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Alternate shapes for compressed cylinders

  1. Apr 7, 2014 #1
    Good Morning everyone..

    Has there been discussion on here regarding alternate shapes for compressed air cylinders (+3000 psi) I know why compressed cylinder are the shape they are, but in this day and age of science & technology, why are we still using round cylinders? could one not design a flat vessel (with slightly rounded edges) ?? just a thought...
  2. jcsd
  3. Apr 7, 2014 #2


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    Well, not everything can be improved by changing the shape. Wheels are still round after eons of use. Why not try a different shape besides circular? Who cares if the ride gets a little bumpy.

    Heavy duty cylinders have to withstand not only the high pressure of the contents, but they must also be durable and capable of taking a fair amount of rough handling when they get moved from place to place.

    If you were to fabricate a vessel which was not circular in cross section intended for high pressure storage, you would find that these shapes are not very easy to fabricate in the thickness of material required for the pressure. Being non-circular, it would probably be difficult to move these vessels any distance without using some kind of dolly or other device. With a cylinder, all you have to do is rock it on the edge of the bottom and roll it to wherever you want to go: you don't have to lift the entire cylinder.

    Gas bottles have retained their cylindrical shape throughout the years because they still can do the job at an economical cost and are relatively simple to fabricate.
  4. Apr 7, 2014 #3
    Because for the vast majority of applications, weight and/or cost is also a prime factor. Cost is related to the amount of material used in the tank and its processing cost. The lowest weight format for any pressure vessel is a sphere, which is why these are used in weight sensitive aircraft or spacecraft applications. However, often a sphere is not the right form factor for other reasons, and a cylinder is used, often with hemispherical end-caps (next best option). Any other shapes would increase the weight substantially, especially at high pressures. You will need to research stresses in metals (or composites) to learn why a sphere is the lowest mass solution for internal (or external) pressures.
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