| Special Mica Barrel and Nozzle Applications and Technical Data Operating Factors Use as a low watt density rating as the application permits. A close match of the heat supplied to the actual requirements will reduce temperature overshoot, reduce cycling and increase the life of any band heater used. for the heater using: Heated Area x Maximum Watt Density Calculate the heated area of the band heater by subtracting the no-heat area from the total area in contact with the cylinder (3.14 x I.D. x width). Subtract the no-heat area at the terminals (from table) and any additional no-heat area caused by holes, slots or oversize gaps. Determine the maximum watt density of the heater from the graph on this page. The curves are based on narrow heaters mounted on a smooth, steel cylinder. Apply the necessary correction factors: • For heaters 2X inches (57 mm) to five inches wide (127 mm), multiply watt density by 0.8. • For high expansion cylinders (aluminum or brass), reduce the watt density by 3 W/in2 (0.46 W/cm2). • For heaters 2X inches to 5 inches wide installed on a high expansion cylinder, reduce watt density by a total of 3 W/in2 (0.46 W/cm2) only. • For regular cylinder surfaces other than smooth, machined finish, reduce watt density by 3 W/in2 (0.46 W/cm2). • For heaters that will be insulated or enclosed, contact Watlow for specific watt densities. |