tubular heating element / ceramic
The low mass of the heater makes them the perfect choice where high temperatures are needed quickly.
Keith Company manufactures wire wound (aka coil resistance wire) heating elements that work best for air velocities of 5 to 2,000 SFPM. Higher air velocities could cause the coils to touch each other and short out, so tubular air heaters may have to be considered. A successful installation of air heating elements consists of the heater itself, an airflow switch which turns off the power to the heating element if air flow is outside the specs, a high limit temperature controller installed close to the heating element and the process temperature sensor at the right location in the air stream. Wire wound heating elements are made from resistance wires like Nichrome 80/20, Kanthal A1, APM and others and fixed onto a supporting ceramic or porcelain element. We recommend solid state relays or SCRs for power control for this low mass heaters.
The low pressure drop due to the large open space makes open coil heating elements the best choice for applications where large air volumes need to be moved. (example: convection ovens)
We don't recommend wire wound heating elements for glass applications because they can be the number one cause of contamination because of oxidation at high temperatures. Expansion and contraction of the heating wire causes small oxidized particles to be ejected into the work space.