Heater Catalog - Watlow

Air HeatersDuct HeatersLDH SERIES and D SERIESPressure Drop vs. Air VelocityThe rate at which pressure drops through the duct heateris critical for properly sizing blowers and pumps. ThePressure Drop vs. Air Velocity graph gives recommendedmaximum velocities in feet per minute and meters perminute according to the air velocity and duct heater size.To determine the pressure drop through the duct heater,follow the air velocity (FPM or MPM) over to theappropriate curve, which identifies the duct heatersize. Then, take the intersecting point down to theapproximate pressure drop value.Air Flow for ≥ 24kWThermowell6kW9kW12kW18kWAir flow for6 to 18kW>18kWNote: Viewing from the element ends—therecommended air flow direction throughelement bundle changes at >18kW.Air Velocity—FPM20001900180017001600150014001300120011001000900800700600500400300200100Round Tubular Duct Heater D6Round and FIREBAR Tubular Duct HeatersPressure Drop vs. Air VelocityRound Tubular Duct Heater D12Round Tubular Duct Heater D18Round Tubular Duct Heater D24 - D125®FIREBAR Duct Heater of Equivalent kW is 30%the Pressure Drop of a Round Tubular Duct Heater 1Air Velocity—MPM80075070065060055050045040035030025020015010050Round and FIREBAR Tubular Duct HeatersPressure Drop vs. Air VelocityRound Tubular Duct Heater D6Round Tubular Duct Heater D12Round Tubular Duct Heater D18Round Tubular Duct Heater D24 - D125®FIREBAR Duct Heater of Equivalent kW is 30%the Pressure Drop of a Round Tubular Duct Heater 10.020.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20Approximate Pressure Drop—Inches of Water0.0050.010 0.015 0.020 0.025 0.030 0.035 0.040 0.045 0.050Approximate Pressure Drop—Kilopascals1 FIREBAR ® flat tubular element duct heaters are available as extended capabilities to enhance your application output or performance. Although ductheaters are not normally constructed with FIREBAR elements, the pressure drop reduction using FIREBAR as a distinct advantage is shown above.OptionsWattages/VoltagesTo meet specific application needs, voltage and wattagecombinations outside stock product parametersare available.For more information about this option, contact yourWatlow representative.394 WATLOW ®