Heater Catalog - Watlow

High-Temperature HeatersCeramic Fiber HeatersPerformance DataPerformance CapabilitiesThe Performance graph shown below representscapabilities of the five heater element configurations.The curves compare upper temperature limits versuspermissible design watt densities to achieve a standardheater life expectation of 2,000 hours.As with all Watlow heaters, the major application concernis the heater’s surface watt density as it relates tothe application temperature, such as with the furnacechamber temperature or the radiant surface temperature.When evaluating an application for temperature andwatt density requirements, it should fall to the left of andbelow the performance limit lines. If the application fallsinto this area, then it is in the safe performance area.The further into this safe performance area, the higher thelife expectancy of the heater. If an application requirestemperatures or watt densities that fall into the area to theright of and above the lines, then the application operatesbeyond the heater’s typical design or performancelimits. Using a heater required to perform in this areaof the graph may result in a shorter life expectancy.For information specific to an application, contactyour Watlow representative.General Guidelines: Upper Limit Lines for Heater Performancevs. Maximum Application TemperaturesHot Face Surface Watt Density—W/cm 2Furnace Chamber or Load Temperature—°F2400220020001800160014001200100001.0 2.0 3.0 4.0 5.0 6.0Beyond Design/Performance LimitsSTCoilEmbedded SinuatedEmbedded V-SinuatedExposed SinuatedExposed V-SinuatedSafe Performance Area"Black Body" Radiant Temperature2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 381300120011001000900800700600Furnace Chamber or Load Temperature—°CHot Face Surface Watt Density—W/in 2436 WATLOW ®