Re: [PSUBS-MAILIST] Isn't 'Mini book review.' anymore--pressure test

[AndrePevestorf@aol.com]

In einer eMail vom 12.04.2002 21:29:17 (MEZ) - Mitteleurop. Sommerze schreibt SFreihof@aol.com:


> From: Alec Smyth <Asmyth@changepoint.com
> snip>>
> I'm getting into an area here that I don't know much about. But no, I'm not talking about a stress gauge. I'm referring to a thin tube that allows you to track air flow out of the hull as the hull compresses. I have not seen this done, but I've read somewhere that's how they do it. 
> <<snip
>
>
> This sounds very similar to the method used for hydrostatic testing of scuba cylinders.  The scuba tank is filled with water and placed in a water-filled pressure chamber.  Water is used so if the scuba tank ruptures, it will not explode because water is not compressible.  As pressure is applied into the scuba cylinder, the scuba tank will expand and displace water in the test chamber.  This displaced water rises in a tube and is used to gauge the expansion of the scuba tank under pressure.  What you're referring to is a method to conversely gauge the compression of the pressure hull.  Sounds like a good idea to me.
>
> Stan
> 2 man Ambient Dry
> Ft. Lauderdale


Hi Stan,

But the remaining problem is that for a scuba tank you know (or can relatively easy calculate) the exact allowed linear elastic deformations and this gives you the exact permissible change of the tank volumen. So you only have to look that the watercolumn in the tube does not rise over a define value... (depends only from the tank dimensions and the material while the shape is standard) 
Will say if the product is standard than you have to check only a define value..
But if the stuff is unique (like a psub should be -hehe) than you have to analyse the differential changes because you donīt know the absolute values...and all the problems with thermoclines for example are in the boat again...

A.