Mailing List Archive Mailing List Archive
CAUTION!
The following post was written by a dive store owner, gas
blender instructor, Trimix diver, and opionated SOB.
Certain parts of this post may be found to be objectionable. Minors,
women and other people who may object to your use of profanity,
should be asked to leave the room.
For the last couple of months I have been reading an excessive
amount of whining posts concerning o2 cleaning, gas fills, and
labelling. I have held my key board as long as I can, and now I going
to tell you the way it ought to be! I have broken this up into a
couple different sections; read what ever you want.
1. Labelling
2. Switching gases, Air, Nitrox below EAN 40, and Trimix
3. Gas Blending, mixes with an FO2 below 40%
4. EAN 41 and above, and Argon
5. Air top offs, and dive shops
6. Duct tape residue
1. Labelling: The purpose of labelling a tank is to identify the
contents of the tank. In the USA, the compressed
gas industry labels all tanks whether it's Propane
for your gas grill, Oxygen for your cutting torch,
or Helium for your balloons. Ownership of the tank
makes no difference. Your Propane tank for your
gas grill and the Propane tanks at the gas
supplier have the same neck contents label. The
reason the tank is labelled is not for gas
supplier, he knows it's a Propane tank by the
style of tank and the valve, but for anyone else
who MIGHT come in contact with the tank. All scuba
should be required to have a neck label; white
background for Air, green for Nitrox, orange for
Trimix, brown for Argon, etc.. Teach all divers at
the entry level what the different labels mean, so
they can be responsible for not using the wrong
tank by accident. Make the labels generic (cheap)
and easily removable for when the contents changes
or the label becomes illegible. Allow space on
Nitrox and Trimix labels for variables such as FO2,
FHE2, etc.. This would not be tough or expensive,
and would keep almost everyone happy. Remember,
the label is not only there for you, but for any
one else who Might come in contact with the tank.
2. Gas switching: Many gas suppliers change the contents in their
tanks simply by changing the neck label and
sometimes repainting the tank. Here is how and why
it is done. Some gases are lumped into a common
family and do not conflict with others in that
family. An example would be Helium and Argon. Both
gases are inert, they don't react to each other,
they both are used as shield gas in welding, they
leave no residue in the tank, and they use the same
type of tank and the same CGA 580 valve. Also in
this family is Argon CO2 ( a combination of Argon
and Carbon Dioxide ) and Stargon ( a combination of
Argon, Carbon Dioxide, and Oxygen ). All these gases
Come in the same type of tank with the same CGA 580
valve. Sometimes gas suppliers run low on one type
of tank and have to convert tanks from a different
type of gas mixture to the one they are short of.
The Compressed Gas Association even has guide lines
for doing this. In some cases it's as simple as
changing the neck label! We should be able to do
this for bottom mixes and travel gases with an FO2
below 40%. You ask," Do you expect us to oxygen
clean all scuba tanks!". The answer is no. Read the
section on Gas Blending.
3. Gas Blending: Dive stores and other facilities who sell Nitrox and
Trimix with an FO2 below 40%, should be required by
law to fill your tank without exposing your tank and
valve to an FO2 of 40% or greater! It's easy, safe,
fast, and how my store fills Nitrox below EAN 40 and
Trimix. Here is how I do it. The store has a cascading
bank of EAN 39. How the EAN 39 is produced is not
important. Once you have EAN 39 you can put it any
scuba tank without Oxygen cleaning that scuba tank
( almost everyone will agree with that ).
To make nitrox with an FO2 of 39% or below, simply
base the tank with Premix ( EAN 39 ) and top with air.
This is simple, and requires no Oxygen cleaning of
customer tanks. Trimix is almost as easy. Base the
tank with Helium, add Premix ( EAN 39 ) to raise the
FO2, and top with Air. This is also simple, and
never exposes the customers tank to an FO2 greater
than 39%. All that's required to do this as opposed
to partial pressure filling in the customer's tank
is 10 or more high pressure Oxygen clean storage
bottles. If it's your business, make the investment, do
it right, and reduce your risk. If all stores would
do it this way, blending gas would be a lot simpler
and all we would have to do is change the contents
label on the neck of the tank.
4. EAN 41 and above, and Argon: Tanks that are for EAN 41 and above
are few and far between. The average technical diver
probably owns two. There appears to have been some
objective testing done by departments of the US
government and members of The Compressed Gas
Association that indicate a need for Oxygen cleaning
above 40%. To date, there have been no objective
scientific tests done to indicate that there is no
need for Oxygen cleaning, or that the level at which
Oxygen cleaning is not required should be raised
above 40%. Until such time as these tests are done,
get your deco tanks cleaned and STOP WHINING!
Argon bottles, since they don't contain a breathable
gas and there have been documented cases of near
fatalities when people have tried to breath off these
bottles mistakenly, should be more boldly labelled and
probably painted brown to avoid confusion. This
shouldn't be any big deal, since most Argon tanks are
very small and generally only used for drysuit inflation.
5. Air top offs, and dive shops: When a customer brings in a tank for
an Air fill, we blow some gas off and watch his expression
to see if it changes. When a diver bring in a tank that he
has based with either Oxygen or Helium, he has imposed
an unreasonable liability on me. My store is liable for the
mixture in that tank regardless of the fact that I didn't put
the Oxygen or Helium in the tank. Lets face it, most of
you clowns who play this game have no formal gas
blending training, accurate gauges, or even own an Oxygen
analyzer. You all are your own worst enemy! My advice
to the stores in North Carolina who have to deal with
these type of clowns, is two blow a couple hundred
pounds out of each tank before you fill it. If the
customer screams, empty their tanks all the way, and
then throw the clown out of your store. For those of
you who go to N.C. and can't get the mix you want
from the dive shop, do what I have done since
1982. I bring all my gas with me. I started diving
Hatteras N.C. in 1982 before there was a dive shop
there. The choice was either the portable compressor
or enough tanks for four days of diving. Even now,
when we go dive the "Clark" or the "Monitor" we still
have to bring all our gas because nobody pumps Trimix
down there. Finally, if you keep bringing all your
gas with you and making a point of telling the owner
of the store why he is not getting your business, maybe
he will change when he sees there is enough demand.
For those of you who don't have enough tanks to do
this, borrow some from your friends. Whatever you
decide to do, please......STOP FUCKING WHINING!
6. Duct tape residue: I have found that an Oxygen Acetylene torch
works real well when turned up high, for removing duct
tape residue...............just kidding.
Ted
Ted Green (owner)
Tidewater Aquatics (Dive Store)
Salisbury Maryland USA
TDI IT #029
SSI MI #178
The world contains but three types of people:
1. Those who make things happen.
2. Those who watch things happen.
3. Those who wonder what happened.
--
Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
Send list subscription 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]