Why are 300 bar tanks not available in North America?

[JohnN]

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. . . .

So there are Kevlar wrapped 300 bar tanks used by fire departments. At least locally, they are filled by the same LDS that does 'regular' scuba tanks (thus subject to DOT regulations). Are they rated 4:1 too (pressure of ~ 17200 psi) ??

 

[NAM001]

I cant comment specifically on the wrapped tanks but they will have a required safety factor assigned to them. in regards to metal only breathing tanks I believe they are all 4:1. As fire departments go they have their own issues like impact that will surely go into the formula that determines the requirements. I want to say that there is some wrapped scuba tanks. Metal tanks with a wrap on it but they are expensive and limited life as well as a pain in the but to properly handle. I don't k now of anyone that have used them.

[h=3]Design factor and safety factor[edit][/h]The difference between the safety factor and design factor (design safety factor) is as follows: The safety factor is how much the designed part actually will be able to withstand (first "use" from above). The design factor is what the item is required to be able to withstand (second "use"). The design factor is defined for an application (generally provided in advance and often set by regulatory code or policy) and is not an actual calculation, the safety factor is a ratio of maximum strength to intended load for the actual item that was designed.

• Design load being the maximum load the part should ever see in service.

By this definition, a structure with a FOS of exactly 1 will support only the design load and no more. Any additional load will cause the structure to fail. A structure with a FOS of 2 will fail at twice the design load.


links that have safety factors referenced:

http://wheatland.com/images/specs/Working_Pressure_Ratings6-12-09.pdf



[h=1]Air Storage[/h] [h=2]Air Storage[/h]




BAUER High Pressure Air Storage Systems meet the code requirements of either ISO/UN or ASME. Storage systems are available with 5000 psi and 6000 psi ISO/UN cylinders or 5250/7000 psi dual rated ASME cylinders. Optional mounting racks are available.

• ASME vessels with working pressures of 5000 PSI, have a safety factor of 4 to 1.

So there are Kevlar wrapped 300 bar tanks used by fire departments. At least locally, they are filled by the same LDS that does 'regular' scuba tanks (thus subject to DOT regulations). Are they rated 4:1 too (pressure of ~ 17200 psi) ??

 

[KevinNM]

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

Looks interesting. But I can't see any evidence that they are approved by the US DoT for US use.

 

[Leadking]

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

Do a search with my name. Years ago I posted regarding Faber and various test requirements. I get tired of these stupid posts from those that have no understanding of metallurgy.
I worked with Worthington in creation of the X-series of hp (3442psi) cylinders. In order to make the deal work, we had to order 3 heats of specialty steel and the commitment made amounted to millions of dollars. If you have a few million to spare and can get the dive stores to support 300 bar fills, go for it.
p.s. I dove 300 bar cylinders made by PST on my AGA Divator in the 1970's.

---------- Post added May 7th, 2015 at 08:05 PM ----------

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

Look up my old posts about PST and John Dimik for source materials
lp and hp cylinders are dimensionally the same as the same tooling was used. The difference was the steel used in the E 9791 cylinder. For "proof" all you need to do is read the DOT exemption certificate.