Tank measures - Imperial vs Metric

[oxyhacker]

Actually, they do. Maybe not a separate version for Norway, but certainly different ones for the US and Europe. What gets confusing, is that they may use the same die set to turn out a euro and a US tank, but with different steel alloys and heat treating. So the tanks will be very similar in size and weight, so people may assume they are the same, but they may be very different in other mechanical properties due to the different metallurgy and heat treating.

Re HP and LP, in the dive world the terms are used informally, and there are no official definitions. Most of us would agree that 2640 psi is LP and 3500 psi HP, but 3442 psi/232 bar is anyone's call.

I have a hard time imagining faber making a tank very different for the US market vs. the Norwegian market and the numbers dont match up that exact either, but that could of course be a matter of bar vs atm again just to make it all a bit more messy..
And would a 15 liter 230 bar bottle, which ideally hold 120 cf be a hp or a lp?

 

[Charlie99]

There is a tradeoff between strength and brittleness. European and US authorities have mandated difference tensile strengths. Per an old post of Leadking
http://www.scubaboard.com/showpost.php?p=1129633&postcount=62

Every tank design by every manufacturer must pass a minimum of 10,000 hydro cycles without fail (6-10 times a minute until fail, new cylinder without corrosion or fatigue issues) as required by DOT
Faber makes no tank greater than 7 inches that can take 4000 psi

U.S.tensile strength (105,000-125,000 psi) is not the same as European tensile strength (135,000-155,000 as required by EN 1964 part 1 and ISO 9809 part 1) and I have test data that shows Faber cylinders delivered to us show a tensile strength of 115,000-123,000 psi (as required by DOT)

US and European tanks are definitely NOT the same, in spite of what many assume when they overfill LP tanks.

 

[GDI]

The way that I use to calculate for a conversion from metric to imperial is that I use a factor of 6.9

1 bar= 1 ata= 14.49 psi: 3000 psi / 14.49 = 207.04 bar

A Al 80 which is actual at 77.4 cu ft @3000 psi/207 bar equates to 11.23 lt tanks = 77.4 /6.9

 

[Plug]

Here in Oz, when I started diving, 11.1 litres at 207 bar were referred to as 80s, 11.6 litres at 232 bars were referred to as 95s and 12.2 were referred to as 100s.

Now we just go by the water capacities, much easier really.

Plug