Cooling towers are utilized to reject excess heat from manufacturing processes. Depending on the manufacturing process application, cooling towers can either be closed circuit or open circuit systems. Closed circuit systems rely solely on airflow to cool the water stream or thermal heat transfer fluid stream. Open circuit systems rely on evaporation to release heat into the atmosphere. Airflow is determined by the type of cooling tower as well. In natural draft towers, cooling is dependant upon on natural airflow to cool the water stream. In mechanical or induced draft towers, cooling is dependant on fans to circulate air.