FORCED DRAFT UNIT Advantages Better accessibility y of mechanical components p for maintenance Slightly lower horsepower since fan is in cold air. i (Horsepower (H varies i directly di l as the h absolute b l temperature) Less Vibration because of isolated support for mechanical equipment Bundle are easy to remove for major repair lower capital cost. Tube Bundle Fan Drive Details • Direct Drive • Forced Forced-Draft Draft Belt Drive Typical Extended Surface Tubes Which standards are used for AirAir Cooled Exchangers? First, almost all air coolers are built to Sect. VIII, Division 1 of the ASME Code, since they are pressure vessels API661 standard for air-cooled heat exchangers TEMA (T (Tubular b l E Exchangers h M Manufacturing f t i Association) HTRI (Heat Transfer Research Institute) Air Coolers Temperature Control The combination of adjustable shutters with variable speed p drive or with controllable fan pitch is frequently used for close fluid temp control. Thi system is This i particularly i l l useful during start-up or shutdown where fluids are subject to freezing in cold ambient temps. It is well adapted to fluid temp control under high wind and freezing conditions.