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Re: [Phys-L] Bourdon tube foundations



On 10/26/2012 08:56 AM, Roberto Carabajal wrote:
Please, I would appreciate a link to a detailed description of the Bourdon
tube gauge pressure operation, because in general what I have founded show
the final formula but not the foundations including Hooke`s and Young`s
laws.

It's interesting, and not entirely obvious. It will take me
a while to write up even the beginnings of an answer, and I
don't have much time right now.

In the meantime, here are some hints:
*) The Bourdon tube is often described as a curled-up tube.
Have you ever noticed that in practice, the tube is not
particularly round? It's a tube that has been flattened
and then rolled up.

*) Once upon a time in the physics lab there was a wager.
Some people bet one way, and some the other:
a) It should be possible to build Nodruob tube, i.e. a
backwards Bourdon tube, i.e. a tube that would become
*more* curled-up if you put pressure into it.
b) This is not possible. The tube *must* straighten
out if you put pressure into it. This assumes constant
external ambient pressure and other reasonable ordinary
conditions.

Which way would you bet?