Hot filling lines process non-carbonated beverages such as fruit juice, nectar, soft drinks, isotonic drinks, and tea. The beverage is heated to a controlled temperature before filling, then transferred into heat-resistant bottles and cooled in a multi-stage water-spray tunnel. Since temperature fluctuations can leave heat-resistant microorganisms untreated, while excessive heat may deform the bottles or damage the flavor and nutrients of the beverage, the lines continuously monitor the filling temperature. When the temperature is not within the set range, a PLC-controlled three-way valve sends the beverage back for reheating instead of allowing it to enter the filling section. Once the correct temperature is restored, the filling process resumes and the bottles move directly into the cooling tunnel, which shortens their exposure to heat.