Why do most "fan blades" have three numbers?

Why do most "fan blades" have three numbers?

Why do most "fan blades" have three numbers?

Fan number 1

Vibration or sound is above all, speed is above all. The wind is low. Example Mobile's vibrator.

Fan number 2

The wind is the highest and sharpest, as a result the wind can go far. Speed, vibration and noise are a bit lower than before. Examples are any high speed fans that are used especially in the event house.

Fan number 3

Air is moderate. Sharpness is moderate. Vibration, speed and sound are full and less than the previous two. Examples of this are unnecessary. But it is very economical and efficient according to the weather conditions of our subcontinent.

Fan number 4

The air is low but sweet. The sharpness is very low. Vibration speed and noise are very low. Generally more common in colder countries, now many people love to run the fan with air conditioning. Such a fan is suitable there. Setting the AC to a certain economic temperature and running the fan lowers the electric bill. So let's say this fan is not as economical or efficient for us In temperate countries.