This ventilator is used mostly in warehouses where fires can heat the air to 1000 degrees F. Nearly every fan on the market today offers the ability to operate in air that hot for just 15 minutes.

This new Invisco design incorporates a very strong heat barrier, calcium silicate, to block heat from the blade and shaft from being carried by the motor shaft into the motor. There are 2 shafts, the motor shaft and a shaft in the blade. They are connected by strong flanges that are bolted to the calcium silicate.

This shows how the calcium silicate will block heat from the blade to protect the motor.

The second heat blocker is a shield around the motor that forces the hot air to flow past the motor while the motor is bathed in cool air pulled into the shield from outside the air shaft.

Here is an artist conception of that design.

This does not show the calcium silicate heat blocker