Gone for diving
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So if my math is correct. 4800 psi is hydro pressure???? For aluminum 80...
Question regarding tank fills
- Thread starter CaptainPanda
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Charles2
Contributor
I very well could be wrong. I often am. I am just asking for a good reference that states that it is OK to overfill steel 3AA and not to overfill 3AL. The only links provided so far have been anecdotal evidence.
As I said, "I am not in favor of significantly overfilling any tank; but, why aren't 3AL tanks as tolerant of overfilling as 3AA tanks?"
You won't find it. No manufacturer is going to say that. You need to do the research and reach a conclusion that works for you. Every manufacturer will tell you NOT to overfill their cylinders. Period.
Neither am I. I only overfill my AL tanks by maybe 5% and my steels by 10%.
Again, aluminum and steel have different characteristics. I'm not a metallurgical engineer. I've simply reached a conclusion based upon reading over the years. I can't point you to one source that will answer all of your questions.
CT-Rich
Contributor
The over filling of steel tanks probably originated with the steel LP tanks getting a plus designation. Tanks with the plus could get an extra 10% fill. Once it was no longer had the plus it would be filled to its standard fill pressure. AL tank never had those designation. Combined with the material being more brittle and having a service life that is much shorter than a steel tank and more susceptible to damage and cracking, it is not as attractive to over fill AL cylinders.
Hydro testing is a test in a controlled environment where they are looking to see if the tank still meets structural specifications for the safe transport of the full cylinders. The tank in mostly filled with incompressible water and they are not dragging it around a dive site or leaving it in the back of a hot car. A catastrophic failure during a hydro is unlikely to kill the tester.
Hydro testing is a test in a controlled environment where they are looking to see if the tank still meets structural specifications for the safe transport of the full cylinders. The tank in mostly filled with incompressible water and they are not dragging it around a dive site or leaving it in the back of a hot car. A catastrophic failure during a hydro is unlikely to kill the tester.
Is the aluminum that much thicker on a Al100? That is filled to 3300psi to get to 100cu ft. Theoretically anyway. I won't request those in the Caribbean because they are seldom if ever filled to proper working pressure and their buoyancy sucks.
60plus
Contributor
Hydraulic (water filled) testing is often done at about 1.5 times normal working pressure, so a 230 bar / 3300 psi tank would probably be tested at around 4800 psi.. I UK and at foreign dive centres I use cylinder are always well above 3000 psi. I would complain if they were less than 220 bar / 3200 PSI, as they are selling you short and reducing your dive time.
Gone for diving
Contributor
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