The FN Series Electric Box Furnaces feature extremely uniform temperature gradients over a wide temperature range, and atmosphere tight construction. Two uniformity ranges are offered: ±10°F (±5°C) and ±°F (±°C). Several important features are combined to achieve uniformity within the defined work zone. These features are uniform distribution of elements, fan circulation of furnace atmosphere, all ceramic fiber insulation, six zones of element control, SCR power control, generous extra area inside the furnace for air circulation and to keep direct radiation of elements at a minimum, and a very tight gasketed and interlocked door seal. Atmospheres may be air, inert or combustible. The uniformity specification is guaranteed from 300°F (150°C) to the maximum temperature of the furnace. The maximum temperature rating depends on the type of fan used, type of elements, and grade of insulation. Three temperature ranges are offered: 1800°F (980°C), 2000°F (1095°C), and 2200°F (1200°C). These furnaces are ideal for aviation work or any critical heat treating that requires certifiable uniformity. The design details are carefully thought out for convenience of use, service and flexibility. See just how good the uniformity of the FN Series furnace: Look at a PDF of an actual uniformity test.