How come ceiling fans get so dirty when they are in constant motion?

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   mary615posted 9 years ago

   How come ceiling fans get so dirty when they are in constant motion?

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   Noumanfaizposted 9 years ago

   because when the fan pulls down dirty air the wings of fan remove some dust because of their fast moving a circular sheet like wind stream is formed that moves the dirt in the inner side. This process takes a lot of time like weeks ,couple fo weeks ,months and sometimes even years.

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   ARUN KANTIposted 9 years ago

   The blades of ceiling fans in motion  gather a layer of dust which  then they can broadcast  if they’re not cleaned regularly. So  it is important to turn the fans off long enough to clean the blades off and on.

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   KenDeanAgudoposted 9 years ago

   It is because even in constant motion, dust and particulate matters on the air stick on the fan especially if it get moist or wet. In some cases, dust on ceiling fan are cause by dirty substance on the air just like our nose, even how hard we tried to make it clean and away from dirt, we find our nose still have booger! lol

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5. 97

   eugbugposted 9 years ago

   Some dust or particulate matter has a degree of stickiness which makes it stick to the fan. e.g. oils from cooking, tar from  smoke etc. Also static cling will make dust stick to fans. Possibly as a fan spins through the air,  friction with air molecules increases the charge on the blades if they are made from plastic. Once a layer of dust builds up, more dust can stick to the "rough" surface.

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      tsmogposted 9 years agoin reply to this

      Great work! As said I just ponder. However I enjoy fun. http://www.spaceflight.esa.int/impress/text/education or Impress Education (ESA): Circular Motion where the formulas for mass of rotating objects are shared. Again, I don't understand this stuff

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   tsmogposted 9 years ago

   Speculatively it is the 'venturi' effect of air flow. The fan does cause a draw downward pulling air toward the rotating blades. Like a carburetor on a car (even a fuel injection system with air intake) particles or residue will also be pulled downward with the air flow.
   
   Air is a mixture and is not pure in any real sense. Air is composed of oxygen, nitrogen, argon, carbon dioxide, and about a dozen more elements. Each have different properties. Then there is dust and its compostion(s) - smoke from cooking, dust from day to day, outside influences if windows are open, and etc.
   
   The fan spins, yes, but it has a surface area and it spins at a constant rate. All surfaces have tension factors with elements it is in contact with. Each has different surface tensions. For instance smoke is probably higher than dust as it is more closer to a liquid than dust being somewhat dry. So, a fan near the kitchen may get 'dustier or dirty' more than a fan in the bedroom.
   
   There are other factors if one gets down to the nitty-gritty of it all. There is also the affects of gravity. Gravity is the attraction of one mass toward a greater mass. Dust and smoke for instance have less mass than the fan blades even though they are spinning. Just like meteors are attracted toward earth even though the earth spins around the sun and around in the universe.
   
   When all those are combined a percentage mostly likely very small will accumulate upon the fan blades. They may, and not being a scientist, so this is speculative follow these principals having the greatest consequences resulting with accumulation.
   
   Venturi effect → gravity → compound or element structure (smoke contrast dust) → surface tension principals → down time (the fan stops and the compound/element sits inactively)
   
   I say down time because just like a pond that grows stagnant with less activity (air flow around the fan blades like a stream entering the pond, passing through the pond, and exiting the pond) the accumulated matter - dust particles, smoke residue, and etc seeks a state of entropy (gradual decline toward disorder regarding energy) or does nothing and sits on the blades. Then in a sense it forms a 'new' compound of all those elements - smoke, dust, and etc we may call 'gunk' or 'grime' through the properties and principals of attraction(s) like gravity.
   
   It is nature at work with the rules we know nature works within.

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      eugbugposted 9 years agoin reply to this

      It would be interesting to do the math to see what influence gravity due to the fan blades mass would have on the downward trajectory of a dust particle. I would think  Earth's gravity would be dominant, and a particle would be deflected minutely.

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      tsmogposted 9 years agoin reply to this

      I am much more concept orientated than math. Distance I am sure will come into play with regard to mass and attraction as when a force is more dominate regarding vector angles. Again, I am more conceptual. Kinda like the movie 'Armageddon' Thanks!

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      mary615posted 9 years agoin reply to this

      What a great answer!  I leave my fans on all the time, and of course the kitchen fan gets dirtier than the others.  I tried apply paste wax to them, but it didn't help.

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      eugbugposted 9 years agoin reply to this

      For any nerds out there interested in such trivia, I just did the math. It turns out that a 50 kg mass at 10 cm distance would accelerate a 1 microgram piece of dust to walking speed in 7 weeks! (Using F=Gm1m2/r^2)

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      tsmogposted 9 years agoin reply to this

      LOL, LOL, LOL The solution set is Fantastic and paper towels

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   agusfananiposted 9 years ago

   Static electric also one of the factors  to make dirt sticks on plastic fan blades.

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