Why are 300 bar tanks not available in North America?

[KevinNM]

The only DoT approved 300 bar scuba tanks are the hoop wrapped luxfers, right? I've wondered why that is myself, but I think that is the case?

 

[NAM001]

Storker,

What safety factor does Norway require 2:1 3:1 cause it cant be 4:1 like in the US The weight of a tank that will support 18000 psi for a min burst pressure is too much for the normal guy to carry.

I have several 10L 300 bar tanks in my attic. I prefer those over my 15L 200 bar, because they weigh about the same, has the same nominal capacity (not accounting for the 5-10% capacity loss due to compressibility effects) and are more negative due to the smaller volume. That means I need to carry less weight, and my rig is actually lighter.

 

[Storker]

Storker,

What safety factor does Norway require 2:1 3:1 cause it cant be 4:1 like in the US The weight of a tank that will support 18000 psi for a min burst pressure is too much for the normal guy to carry.

Never heard anyone talking about safety factors.

AFAIK, hydro test pressure for a 300 bar tank is 450 bar, i.e. 50% above working pressure. The hydro pressure is stamped on the tank neck, as is working pressure, tank weight, serial # and some other numbers.

I don't think this is particular for Norway, I belive the test pressure and stamps are the same across the European countries. How often a hydro test is required varies, though. In Norway, that's three years after production date, and then every second year for SCUBA tanks and AFAIK every fifth year for tanks used topside.


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[Yoyodyne-88]

No they are not. That is a myth they have the same form factor but are made of different alloys.

I may have been misinformed. I'd be interested in seeing the source material supporting your statement.

 

[NAM001]

I suspect that none talkes about it untill they try to bring those tanks to the us and want to get them filled. Check out ebay for tanks that are for sale and do not have the DOT stamp on them. With out the DOT they are now paper weights.

Never heard anyone talking about safety factors.

AFAIK, hydro test pressure for a 300 bar tank is 450 bar, i.e. 50% above working pressure. The hydro pressure is stamped on the tank neck, as is working pressure, tank weight, serial # and some other numbers.

I don't think this is particular for Norway, I belive the test pressure and stamps are the same across the European countries. How often a hydro test is required varies, though. In Norway, that's three years after production date, and then every second year for SCUBA tanks and AFAIK every fifth year for tanks used topside.


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[Storker]

I suspect that none talkes about it untill they try to bring those tanks to the us and want to get them filled. Check out ebay for tanks that are for sale and do not have the DOT stamp on them. With out the DOT they are now paper weights.

You're in the US. You asked about how it is on this side of the pond. I answered. We don't require a DOT stamp, since the DOT is a US agency and we live in Europe.

And who the heck is going to go through the hassle of lugging SCUBA tanks on an overseas flight? That's even a bigger PITA than lugging weights. A steel single weighs at least 10-15 kg and will take more than half of your luggage allowance on a coach class ticket. Do you use doubles? You need a business class ticket to bring anything else than your tanks. In addition, you need to empty the tank completely and unscrew the tank valve. Which may well require a viz. No-one with half a brain brings their own tanks on a plane if it's at all possible to avoid it.

However, you need to have a current hydro stamp also on this side of the pond.

 

[Agility]

And then there are carbon 300 tanks, much lighter than steel or alum tanks and rated to 300 bar CARBONDIVE 300 - Carbon Scuba Tanks, Diving Equipment, Worthington

 

[Storker]

Light tanks sound nice. Until you realize that they're going to make you positively buoyant unless you compensate by adding more weight to your belt or rig.

Up here in cold water country, steel beats Al since you have to carry extra weight anyway. Tank weight has absolutely no effect on total rig weight.


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[NAM001]

This is not a battle here. There was a statement made that the 300 bar tanks have no signifigant weight difference than US 200 bar tanks. That is untrue under the DOT requirements that are based on a 4:1 safety margin. It can only be true if the safety factor is much less which is common in europe. Its not saying that it is bad , only different. Because europes standards are substandard to DOT requirements europes tanks can not be filled in the US because thier stamped working pressure is not in accordance with the DOT requirements that are based on the tanks safety factor. The lower standards also explain why a european 300 bar tank can weigh the same or near same as a US 200 bar tank. I understand you are on the other side of the pond. This issue is about the difference in the governing bodies regulations, which do not prermit eupopean tanks to be serviced in the US. We will accept TC tanks for the very reason we reject european tanks. Its the standards.

You're in the US. You asked about how it is on this side of the pond. I answered. We don't require a DOT stamp, since the DOT is a US agency and we live in Europe.

And who the heck is going to go through the hassle of lugging SCUBA tanks on an overseas flight? That's even a bigger PITA than lugging weights. A steel single weighs at least 10-15 kg and will take more than half of your luggage allowance on a coach class ticket. Do you use doubles? You need a business class ticket to bring anything else than your tanks. In addition, you need to empty the tank completely and unscrew the tank valve. Which may well require a viz. No-one with half a brain brings their own tanks on a plane if it's at all possible to avoid it.

However, you need to have a current hydro stamp also on this side of the pond.

 

[BRT]

I just ran some quick calcs on the Carbon 300 tanks. I may have made an error but it looks like you could carry 130 cu ft with a total weight about 20# less than diving a Worthington steel 3442 130. Maybe that is why Worthington got out of the steel scuba cylinder business. Somebody else should run the numbers.