AL vs. Steel tanks

Expense is a minor point...
it's the "weight at end of the dive" one remains boyant one isn't.

Your dive instructor should have gone over all this with you.

On Tue, 22 Jun 2004 21:54:04 -0500, "Mavric" <N/A> wrote:

>i have been diving for allmost 1 year now and i want to buy my own tank
>mainly so that we dont have to be back to the dive shop before they close to
>return it.
>
>I was just wondering what would you guys recomend. I do mainly fresh water
>diving. One of are friends that we usually go with has a AL 80 and me and
>my brother just arnt sure what to get. i would kind of like a bigger one
>because me and my brother both are bigger and use a little more air than the
>average person.
>
>Im about 6'2" and weight about 250 lbs. I was just wondering what would
>some of the pros/cons of AL vs. Steel and how big of a tank would be to big?
>
>I know some of the steel are HP and i can switch my regs over to DIN for
>about $50 so that wont be a problem.
>
>
>thanks for any info you can give me.
>
>
>Justin
>
>
>


---
Remove x's to send.

"Josh Assing" <xjoshx@jassing.com> wrote in message
news:uc0id0pjem1si1gnjok129vbbrppettc6c@4ax.com...
>
> Expense is a minor point...
> it's the "weight at end of the dive" one remains boyant one isn't.
>
> Your dive instructor should have gone over all this with you.

Which does not answer his question and depends on the tanks themselves.
Some steel are positive when empty and some Al are negative.
For the most part the difference in most places either adds to or subtracts
from the weight belt.

Perhaps you shoud review what your instructor said.


>
> On Tue, 22 Jun 2004 21:54:04 -0500, "Mavric" <N/A> wrote:
>
> >i have been diving for allmost 1 year now and i want to buy my own tank
> >mainly so that we dont have to be back to the dive shop before they close
to
> >return it.
> >

There are to many variables to answer your question.
However if you spend a lot of time and money at the shop I'd just ask them
to let you keep them over night if it makes sense for you.

If you are looking at higher pressure make sure the shop can and will fill
to the higher pressure.
There are lots of shops that will overfill tanks for you to get in a little
extra time.
http://www.mikepainter.com/dotletter.pdf is a letter that explains that DOT
really does not care what you do with a cylinder.

Mike Painter <mddotpainter@sbcglobal.net> wrote:
>"Josh Assing" <xjoshx@jassing.com> wrote in message
>> Expense is a minor point...
>> it's the "weight at end of the dive" one remains boyant one isn't.
>>
>> Your dive instructor should have gone over all this with you.
>
>Which does not answer his question and depends on the tanks themselves.
>Some steel are positive when empty and some Al are negative.
>For the most part the difference in most places either adds to or subtracts
>from the weight belt.

Nevermind the fact that what the instructor says can hardly be assumed to
be accurate. Sometimes the answer is dictated by the brands stocked by
the dive shop.

>> >i have been diving for allmost 1 year now and i want to buy my own tank
>> >mainly so that we dont have to be back to the dive shop before they close
>> >to return it.

This was a big motivation for me as well. Given the big price differential and
the lack of rust issues, I'd suggest the AL80 for now. I've found the HP steels
prone to needing tumbling, and getting a good fill is hard. If I were to buy
over again I'd aim for lower pressure steels but keep the din valve. Sometimes
you can get great deals buying used tanks.

--
Jason O'Rourke www.jor.com

"Mavric" wrote

> i have been diving for allmost 1 year now and i want to buy my own tank
> mainly so that we dont have to be back to the dive shop before they close
to
> return it.
>
> I was just wondering what would you guys recomend. I do mainly fresh
water
> diving. One of are friends that we usually go with has a AL 80 and me and
> my brother just arnt sure what to get. i would kind of like a bigger one
> because me and my brother both are bigger and use a little more air than
the
> average person.

Buoyance characteristics and capacity are going to be your deciding factors.
Standard 80 aluminum tanks are about 4 lbs buoyant when empty, which is how
most tanks are compared. If you carry less than 4 lbs of lead when using
one of them, then they are the way for you to go. If you carry more than 4
lbs of lead, you might consider one of the higher pressure aluminum tanks.
Catalina and Luxfer both offer them. They're only a little more expensive
than the standard 80s. They fill to 3,300 psi and are available with either
A clamp or DIN valves. A little web research will tell you the sizes
available. These can improve your trim and reduce the lead you carry.
Most divers want enough ditchable weight to allow them to become at least
slightly buoyant, but not much more. HP 100s are even more negative, but
not by much. They have the advantage of holding more gas in about the same
space. PST makes some with valves that will work with both A clamp and DIN
regulators. They're about twice the cost of aluminum tanks. They also
require a bit more care to ensure water does not get into them, particularly
salt water. Steel tanks can rust.

Lee

In news:Lee Bell <leebell@ix.netcom.com> typed:
> "Mavric" wrote
>

> They also require a bit more care to ensure
> water does not get into them, particularly salt water. Steel tanks
> can rust.
>


Sorry, but I had to but in. Aluminum will oxidize just as fast and even
faster than steel under certain circumstances; just leave a penny on
deck of an aluminum boat and see how fast it drills trough.

It's a recurrent misconception that aluminum doesn't rust, just because
the oxide is not red in color.



