[Date Prev][Date Next]
[Chronological]
[Thread]
[Top]
Re: [PSUBS-MAILIST] Gathering Material to build mini sub
Here is the results of a quick search for vapor pressure of propane (working pressure of the tank) at
various temps.
http://www.gasplants.com/property.htm
In other word that tank in your yard is at 109 psi during normal summer weather (70 degrees) and 172 psi
at 100 degrees. Of course the temp. of the propane usually doesn't hit the peak air temps unless they
persist for days and use of propane lowers the temp somewhat. The tanks are designed to take worst
case temps. Bear in mind that this is internal pressure, the ratings for extenal pressure (pressure hull) are
considerably less and you have no reliable way to figure what that is. Used tanks will almost certainly be
weaker than new.
I'm not taking any position on propane tanks as pressure hulls, pro or con. I've considered them in the
past and they may even have a place for limited depth Psubs, but I also tend to agree with the point that
you can build something you know for about the same price.
Greg
Date sent: Sun, 21 Apr 2002 15:29:58 -0500
To: personal_submersibles@psubs.org
From: David Buchner <buchner@wcta.net>
Subject: Re: [PSUBS-MAILIST] Gathering Material to build mini sub
Send reply to: personal_submersibles@psubs.org
> At 10:17 -0500 4/21/02, Mark Steed wrote:
> >I don't know if it has been mentioned here before, but I will
> >include an experience I had with propane tanks. While converting
> >one for use in an entirely different manner than submersibles,it
> >was discovered that the propane literally seeps into the pores of
> >the metal itself and is almost impossible to remove. The amount of
> >seepage varies with the condition of the interior metal surface.
> >The only way to effectively remove the stuff is to make a large
> >enough opening in the tank (without sparks!) and once in a safe
> >location, burn the stuff out. I was totally amazed by the force of
> >the burning residue left in an "empty" propane tank. Any
> >conversion,or for that matter,any work on propane tanks should
> >proceed with extreme caution. I do not recommend it. Mark Steed
>
> My dad converted a smaller (100 lb; the tall narrow ones) propane tank into a low-pressure air tank for a
> cannon to fire potatoes and stuff. I think what he did was remove the valve and fill up the tank with water
> all the way to the top before cutting the hole bigger and welding his 2" pipe to it.
>
> Also, he's got a lifetime of experience with welding and inspecting high-pressure stuff - steam pipes and
> boilers and whatnot - and he doesn't fill his formerly-propane tank with any more than 40 psi air. I don't
> know what pressure a full propane tank usually holds, but I'm sure it's more than that. He's sometimes kinda
> reckless, so I take this as some measure of how serious this is. Something about how this tank was figured by
> engineers to do a certain thing and ANY use of it other than that is a whole 'nother unknown thing. Also, an
> old tank has been cycled lots of times: full, empty, full, empty - and cold, warm, cold warm - and there's no
> guarantee how much of even that original strength it still has. --
>
> David
> buchner@wcta.net - MN, USA
> http://customer.wcta.net/buchner