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

[Dan h <machine@epix.net>]

But it's not pressure that is detected this way.
To use this method properly to detect the end of the elastic limit
on a sub hull,
you read the volume of fluid expelled from the interior of the sub
as the sub is being squeezed in the test chamber.  They are related,
but it's easy to detect very minor changes in the subs over all volume
using this method.  Accuracy is a matter of the diameter of the vessel
your reading the expelled fluid in.  For only a few thousants of an
inch reduction is the sub's diameter there is a great difference in the
fluid level in a small graduated tube.  When monitoring pressure with
in the sub, the pressure gauge only reads the pressure of the chamber. 
It's one in the same!  Some fluid must be allowed to escape from the
interior of the hull to allow the sub to compress or your not actually
putting forces on the hull.

From what I read, this method was used by Perry Submarine Company in Florida at one time.

Dan H.
AndrePevestorf@aol.com wrote:

In einer eMail vom 13.04.2002 02:00:07 (MEZ) - Mitteleurop. Sommerze schreibt machine@epix.net:
 
 

When your plot starts ot go nonlinear, your at the end of the elastic limit.  No computer necessary.  Reading fluid rather than air, you got an exact easy reading. Dan H.

You are right Dan. For a test in a chamber this is the easy way.
But I was thought about to use this method together with a deep sink test outdoor in the sea ...
and then you will not be secured from thermoclines (as Alec mentioned) and it´s not easy to control a equal sink if the sub is on a roop and there is some rough sea .. (OK, you will wait for calm to to that test..)

A computer is not absolutely necessary to track the curves but sitting all the days in front of a screen makes a little bit lazy and if the computer can make the job... he should do it...
even if you get the signals from the sensors as a appropriate current between 4...20 mA (as it is usual for pressure indicators)

A.