Fame-proof / Explosion-proof motors are designed to keep explosions contained within a sealed environment and cool the escaping gases so that they don’t ignite surrounding materials in the atmosphere. Flameproof motors are designed to withstand the pressure caused by an internal explosion without incurring any damage and are also able to prevent flame propagation outside.
They are required to ensure to provide insurance if the motors are not used where it is required. safety and to avoid fire hazards. Insurance companies may refuse.
The main difference between a flame-proof motor and a normal is the construction of the ‘Frame of the motor’ and ‘Terminal box’. The frame is more robust with larger spigots and end covers on the bearing housing. This more robust frame is needed to contain if any gas explosion (not an electrical explosion) occurs inside the frame. The larger spigots on the frame (called flame path) also act as a cooler for the flames so as to cool down the escaping gases.
As per the Indian standards the explosive gases are classified under two broad categories viz
The flame-proof motors mandatorily need to be certified by third-party agencies depending on the type of industry and location of use. Some examples of these agencies are: