A fan is a historical machine (still in use) which is used to create a flow within a fluid. This fluid is usually a gas such as air. These machines namely fans consist of a rotating arrangement comprised of vanes or blades. These vanes or blades act on the fluid or the gas. This rotating system or assembly of blades and the hub is collectively known as a rotor.
These fans produce flow in the air my manipulating high volume and low-pressure system. These work in a way opposite to compressors, which are used to produce high pressures at a comparatively low volume of fluid.
The “punkah” was a sort of fan that was used in India since about 500 BCE. This device was a handheld fan which was made from bamboo strips or in some cases other plant fibre and which could be rotated to move or swirl air in a definite direction. During British rule, there used to be large flats fans which would be fixed to the ceilings and to make them work they would be pulled by a servant.
If we look at the blades of a fan then we see a problem which is very common and a recent headache in terms of cleaning. There is always some dust accumulated on a fan because of many reasons. They are:
- When the blades rotate they pass through the air which has many constituents like dust particles, suspended particulate matter and a few others. When the blade cuts through the air these suspended particles collide with it and unlike the air particles these particles which are very small, don’t bounce off and they stick to the surface of the blades. This creates the first layering of the dust particles which is not seen that much as the dust particles are microscopic in nature. After this the dust particles at a microscopic level have grooves and microscopic pits on the first surface accumulated and thus when this keeps on rotating then these few slightly larger particles get attached when they collide and they stay there due the fact that they have slightly become oriented in that space and are held by weak adhesive forces between the other dust particles.
- When the blades cut through air they develop charges which accumulate at the edges and these attract the dust particles by induction and by attraction, the particles stick to the surface of the blades. Then in the similar way as mentioned above this forms the first layer and when the fan keeps on revolving then these dust particles in the deposited layer due to friction loose electrons and become charged and they then induce charge on the other suspended dust particles and in the similar way keep on increasing the volume of dust sticking to the surface of the blade all the while other than the charge the volume also increases by the method mentioned above.
In both these cases the dust articles combine with the moisture in the air and it sort of forms a bond that sticks tightly to the surface of the blades and is not easily removed by simple tapping or at times with even cleaning with a dry cloth. To remove the stuck dust in such cases there is a need of cleaning with a wet cloth or may be washing. It is advisable to clean your ceiling fans regularly, especially if the blade size of your fans is more. Such fans are considered as the best fans for summer, but also require enough attention and maintenance.