On 8 Feb 2006 17:47:48 GMT, Rory O'Conor
wrote:

Having tested the cylinders, they may want to 'O2 clean'
the cylinder before filling it with pure Oxygen. Because
there seems to be a worry that any stray hydrocarbons
will set off an explosion.

VERY WISE.

The diving shop said that they would replace all the
O rings on cleaning. DG dont have any o ring sets.
So I am currently wondering what to do if I reach that
stage.

I'd guess there to be either 1 or 2. It will likely be a standard
size, either AN or metric. Does DG give the sizes? I'd guess that
flourocarbon (tradename is commonly used, Viton, but duPont doesn't
like that) is better than nitrile or buna (perbunan in Germany, I
think). Your local seal house can get you some; the minimum order may
hurt, but the individual units won't be bad.

I am not sure how easy it is to get Oxygen at 200 bar
from diving shops, because most is mixed with air as
nitox or trimix. Thus they can start with a relatively
low oxygen pressure (50-100 bar) and then top it up
to 200 bar with breathing air.

In the US, "standard" cylinders are about 150 bar fresh from the
supplier; I don't know what other pressures are used. I work with
Nitrogen cylinders at 415 bar.