Williams & Davis Thermal Fluid Heaters utilize a 2 or 3-pass design allowing for high fluid velocities and low film temperatures. The heaters are available from 2,400,000 BTU/hr to 50,000,000 BTU/hr output and maximum operating temperatures to 750°F (340°C) . Heaters are built and tested in accordance with ASME Code Section I or ASME Code Section VIII, Div. 1. Thermal fluid ("hot oil") heating systems are used in many industrial applications where efficiency and accurate temperature control between 300°F and 750°F are required.