Posted by Marc Hall on November 06, 2001 at 18:49:53:
In Reply to: is overfilling why DIR sanctions low pressure steel tanks? posted by Karl S. on November 05, 2001 at 14:30:22:
The overfilling of PST and Faber LP tanks is common practice in certain areas of the country.
In Nothern Florida cave country is quite common
to expect LP tanks to be filled to over 3400 psi
but this practice is not limited to DIR divers or
shops. It's pretty normal to carry you tanks to
a fill station and be asked what mix and what fill pressure you desire in your tanks. (Nitrox 32
and 3600 por favor)
The requirements/need for burst disks and LP
fills is mandated by Department of Transportation
(DOT) who are likely more concerned about the
behavior of the tank during an auto accident then
in how many high pressure cycles the tank can
safely withstand or was designed for.
My understanding is that Europeans have no
requirement for burst disc. The US burst disc
requirement is pretty redundant as the neck
oring at the valve/tank interface will let
loose before the tank explodes if tank is a
viable tank. Obviously if you do something
like bake an aluminum tank it may explode
before either a burst disc or neck oring
relieves the pressure.
Marc Hall
svcfish@yahoo.com