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aluminium Vs. Steel doubles

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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will_tekkie

New Member
Nov 24, 2002
23
0
0
Hi dear friends....I´ve spent several years diving in south america (venezuela...i know no too many people have been there but it´s pretty nice)...i love aluminium 80's for doubles with wetsuit....but here in europe the most divers fell in love for steels ones...I would like to know your opinion about this subject. Aluminiun means: cheaper, less maintenance and safer with wetsuit in open water diving....I specially hate steel cylinders for stages!!!!!
 

firefox

depthcrazy wreckhunter
Nov 11, 2002
19
6
0
46
europe and the steel tanks ...

dear will,

in europe alu-tanks are not that established as on other continents. there are several reasons for this fact - one is that (espacially in central europe, where i live) you are not allowed to sell or fill alu tanks. it is forbidden by law to use them.

in austria each diver is obliged to have his tanks checked in certain intervalls to get a check certificate, but no one would get a certificate for alu tanks here. germany, swiss, italy and many other european countries have similar restrictions.

another fact is that alu is softer then steel. so seen from this point of view alu is not necessarily safer than steel.

sure, there are possibilities to get alu-tanks - but as far as i know alu-tanks find there use in navigation diving competition as they are antimagnetic

for reducing weight it is more common to use composite tanks...
 

will_tekkie

New Member
Nov 24, 2002
23
0
0
Thanks Firefox for your information.

I agree with you about the reasons..but laws sometimes are obsolete...laws aren´t religition can and should be changed if new products and developments shows advantanges. Alu are safe. Europeans love manual cars...americans prefer automatic cars..Are automatic cars unsafe for that???.. ..Alu tanks (millions) are used around the world..they are cheaper than steel..they tend to shows less corrosion problems, usually related with bad users ( just look below boots). It´s true alu is less strong ( less tensile stregth and hardness) than steel but it just implies more thinkness and a different surface treatment. It´s a different design. They are different operationals procedures on inspections and transport. Low pressure steel tanks are ok...better than alu ( almost the same weight...better bouyancy caracteristic, etc) but the rest are definitely worse in double tanks applications with WETSUITS in OPEN WATER with deeps up to 200- 250 ft. Imagine a diver with a double open circuit ring with a couple of 90´s steels with stages made of steel as well. What will be happen if your BC have a failure? just add a steel backplate tooand you haven´t a drysuit, the diver refered will be a bathysphere aim to the bottom . When deco and travel stages are considered steel are definitely WORSE than alu. Why... the last ones are closer to neutral bouyancy than steel, lighter and allow a better stability.

Composite tanks are VERY nice..B-2´s bombers are made with composites materials are very NICE too. AND both are very Expensive. I´m a average diver with limited budget.

Of course all these reasons are based in my own experience and preferences...but this law which do not allows to choose between alu and steel is one of that silly things which have made that the most developments on gear and techniques in tech diving come from US not europe.
 

sponge bob

New Member
Dec 13, 2002
4
1
0
In North America it is considered safer to dive with aluminum doubles when you are in a wet suit because of the inherent buoyancy of the al tanks as they empty and the lack of redundant buoyancy with a wetsuit.
When diving dry, most divers prefer steel doubles since they are more negative and thus the diver requires less (or no) additional ballast.
In either case, al stages are preferred since the extra weight (under water) of steel cylinders would be just too much of a good thing.
As for the safety of the cylinders due to corrosion (with steel) or cracking (with aluminum), there is some controversey but no official difference. Both types are required to have an internal inspection annually and hydrotested every 5 years.
Since diving in our Canadian / US great lakes is usually cold, I'm diving dry and both sets doubles are steel.
I prefer steel singles as well because less weight is needed. They cost more and require a bit more care, but I'm not a very big guy so leaving 5 lbs of lead behind for each tank is sure worth it for me.
 
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