whiskeyriver
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whats most common? which gives more bottom time? which one has the longest life? please help me with this
Aluminum 80 or steel 100
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I would say Al80's are more popular as they are cheap. However they might not be the best for you depending on where you dive. The 100's will give you more time as the hold more air than an AL80. An added benefit of the 100's are that they allow you to take some lead off your waist.
I have both and tend to use the steels more as they hold more air and allow me to use less weight.
I have both and tend to use the steels more as they hold more air and allow me to use less weight.
Al80 is most common. The steel 100 has 20.something more cubic feet of gas so it will last you longer, and steel has a longer expected life than aluminum if you take care of it (make sure to remove/clean the tank boot after salt water dives, and don't get wet fills).
OP
whiskeyriver
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when you say wet fills... are referring to fills abourd a boat?
Bob DBF
Contributor
When I initially bought tanks I got 2 AL 80's because it was inconvenient to plan my dive outings around dive shop hours and I wanted at least two dives for the day. At the time the steel tanks were smaller and more expensive, I could buy 2 AL for considerably less than 2 steel. Since then I have added steel tanks, which I like better and dive more often.
I have both AL and Steel that have lasted over 20 years. Buying used is great only if you do plenty of homework.
Bob
I have both AL and Steel that have lasted over 20 years. Buying used is great only if you do plenty of homework.
Bob
OP
whiskeyriver
Registered
thanks for the info guys. it does help
With wet fills I mean fills that have a high moisture content. I don't know how you would know if you were getting a wet fill, other than to open up your tank and check every couple of fills (assuming you get it filled at the same place all of the time). Having moisture or water in the tank can make a steel tank rust.
I actually had this conversation with Bob Sherwood of GUE regarding a doubles setup. He said he prefers the aluminum tanks to steel since they are cheaper initially ($150 vs $350) and the long term cost is less as well.
The steel tanks need a hydro inspection every five years. If it is not done properly the inside of the tanks will rust. That actually happened to several tanks at my local shop. The inside of the tanks need to be coated after the hydro is complete (can't remember the name).
The steel tanks need a hydro inspection every five years. If it is not done properly the inside of the tanks will rust. That actually happened to several tanks at my local shop. The inside of the tanks need to be coated after the hydro is complete (can't remember the name).
The well intended but misleading information is starting to accumulate. Lets clarify a few things.
AL 80s hold 77 cu ft and tend to be relatively inexpensive - $180-$200. They don't rust, but they do corrode so if you have salt water trapped in the valve that gets blown into the tank during the fill, you still have a problem. Same with a really wet air fill. The only plus is that the oxidation process with aluminum is somewhat self sealing, but if you have actual water in the tank, that won't make any difference.
Worthington X7-100s hold 100 cu ft at 3442 psi. They do have the potential to rust internally, but if you are using good quality (properly dry) gas, the tank will go years before any flash rust forms to the point it needs to be removed. Tumbling is common every 5 to 10 years but is not a big deal nor is it very expensive. The idea is to remove any flash rust before it builds up to the point it obscures the surface of the tank and/or collects moisture and promotes pitting.
Steel tanks do cost more $300-350.
An AL 80 weighs 31 pounds while an X7-100 weighs 33, but the AL 80 is 4 pounds positive when empty while the X7-100 is 2.5 pounds negative. So you can remove 6.5 pounds of weight compared to what you use with an AL80 - an overall savings in weight carried of 4.5 pounds.
Both steel and aluminum tanks will need a hydro test every 5 years.
One often heard concern with the 3442 psi steel tanks is the concern that you may not be able to get a full fill on a boat etc. However an x7-100 will hold the following:
3442 psi = 100 cu ft
3300 psi = 95.9 cu ft
3000 psi = 87.1 cu ft
2800 psi = 81.34 cu ft
2650 psi = 77 cu ft
So in effect, to do worse than a fully filled AL 80 you'd need to be underfilled to less than 2650 psi. More to the point, if a boat's comressor can only manage 3000 psi, the AL80 will cool to about 2800 psi (71.9 cu ft) while the x7-100 will hold 10 more cu ft at the same pressure.
AL 80s hold 77 cu ft and tend to be relatively inexpensive - $180-$200. They don't rust, but they do corrode so if you have salt water trapped in the valve that gets blown into the tank during the fill, you still have a problem. Same with a really wet air fill. The only plus is that the oxidation process with aluminum is somewhat self sealing, but if you have actual water in the tank, that won't make any difference.
Worthington X7-100s hold 100 cu ft at 3442 psi. They do have the potential to rust internally, but if you are using good quality (properly dry) gas, the tank will go years before any flash rust forms to the point it needs to be removed. Tumbling is common every 5 to 10 years but is not a big deal nor is it very expensive. The idea is to remove any flash rust before it builds up to the point it obscures the surface of the tank and/or collects moisture and promotes pitting.
Steel tanks do cost more $300-350.
An AL 80 weighs 31 pounds while an X7-100 weighs 33, but the AL 80 is 4 pounds positive when empty while the X7-100 is 2.5 pounds negative. So you can remove 6.5 pounds of weight compared to what you use with an AL80 - an overall savings in weight carried of 4.5 pounds.
Both steel and aluminum tanks will need a hydro test every 5 years.
One often heard concern with the 3442 psi steel tanks is the concern that you may not be able to get a full fill on a boat etc. However an x7-100 will hold the following:
3442 psi = 100 cu ft
3300 psi = 95.9 cu ft
3000 psi = 87.1 cu ft
2800 psi = 81.34 cu ft
2650 psi = 77 cu ft
So in effect, to do worse than a fully filled AL 80 you'd need to be underfilled to less than 2650 psi. More to the point, if a boat's comressor can only manage 3000 psi, the AL80 will cool to about 2800 psi (71.9 cu ft) while the x7-100 will hold 10 more cu ft at the same pressure.
Wayward Son
Contributor
all tanks have to get a hydro every 5 years, not just steel.
I'm a real fan of the HP (3442 PSI) 100CF steels. My personal tanks are 3442 117's, but my wife's are 100's. She can't handle the extra weight of the 117's.
I still have 3 AL80's. The only reason being that I have not found good enough deals on 3442 100's to replace them with.
I'm a real fan of the HP (3442 PSI) 100CF steels. My personal tanks are 3442 117's, but my wife's are 100's. She can't handle the extra weight of the 117's.
I still have 3 AL80's. The only reason being that I have not found good enough deals on 3442 100's to replace them with.
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