Heater Catalog - Watlow

Tubular HeatersFINBAR Single-Ended HeatersAir HeatingThe Watt Density, Air Flow and Sheath Temperaturegraph shows the relationship between watt density, airflow velocity and sheath temperature, along with arecommended temperature to avoid deteriorating thefins. Be aware that lower sheath temperature yieldslonger heater life.The graphic representation is based on a single-endedFINBAR, various air velocities (at 68°F/20°C inlettemperature) and different watt densities.Watt Density, Air Flow and Sheath Temperature (°F)To determine, from the graph, the operating temperatureof the FINBAR’s sheath, identify the air velocity curve thatapproximates your application in feet per second (metersper second). Then, look at the vertical line that mostclosely approximates the FINBAR’s watt density. Fromthe intersecting point, read over to the temperaturecolumn to determine the sheath’s operating temperature.Watt Density, Air Flow and Sheath Temperature (°C)1600Air Flow1000Air Flow14001 FPS900Sheath Temperature—°F12001000800600400Max. Heater TemperatureMax. Heater Temperatureto Avoid Scaling of Fins4 FPS9 FPS16 FPS20 FPSSheath Temperature—°C800700600500400300200Max. Heater TemperatureMax. Heater Temperatureto Avoid Scaling of Fins0.3 MPS1.2 MPS2.7 MPS4.9 MPS6.1 MPS2001005 10 15 20 25 30 35 40 45 50 55 60Watt Density—W/in 21 2 3 4 5 6 7 8 9 10Watt Density—W/cm 2Dual Ended FINBARFINBAR elements are typically terminated at one end.Upon request, however, dual-ended FINBAR heaterscan be ordered. To order, specify dual-endedFINBAR and lead length.Application Hints• Avoid deteriorating the fins by not exceeding therecommended maximum fin temperature of1100°F (600°C).• Ensure proper air flow to prevent prematureheater failure.• Locate the temperature sensor downstream fromheater(s) for process temperature sensing.The following mounting parameters are recommended:• Air flow over element must be parallel with theflat side. Air Flow Relat Temp• Element center line to element center line spacingmust be a minimum of 1 1 /2 in. (38 mm).TemperatureSensorProper air flow relative to the heater’ssheath is parallel with the longer crosssectional axis.WATLOW ®113