An electronic processor is communicatively coupled to a communication interface of an in-line pressure sensor of a liquid feed channel from a pump providing a fluid that both drives rotation of the rotating nozzle and cleans an interior surface of a vessel. The electronic processor analyzes a digitized measured pressure signal data stream provided by the pressure sensor to provide a real-time indication of rotational status of the rotating nozzle during a cleaning operation of the interior surface of the vessel.