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WHY THE WKPP AND G.U.E. DO BOTTLE MARKING THE WAY THEY DO
The big risk in gas diving is breathing the wrong gas. The WKPP
developed as part of its overall system a simple methodolgy for
preventing this.
Bottles are marked horizontally on either side in the orientation of
the diver as to the maximum operating depth of the bottle in three inch
high numbers. It's that simple.
Since "20" can look like "70" the 20 foot bottle is also marked
"OXYGEN" horizontally under the "20" (not necessary in the metric
system). The diver's name is also on the bottles.
With thousands of man dives of decompression results in the field,
we settled on standard decompresion gasses: oxygen from 20 feet, 50%
oxygen from 70 feet, 35% oxygen from 120 feet, and 18% oxygen from 240
feet for deco, with all gases conforming to a minimum standard of 120
feet AED and 1.6 maximum ppo2 for deco ( with 100 AED and 1.4 maximum
ppo2 for diving ). Bottom tanks are labeled for maximum operating depth
as well.
There is no excuse for not permanently and properly marking bottles
no matter what gas is used. It is your life we are betting. Painted
numbers can be knocked off with a swipe of PVC cleaner, and new ones
painted on instantly. Tape can be used also, but nothing should be on
the tank as to the contents other than the MOD and the dated analysis.
Clean, uncluttered tanks are safer. They say a lot about the person
diving them.
With the tanks correctly marked, we fill them according to the
following regimen. Two pieces of tape are placed on the empty tank.
After adding one gas, but before disconnecting it from the whip, one
tape is marked with the date and the gas psi just added. The whip is
removed and the next gas added. The same proceedure is followed, marking
the addition of the gas. The tank can then be analyzed if heliox or to
see what the helium percent is by getting the oxygen percent, or the
tank is topped with air. At that point the tank is analyzed and the
analysis is written on the other piece of tape along with the date, the
first piece of tape is then used to cover the tank valve mouth
indicating a full tank.
For all tanks the analysis is left on until ready to dive, but can
be removed at that point since the identification is by MOD only.
Doubles whether used or not and unused stages must re-taped and dated as
to analysis for travelling and storage. More smart people have been
killed by failing to observe this rule than any other. To keep it
simple, don't dive anything that does not have a current analysis. When
in doubt, check it out.
With MOD it makes no difference where the bottles are located on the
diver, but there should be no effort to identify a gas by its position -
this leads to error. Both the diver and his buddies whould be able to
clearly see the MOD of the gas being breathed as a check on each other.
The correct proceedure when ready to breathe a gas is to locate the
correct bottle by the MOD, remove the reg, place that reg around the
neck and into the mouth, then go back and re-locate the correct bottle,
and turn it on. IF YOU CAN BREATHE, YOU ARE BREATHING THE RIGHT GAS.
All bottles are turned off and the regs parked on the bottle when
not in use - ALWAYS. This also makes buddy idenfication of your
breathing gas easier in wreck diving where all bottles are carried. In
cave, we NEVER carry a bottle past its MOD. Trying to maximize PPO2 past
a detph for purposes of fear of decompresion is too stupid to
comtemplate given the risk assumed in the process.
If you can not see the bottle, and can not identify the gas, you
DON'T breathe it. You stick with what you know is ok until you can make
a positive id. Missing a litle deco gas is better than dying. Betting on
a system where any error cound have been made ( like putting the wrong
cover on a reg ) is inadequate for life bets.
All of our regs look the same - we do not take the chance of trying
to code regs for gases . This allows putting the wrong reg on the wrong
bottle, or the wrong cover on the wrong reg, among other things. It is
akin to loading one gun with blanks and one with real bullets, and then
trying to identify them in a dark closet before putting one to your head
and pulling the trigger. Sound preposterous? This is exactly what you
are doing if you code regs in any way. Oxygen kills you as dead as any
gun.
On a more practical note, we leave our second stages hand tight on
the hoses so we can change them out if one starts freeflowing. This way
the main regs can be replaced with the stage regs ( which bottles are
turned off anyway until used), and then the stage regs switched around
to provide something that works without killing the dive. This is SOP on
long dives. This identical reg business also prevents any problem of
switching seconds before a dive and then forgetting about it.
With the back gas , ALWAYS our deepest gas, we can always identify
those regs. The backup is hung around the neck in the DIR system, and
the other is attached to the long hose - both easy to identify. In cave
diving, we do not carry a gas through or past it rated depth. You can
see that for ocean diving , keeping the bottles turned off is the next
best thing .
You can see that in teaching gas diving of any kind, the convenience
of the MOD check on each other becomes paramount. Trying to id a
student's gas by little labels, stickers, or a plethora of "nitrox "
banners or little markings everywhere with reg jackets and colors and
bands is not going to make it safer - it is going to make it a mess. I
know that Jarrod Jablonski, in his trainging agency, GUE ( Global
Underwater Explorers ) uses the WKPP method, as he should , he helped
develop it and uses it in all of his diving.
Part of what makes a great system like this work is the ease of
working it, and the perceived benefits thereof. The GUE/WKPP method
requires doing nothing that takes you out of your way at all - it is
just there, and provides so many solutions. Long drawn out convoluted
sytems break down in action and never work underwater, and in the end
get discarded or poorly observed. This one is not only easy to do right,
it is self-correcting in that it only falls together one way - you
either do it or you do not know what you've got.
Efforts to complicate and "technify" diving make it more dangerous.
Try a little simple logic.
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