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I Blower for linear air track

  1. Nov 30, 2016 #1
    I am a Physics teacher. I made a linear track of length 2m with 400 holes(two rows of 1mm dia). Somewhere I read household vacuum cleaner can be used as a blower. But it does not create sufficient pressure to lift the cart. What should be the specifications of the blower which can be used? Any suggestions for mass and material of the cart? I am using cart made of aluminium. Sakthivel, Coimbatore, India.
     
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  3. Nov 30, 2016 #2

    ZapperZ

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    You neglected to describe the nature of the cart, how heavy it is, its surface that will hover over the track, etc....etc.

    Zz.
     
  4. Nov 30, 2016 #3

    sophiecentaur

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    I assume you have used the V construction that's used in commercially available tracks.
    The quality of construction can make a huge difference to the performance of an air track. The flatter the two surfaces (track and cart), the less volume flow of air is needed. The pressure and flow are dictated by the total load and area (probably a √2 factor in there) and the volume flow is dictated by the gap round the edge of the cart and the gap needs to be greater than any undulations / high spots on the surfaces.
    Then there will be the other unused holes that need to be supplied even when they are not covered by the cart.
    I can only speak from experience of a system that the school had when I joined. The track was very sticky and unimpressive with the old cylinder vacuum cleaner that they had. I bought a special air blower, from the equipment supplier (Griffin? perhaps), and the whole thing worked better. The cart would go from end to end several times as it hit the rubber band buffers each end.
    I could suggest the sort of blower that's supplied for bouncy castles. I see them on eBay. 450W blower for around 40GBP. Worth considering - once you are sure of the quality of your track.
    Google "Air track demonstration" and see what's available to buy. I found a glider of mass 170g
     
  5. Dec 1, 2016 #4
    I have used iron pipe of square cross section 2" for the air track. The glider of mass 100g is made of an aluminium L angle of size 1.5" and thickness 2.8mm. Length of the glider is 18cm. The area of the glider in contact with the pressurised air is 126sqcm. I could make the glider float using a compressor in the mechanical engineering lab. But I want a small and cheaper blower which I can be used in the physics lab. Sakthivel
     
  6. Dec 1, 2016 #5

    sophiecentaur

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    That size is a bit smaller than I remember for the one at my School but comparable. I presume you use it in a 'vee' orientation.
    How accurate are the dimensions? (Flatness and uniformity etc) Using a moulding medium, squashed between the two surfaces, you could measure the variation in gap size and you could reduce high areas with some grinding medium, if necessary. Square section iron tube may not be made to a very high spec so it could probably benefit from some time spent on improving it. Aluminium Extrusion may be a bit better. That would be quite important if you are trying to minimise the spec for the blower. It would not be difficult to measure the pressure (a water-filled manometer) and the volume flow (time to fill a large plastic bag).
    If you want a good answer from PF (good enough to contribute to the success of the project and to avoid a lot of suck it and see) you will need to do some measurements.
    I wouldn't think that you could get a cheaper blower than 40GBP for bouncy castle inflation. A cylinder vacuum cleaner is not actually designed with 'blowing' in mind so it could be poor value.
     
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