Automation in the control of a water mixer used for sanitation of bovine milking unit

The milking unit sanitization is necessary after use. The processes are usually divided in steps and each one needs water at different temperatures for proper cleaning. However, to get the right temperature for each step cannot be easily achieved manually in rural properties. A hot water and cold water flow are needed. The farmer will need to properly mix the two water flows in order to reach a desired temperature for the cleaning step, and due to temperature fluctuations and flow, a constant intervention is necessary to maintain the same optimal temperature of the mixture. In this work, a mixer with automatic control of cold water flow, coupled to an electric heating system, was developed with the aim of reaching an ideal final temperature required for the sanitation of milking units, regardless of temperature variations and flow at the entrance. Two control boards were compared, the Arduino and the IOIO during the first seconds of operation of the system, the opening angle of the cold water registered is calculated from the hot and cold temperatures. After this gradual adjust in the angle was performed. The temperature was considered to be attained when it reached a maximum deviation of 1°C relative to the desired temperature. The system proved to be slightly more satisfactory with the IOIO, since the desired temperature was stabilized at lower average time, 24 s after system initialization.