Innovative non-invasive ultrasound method for whisky cask liquid level measurement

Regular measurement and inspection of whisky casks are crucial for ensuring quality and effective inventory management. This process helps detect issues such as leaks, damage, and contamination that can harm the whisky’s condition. Additionally, monitoring the whisky level provides valuable insights into maturation progress, evaporation rates, and production planning to account for expected losses. Currently, the industry relies on dipsticks and pressure sensors to measure liquid levels in casks. Dipsticks require moving casks from high shelves, risking human safety, the utilisation of extensive resources and necessitating cask opening, which has inherent issues. Pressure sensors, installed inside casks, are sensitive to temperature, limiting their accuracy and suitability for warehouse testing. This paper presents a new non-invasive method using ultrasound to measure liquid levels in wooden casks. An external ultrasonic probe glides along the surface of the cask. By leveraging the distinct ultrasonic acoustic properties in the liquid and the air, the sensor can detect the upper boundary of the liquid, thereby indicating the whisky level. Since this new method only needs to access a small portion of the cask to measure the level, it enables distilleries to accurately monitor cask contents on-site, reducing the costs and risks associated with moving casks. The paper also includes quantitative data on ultrasonic properties such as moisture, velocity, and signal attenuation for various cask samples. The prototype system successfully demonstrated this approach on a retired Ex-Bourbon whisky cask, providing precise liquid level measurements on different surfaces and storage orientations without the need for cask opening. It achieved centimetre-level accuracy compared to dipstick reference readings. •Proposed a new, non-invasive method to measure liquid levels in wooden casks.•Quantitatively assessed ultrasonic properties in two cask samples.•Demonstrated and verified the method using a retired Ex-Bourbon cask.•Achieved centimetre-level accuracy independent of the cask storage orientation.