Barrel Heaters - Hasmak.com.tr

W A T L O W<strong>Heaters</strong>MI StripApplications andTechnical DataCalculating Watt DensityWatt density is the amount ofwattage per square inch of heatedarea. To determine watt density,divide the total wattage by theheated area.Watt Density =Total WattsHeated AreaTo apply this equation we mustdefine the term “heated area.”Heated area is the total contactsurface of the heater less areas ofno heat that are found aroundterminals, mounting holes, etc.Heated Area =Total Contact Area - No-Heat AreaTo calculate the heated area:1.Locate the no-heat factor fromthe chart on the right thatcorresponds to the type of heaterbeing considered.2.To use the formula below, insertthe no heat factors, length andwidth (in inches).Heated Area =(Length - No-Heat Factor)x WidthTypeFactor(in.)1 in. wide post term 1 on 1 (1.56)1 in. wide post term 1 on 1with mounting holes (3.56)1 in. wide post term 2 on 1 (1.93)1 in. wide post term 2 on 1with mounting holes (3.93)For all other widths:2 on 1 post terminal (1.18)2 on 1 with mounting holes (3.18)Calculating Watt DensityThe sketches on the next page andthe graph on this page will helpselect the correct watt density for aparticular application. First, refer tothe sketches to determine theheated area of the heater. Then, usethe watt density formula and graphto make sure that the maximum wattdensity of the heater will not beexceeded in the specific application.Watt Density =WattageHeated AreaNote: Derate maximum allowable watt density by 50 percent when usingmounting holes only for clamping.Maximum Allowable Watt DensityPart Temperature—°F12001000800600400200Watt Density—W/cm 25 10 15 20 2530MI strip clamped to a good heat sink,operating in 21°C (70°C) ambient airMI strip clamped to a good heat sink,operating in insulated or enclosedenvironments600500400300200100Part Temperature—°CThermoforming<strong>Heaters</strong>40 80 120 160 200Watt Density—W/in 2315