Emergency smoke exhaust concerns life and property safety. There are certainly some governing standards for the design and performance requirements.
How can one fan be more resistant to high temperatures than another one? According to the material types that comprise the fan, parts and volume characteristics, there is a highest operating temperature that is recommended for each model. For the limiting temperature, it is the temperature that fan components will get to in operation. The highest temperature is supposed to be the lowest value beyond the withstanding ability of one component. For instance, the bearings perhaps are the component that has limiting temperature and the wheel is the limiting component in other cases.
When the high-temperature application is considered, the material is perhaps the most significant factor to see. Generally, the highest temperature aluminum can withstand is 250ºF, 750ºF for standard carbon steel and 1000ºF for 316 stainless steel. For critical components of fan, ferrous materials are used for higher temperatures.
To meet the requirements of high temperature applications, the often used method is to have separate categories according to the vendor requirements on temperature and time. If the customer determines to choose higher temperature option than what is needed for safe operation, it may incur additional investments and more costs are caused.
Bearing lubricant is also an important factor. There is always a long list of lubricants to choose from for various applications. The right lubricant will help sustain bearing life. What is more, construction modifications can be made to the bearing in the design stage to withstand high temperatures, for example making a bigger cavity for more lubricant to be held in.
An important thing to know about emergency smoke exhaust fans is that they are in a design to run efficiently in a predefined temperature and time range when there is a continuous power supply to the fan. Emergency smoke exhaust fans are not supposed to withstand high temperature for continuous operation. If exposed to exceedingly high temperature of smoke of fumes, parts or components of the fan may be damaged beyond the time limit. And the result is the fan get faulty and unable to operate in the future.