How to use mica band heater and how does a cartridge heater work
band heaters
Loss Prevention for Band Heaters
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Sidebar: Understanding Watt Density Calculations
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The watt density should be selected in accordance with the operating temperature.
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To avoid short cycling and inefficient operation, select a wattage as close to the needed capacity as possible.
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The wattage should be in accordance with the voltage and current rating of the controls.
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The safe heating pattern,and heating elelment of the material heated, thermal conductivity and coefficient of expansion of the cylinder are other factors that should be taken into consideration while deciding wattage.
A cartridge heater is a tube-shaped, industrial heating element that can be inserted into drilled holes. Cartridge heaters provide localized and precise heating and are commonly used in the heating process industry. Typically, cartridge heaters are used to heat a metal block from the inside and can be custom manufactured to a specific watt density based on the requirements of the application.Cartridge heaters are most frequently used for heating metal parts by insertion into drilled holes. For easy installation, the heaters are made slightly undersize relative to their nominal diameter.
How does a Cartridge Heater work?
A cartridge heater consists of resistance coil wound around a ceramic core that is surround by dielectric and encased in a metal sheath. Powered heat transferred through the coil to the sheath causes the sheath to heat up. This heat is then transferred to the inside metal part requiring heat.To fit a cartridge heater in a low or medium temperature application (600°F or less), general purpose drills are usually adequate for drilling holes. Holes can be drilled .003” to .008” over the nominal size of the drill, resulting in fits of .009” to .014.” While this fit is slightly looser than would permit optimal heat transfer, it aids in the installation and removal of the cartridge heaters with heating cable, especially those with long sheaths. At high watt densities, a close fit is much more important. The holes should be drilled and reamed rather than just drilled with a general purpose bit. With a tighter fit, the heater will run cooler and have a longer life expectancy.
