Originally posted by Lost Yooper
I suspect it's another prime example of a law suit skittish industry over protecting itself, for which I can't blame them. As I recall, the Europeans don't even use burst disks. Perhaps some they can shed some light on their practices.
Mike
The situation in europe:-
1) Tank material - Aluminium tanks aren't unheard of here, however, they represent only a tiny percentage (about 1 to 2% I would guess) of the total. Steel rules. Aluminium was popular for a time in the 70's but no longer.
2) Valves - The UK and the Scandinavian countries use single valves, France, Switzerland, Germany Insist on double valves (ie Y or H valves) - the rest I'm not sure about.
3) Burst disks - Never been used, never likely to be used. This is partly explained by their relavent modes of failure. With such a low percentage of AL cylinders (industrial cyliners are not allowed in Al in the UK for some reason) the risk is even lower - Look at an exploded steel tank and an exploded aluminium. They have very different failure modes. Al literally explodes, whereas steel 'unzips'. No-one that I know of has ever been killed by a failing steel tank. A few years ago, a steel tank let go in my LDS, apparently it made a high pitched squeeking noise as the failure started, which turned into a tearing/gas rushing sound as the failure grew. In total it left a gap in the cyliner of less than an inch long, and about 1/4 wide, and several people with ringing ears, no injuries and no bits of metal flying everywhere.
4) Regulations - all the european countries have their own specifications for tank manufacture and testing. A tank made to french rules with a NF (norm français) stamp won't be filled in the UK, neither will a BS5045 be filled in france, and both won't be filled in germany where it has to be marked TUEV. This is being overcome by the new EN144 (european norm), However, as I have expensively discovered if it is marked EN144 NF (ie complying to the two) it won't be filled in the UK, whereas it is was just marked EN144 it would have no problems! - it is getting confusing at this point!
5) tank measurement and classification. - At least this is all agreed on. Tanks are sold by their internal water volume (ie a 12 L tank, if you took the valve out would hold 12L of beer/wine/water. This is then combined with the WP. So, a 12L tank will come in LP and HP. They are the same physical size, so the HP will just have more air 'squeezed in'
6) Overfilling - (the + sign for the US) - this doesn't exist here at all. Totally Banned / Interdit / Verboten. It is normal that if you have the time to leave your tank for a while it will be filled, allowed to cool and then 'topped off' so when you collect, it is also reasonably common (although illegal) to overfill by 20 bar and let the tank stand to cool down to its WP.
7) Working pressure - European tanks seem to be at slightly higher working pressures, a LP tank is usually 232 Bar (3300PSI), and a HP tank is usually 300Bar (4300Bar), although I might be wrong on this last point.
8) at european prices the statement 'Aluminum forgiving on wallet,Hp steel forgiving on back' by 100days is not true. Al tend to be the same price, if not slightly more expensive.
9) Weight - Since practically all european diving is done Dry, or with 5mm of neoprene minimum Steels hold the advantage. It is quite normal to see drysuited divers with Twin steels as backgass, and two stages made of steel, with still a weightbelt of 5 - 10 Lbs
HTH on giving the European picture.
Jon T
PS, as a european, looking at what happens in the states, The regs are all perfectly logical, but not always necessary (IE a bit OTT, or 'Over The Top') and often appear to be designed to protect people from lawsuits rather than provide a suitable level of public protection.
