Equipped with a complete ventilation system, there are no structural dead corners inside the motor that may affect ventilation. 
The shell and pipeline are made of non combustible materials and have sufficient mechanical strength. 
Maintain sufficient positive pressure inside the casing and main pipeline relative to the external atmosphere. 
The motor must have safety protection devices (such as time relays and flow monitors) to ensure sufficient ventilation, and must also have automatic protection or alarm devices for under pressure in the casing. 
The quick opening door or cover on the shell must have a device that interlocks with the power supply.