Information on hot air heaters energized without airflow
The following figure shows the relationship between the load on and temperature of the heating element when energized without any air flow. An average air heater is designed with a surface load of approx. 11 W/cm 2. The temperature can reach 2552ºF (1400ºC) or above for those with metal cases. At this temperature it will burn-out within a very short time (possibly in few minutes).
Click here for air heater models and designed surface load. (Opens in a new window, close the screen to return)
The “Estimated service life of heating element” shown in the figure below is for an electric heating wire with a large diameter but smaller diameter wires can break abruptly if the temperature exceeds 2372ºF (1300ºC).
The surface load has to be reduced to below 7 W/cm2 to have sufficient withstand ability when energized without air flow. Therefore, if the size of the heating element is the same as usual products means that only 60% of the power can be used. To obtain the same power, the size has to be increased by 50% or more.
When energized without air flow, and withstand ability is required to only a certain extent, then 8 to 9 W/cm2 is designated as an intermediate surface load.
* While using normal products, take sufficient care and ensure that the products are not energized without air-flow.