Mailing List Archive Mailing List Archive
> From: atikkan@ix*.ne*.co* (EE Atikkan )
>
> The pressure in an empty the tank is 1 ATA (unless we assume that the
> tank, after being drained, ws kept open & was subjected to cooling or
> heating or was exposed to P > or < 1 ATA). Thus any gas phase
> contaminants can enter only via diffusion, a relatively slow process.
> The next issue is the conc of said gas phase contaminants in the
> ambient environment. Obviously not very high, as that would render the
> ambient environment hazardous.
>
> Thus it appears that that contaminant entry into a fully depleted (@ 1
> ata) tank of any type, maintained in a healthy environment becomes a
> non issue.
>
It seams that I need to explain how containants (primarily salt
water) get into tanks:
After a day of ocean diving off a boat, the used tanks are strapped
in the tank rack on the back of the boat exposed to salt spray. On
particularly nasty days, everything on the back of the boat gets
throughly soaked by salt water spray. During this soaking, the hole
through which the air comes out of the valve, gets filled with salt
water. If the valve isn't opened and the water blown out before the
tank is filled, the water will be pumped into the tank during the
filling process. While this contamination is more common when tanks
are filled on dive boats, it also occurs in dive stores. The culprit
is a lazy or untrained tank filling person.
As for tanks with their valves left open, I have visualed more than
one tank like this that had almost an ounce of salt water in it, when
it was brought into my store in the above condition. DIN valves act
just like funnels when pointed into salt spray driven by the wind.
While less than 20% of the tanks that I visual because they come into
my store empty valve open, have any contamination. Those that have
salt water in them are nasty, and are usually pitted after they have
been cleaned.
While it is unlikely that commercial oxygen cylinders will see this kind of
contamination, there is no good reason not to leave some gas in the
cylinder and the valve closed. In fact, the neck label on my 251 cuft.
commercial oxygen cylinders says, "return with at least 25 psi".
Steve Lindblom writes:
>Just out of curiosity, Ted, do you do a full visual, and charge for
>it, or a free peek for contaminants visual?
It depends on whether the customer complains about having to have the
tank inspected, or if he is genuinely concerned about the possibility
of water having gotten in his tank. If you are going to act like an ass when
you screw up, you're going to pay!
Ted
Ted Green (Owner)
Tidewater Aquatics (Dive Store)
Salisbury Maryland USA
Master Instructor SSI #178
Trimix Instructor TDI #029
--
Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]