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

[ronleonard <ronleonard@shaw.ca>]

This is not a trivial exercise. Just the weight of the water alone will
put great pressure on the bottom ring of the tank, never mind once you
pressurize the tank. A better solution would be to dig a hole to put the
tank in and back-fill it with concrete.


-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Thijs
Struijs
Sent: April 11, 2002 5:37 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Isn't 'Mini book review.' anymore--pressure
test


I agree on John.  Water is not compressible. This means that in the case
of a rapture it doesn't expand (=explode) either. I would even suggest
to partly fill the sub itself with water. Whatever you do, I would put
the tank in the open field and dig a big hole to hide in.

Making the tank cannot be to difficult. There are many companies making
tank for internal pressure. Take one of these, cut him in halfs, weld
two big flanges to the two halfs and bold them together. A professinal
can probably make the calculations in a view minutes.

Greetings,

Thijs Struijs


----- Original Message -----
From: "John Brownlee" <jonnie@scarymonsters.net>
To: <personal_submersibles@psubs.org>
Sent: Thursday, April 11, 2002 7:24 AM
Subject: Re: [PSUBS-MAILIST] Isn't 'Mini book review.' anymore--pressure
test


> The real issue, I think, is the fact that liquids are (largely) 
> incompressible. That means that you can take a gallon of water, put it

> in
a
> gallon-sized container and with the proper pump create a head on it 
> which
is or
> arbitrary size providing you can exert sufficient force. The Alvin and
other
> submersibles with hard water-filled trim tanks use this idea in 
> reverse to evacuate their trim tank - the pump can move the water from

> inside the
tank to
> the outside (ambient) side of the tank against the hydrostatic head, 
> hence creating a partial vacuum inside the tank. We're trying to run 
> this
process
> backwards.
> Most of the commercial tanks that are used for pressure testing are 
> fluid-based. This is for the same reasons they hydro test scuba tanks
partially
> filled with water - an explosive failure is far less dangerous if part

> of
the
> volume is filled with water instead of compressed air, which has an
amusingly
> high kinetic energy content.
> I'm less concerned with generating the pressure on a vessel filled 
> with water, actually, and more concerned with sealing a big tank with 
> a door in
it.
> Maybe there's some advice to be gleaned on the subject?
>
> Thanks for the interesing dialogue!
>
> John
>
> John Brownlee
> Chief Systems Administrator
> Scary Monsters Network
> jonnie at scarymonsters dot net
>
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