Re: Alum vs Steel?


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Posted by Eric Frasco on August 17, 2001 at 13:03:23:

In Reply to: Re: Alum vs Steel? posted by Glenn on August 17, 2001 at 12:33:55:

Glenn makes good points.

One additional concern - are you going to be doing a lot of boat dives or will you be doing beach dives and getting fills on land?

One of the problems with getting fills on boats is that being right on top of the ocean, you tend to have higher humidity in your fills, and the fact that your cylinder is usually dripping wet from the dive, sea water is all over the deck, etc. All this contributes to what is affectionately referred to as "wet" fills. This is much more serious of a concern for a steel cylinder than an aluminum cylinder, because steel will pit and rust, whereas aluminum is more resistant to corrosive attack.

I have to get a light tumble nearly every year on the steel cylinder I use for boat diving.

If you go diving in Florida, you will find that most of the boats provide the cylinders for your dive. And they are almost always aluminum. Steel a lot more maintenance in a constant use situation, and aluminum costs a lot less. The only steel cylinders I ever saw in Florida were ones that were owned by divers.

There is one additional advantage that a steel cylinder has over aluminum on boat trips, and that is the fact that most steel cylinders fill to 2400 psi, as oppossed to 3000 psi for aluminum. Most boats can barely fill to 3000 psi, and it seems that it takes twice as long to get to 3000 psi also. So you have a better chance of getting a full fill when you take steel along on a boat trip.

I've owned both steel and aluminum, and prefer steel, although it costs me a little more in the long run. But it means less lead on my weghtbelt, and that makes a big difference for me.

You can usually pick up a used steel 72 for about what a new aluminum 80 costs. Just make sure it has a good valve (really old steels have 1/2" threads where the valve screws into the cylinder and should be avoided unless you know exactly what to look for - newer steels have 3/4" threads), and a very recent hydro and VIP. If you purchase a used cylinder from anyone (even your buddies), don't pay until it passes hydro and VIP.

-Eric-


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