--
www.odysea.ca

In news:Charlie Hammond <hammond@not@peek.ssr.hp.com> typed:
> In article <VViCc.29611$Nz.1322681@news20.bellglobal.com>,
> "Deco_time" <coral_city2000@NOSPAMyahoo.ca> writes:
>
>> Sorry, but I had to but in. Aluminum will oxidize just as fast and
>> even faster than steel under certain circumstances; just leave a
>> penny on deck of an aluminum boat and see how fast it drills trough.
>
> Put aside the details that belong in ALT.CHEMISTRY_AND_METALURGY.
> They are not pertinent to SCUBA.
>
> Under the actual circumstances encountered in SCUBA diving,
> observation makes it very clear that AL tanks have far less frequent
> corrosion problems than do steel tanks.
>
> It can be argued that steel tanks are often better than Al, at least
> for certain types of SCUBA diving. However, steel can cost US$1-200
> more for each tank, and corrosion IS a consideration. Given these two
> factors, it is not surprising that the overwhelming majority of SCUBA
> tanks you see in actual use are Aluminum.

We'll have to agree to disagree. The main factor driving the use of alu
over steel is price and then weight; corrosion is not a factor. I've
retired, just last year, two steel 72's due to corrosion pitting; yeah,
but thoses were 32 years old heavily used cylinder. I very much doubt
the two new aluminum one will last that long. Heck, I'm not even sure I
will last that long.

--
www.odysea.ca

In article <VViCc.29611$Nz.1322681@news20.bellglobal.com>,
"Deco_time" <coral_city2000@NOSPAMyahoo.ca> writes:

>Sorry, but I had to but in. Aluminum will oxidize just as fast and even
>faster than steel under certain circumstances; just leave a penny on
>deck of an aluminum boat and see how fast it drills trough.

Put aside the details that belong in ALT.CHEMISTRY_AND_METALURGY.
They are not pertinent to SCUBA.

Under the actual circumstances encountered in SCUBA diving, observation
makes it very clear that AL tanks have far less frequent corrosion
problems than do steel tanks.

It can be argued that steel tanks are often better than Al, at least
for certain types of SCUBA diving. However, steel can cost US$1-200
more for each tank, and corrosion IS a consideration. Given these two
factors, it is not surprising that the overwhelming majority of SCUBA
tanks you see in actual use are Aluminum.

--
Charlie Hammond -- Hewlett-Packard Company -- Ft Lauderdale FL USA
(hammond@not@peek.ssr.hp.com -- remove "@not" when replying)
All opinions expressed are my own and not necessarily my employer's.

> i have been diving for allmost 1 year now and i want to buy my own tank
> mainly so that we dont have to be back to the dive shop before they close
to
> return it.
>
> I was just wondering what would you guys recomend. I do mainly fresh
water
> diving. One of are friends that we usually go with has a AL 80 and me and
> my brother just arnt sure what to get. i would kind of like a bigger one
> because me and my brother both are bigger and use a little more air than
the
> average person.
>
> Im about 6'2" and weight about 250 lbs. I was just wondering what would
> some of the pros/cons of AL vs. Steel and how big of a tank would be to
big?
>
> I know some of the steel are HP and i can switch my regs over to DIN for
> about $50 so that wont be a problem.
>
>
> thanks for any info you can give me.
>

I had two basic reasons for choosing a steel tank over an aluminum tank.

1) I live near the Puget Sound in Washington State. Diving requires either
a fairly thick wetsuit or a drysuit. Instead of diving with 16-18 lbs of
lead I required (at the time of the purchase) nearly 40 lbs of lead. The
steel tank is negatively bouyant when empty which allowed me to remove about
4-6 lbs of lead.

2) I have what is called a barrel chest, I have big lungs. In otherwords I
suck air bigtime. It does not matter how shallow or deep, I am the first to
ascend, average dive time on a 60' dive is 35 minutes. Sometimes 40. I got
the steel tank for extra capacity - it's a 100cuft, and can be preasurrized
to 3500 psi.

Those were my two reasons behind purchasing a steal tank.

Walter

"Mavric" <N/A> wrote in message news:c62dnbml3MzybUXdRVn-vg@tznet.com...

> I know some of the steel are HP and i can switch my regs over to DIN for
> about $50 so that wont be a problem.
>
>
> thanks for any info you can give me.

I have a couple LP steel 104s I will sell you.

Kimber

"Deco_time" <coral_city2000@NOSPAMyahoo.ca> wrote in message
news:VViCc.29611$Nz.1322681@news20.bellglobal.com. ..
> In news:Lee Bell <leebell@ix.netcom.com> typed:
> > "Mavric" wrote
> >
>
> > They also require a bit more care to ensure
> > water does not get into them, particularly salt water. Steel tanks
> > can rust.
> >
>
>
> Sorry, but I had to but in. Aluminum will oxidize just as fast and even
> faster than steel under certain circumstances; just leave a penny on
> deck of an aluminum boat and see how fast it drills trough.

Aluminum oxidizes almost instantly but forms a coat that stops further
oxidation.

A penny on an aluminum boat has nothing to do with oxidation but with the
fact that you now have a battery and electrolysis is the factor.

Keep them both dry and they will be happy until somebody picks up the penny.