[PSUBS-MAILIST] just more calc

[via Personal_Submersibles]

Hello, Roberto,
 
The LPG tanks are designed to contain internal pressure, not to withstand  
external pressure.  Also the hydrocarbons from the gas migrate into the  
metal and interfere with the integrity of new welds.  A few people have  made 
very shallow subs from LPG used tanks, but you wouldn't really gain much  
cost advantage, and you would sacrifice capability and safety.  You would  also 
run into other problems installing the hull penetrations. Many of us  
initially thought of using an old propane tank, but quickly discarded the  idea.
 
On the Psubs site if you will go to PSUBS Community, then  Projects & 
Photos, you will be able to look at the journals of the  building process of a 
number of subs.  These two links are  excellent:  
http://www.psubs.org/projects/1245611411/kw350trustworthy/
http://www.guernseysubmarine.com/   You will learn a lot from both of them.
 
The process of building a sub from an existing design takes a long  time.  
Creating a new design takes much longer.  
 
Best wishes,
Jim T. 
 
 
In a message dated 11/12/2014 2:52:30 P.M. Central Standard Time,  
personal_submersibles at psubs.org writes:

 
Hi Roberto,
>>>learn  that i can be safe on a composite hull, even a wood hull below 
the 100 ft i  can dive even on an oil drum ....
   NO you won't be safe with any of those 3. Years ago we calculated that 
an oil  drum wouldn't be safe to 15ft, & it also depends on it's  condition.
Fiberglass  is very difficult to analyze for strength due to the human 
equation, the  saturation of the cloth & the fact that the cloth has different 
strengths  in
different  directions. At 100ft there is about 7,200lb pressure on every 
square foot of  your hull, so calculations have to be very accurate to avoid 
being paste in a  can on the sea bed:).
Did  you see Phil Nuyten's paper on life support. It is very good.
Alan


 
  
____________________________________
 From: roberto alvarez via  Personal_Submersibles 
<personal_submersibles at psubs.org>
To: personal_submersibles at psubs.org  
Sent: Thursday, November 13,  2014 7:11 AM
Subject:  [PSUBS-MAILIST] just more calc



 
 
 
 
Good morning this weekend i read the  book on the psubs website as i can 
read ,is a collection of designs and  experiences, i am working with the air 
volume and CO2 production, this because  i divide the project in 3 main 
areas, pressure hull-life support-control &  propultion

learn that i can be safe on a composite hull, even a wood  hull below the 
100 ft i can dive even on an oil drum , the  main concern  will be O2 
depletion and CO2 pollution we exhale 1.7 cubic feet hour  and  by coincidence we 
need 1.7 cubic meters per day

will use this info  for a better internal space before any other 
consideration, yesterday i went  to a LPG truck scrap yard, found that the inside of 
the tanks are free of  rust, they have  wave brakers ( internal plates ) have 
inspection holes  with 2 inch tempered glass and  build from 0.500 inch 
plate, 54 inch in  diameter and 12 feet lengh,  


may be other option



 
 








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