Abstract
Accurate and precise monitoring of fluid is a fundamental requirement for process control in industry. Apart from temperature and pressure other parameters such as fluid level, viscosity and concentration are of special interest. Despite the current traditional fluid measuring methods, a more qualified method for obtaining better information can significantly enhance the process quality and thereby product properties. Ultrasonic sensors or sensor systems can contribute immensely in this regard. The current research work presents a contactless microcontroller-based ultrasonic fluid level measurement system. The system uses a low-power, programmable and large memory Atmega-328 microcontroller to monitor and control the generation sound pulse at 40kHz. The HC-SR04 ultrasonic module is responsible for both generation and detection of the ultrasound required for level computation and the level is displayed on the Liquid Crystal Display (LCD) unit. The device can measure fluid levels within a range of 20cm to 400cm. Fluid level measurements of three different samples, water, petrol, and kerosene were carried out with both a measuring tape and the constructed (current) device. The results indicate a difference of +1cm to +2cm with negligible percentage errors. Also, as the water level may be obtained while filling or emptying the tank, the volumetric flow may be estimated. However, when the fluid level is so low that it is not detectable by the ultrasonic module, the system goes out of range by displaying an error message, OOR (Out-of-Range) on the LCD. Therefore, this device can be of great importance for applications in areas like fuel storage, providing flood warnings and simple water level control in homes just to mention a few.

Key words: Microcontroller, ultrasonic, fluid level, measurement, system