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Everest oxygen, how the *$#! does this thing work?
Jul 5, 2004 14: 41 EST
While
most folks going to Everest have done their research about Oxygen, which
brand to use, how many bottles, how much to pay, how to get it there, etc.
. . they don’t learn the in’s and out’s of how to operated the system until
they get there and have the system in their hands to check out. This is
the most critical part, by far – it doesn’t matter how many bottles you’ve
gotten up to the high camps for a summit attempt if you don’t know how to
properly use the system.
Today we’re going to go over proper usage and the quirks of a system that is very common on Everest these days; Poisk.
First things first – the system is made up of three elements: The bottle,
the mask, and the regulator. The regulator take the high pressure from the
cylinder and steps it down to a rate that won’t blow your lungs out.
Setup is rather simple, but you’ve got be careful with a few certain
things. The air coming out of the bottle and through the regulator is at
a very high pressure, so you’ve got to careful when making the connection.
The Poisk bottles you plan to use for your climb should have protective
caps on top to keep the threads in good shape for the connection to the regulator.
Keep these on until you are ready to connect, but make sure that they’re
not so tight that you can’t unscrew them by hand.
When screwing the regulator on or screwing it off, you’ve got to have
the regulator turned on, or flowing. Some say a 2 Lpm (Liters per minute)
flow is adequate; others say the full setting of 4 Lpm is necessary. To
be on the safe side, just jack it up to 4 Lpm – you’re not wasting all that
much if you turn it off right after screwing it on.
Don’t blow it out!
Attachment is not as important as detachment, however. Why do you have
the regulator on for this process? Well, there’s a washer-type gasket in
the regulator that forms a seal with the cylinder – by having the regulator
flowing, you decrease the chance of blowing that gasket out. Should the
regulator’s washer (which is small, and white – making it very difficult
to find) blow out, you’ll have a leaky connection on the next bottle you
tap into. Always check inside the reg to ensure the washer is still there.
Should the washer get blown out and you can’t find it, we know of climbers
who have screwed through it and got a tight enough seal. This obviously
isn’t the way to use the system, but if you’re high up with a blown seal
you really don’t have much of a choice.
Don’t blow it up
The next thing to be careful of is of the oil on your hands. Oxygen
and oil do not mix well and can cause an explosion. Keep your hands away
from the threaded/connection area. Your hand oils coupled with the oxygen
and high pressure of the tank can cause an explosion, something you don’t
want to deal with high up.
Don’t flow it out
Now once you’re connected, you’ve got to figure out how long your oxygen
is going to last. There’s a little math here, so it’s good to think these
through before you start climbing with it. For Poisk, there’s two different
choices, a 3L bottle and a 4L bottle. Depending on the temperature, you
typically have anywhere from 250 bar to 300 bar with a fresh bottle. Your
regulator can dish anywhere from about ˝ a liter per minute, all the way
up to 4. Generally, you sleep on .5 to 1.5 lpm, climb on 2 lpm, and when
the going gets rough, jack it up to 4 lpm (This is just a general guideline,
flow rates are unique to each climber). So how do you figure out how many
O’s you have left?
A little math lesson
Ok, so a 4L bottle at 250 bar will have 1000 Liters in it; 4 multiplied
by 250 = 1000. If you’ve got 1000 L, and you are running at 2 liters per
minute flow: 1000 divided by 2 = 500 minutes of remaining time. 500 minutes
comes to 8 1/3 hours of use. So a new 4L bottle at 250 bar, running at 2
lpm flow will give you 8 1/3 hours of use. Because of leakage, connecting
and disconnecting, it’s a good idea to give a fudge factor of about an hour
or so. To be on the safe side, figure 7 hours at 2 lpm on a full 250 bar
bottle.
The formula is (Volume of the bottle in Liters) times (the bottle’s pressure
in bar) divided by (your rate of flow in Liters per minute) = the total minutes
you’ll have. This number you can divide by 60 (60 minutes in 1 hour) and
you’ll get how many hours you have. Then put in about an hour fudge factor
to be on the safe side.
Don’t blow your mask out
The way the mask is configured, it mixes the outside air with your oxygen.
A valve on the front forms a partial seal, so your breath takes in some
outside air as well as the oxygen from the tank. The moisture from your
exhalations, coupled with the downward tilt of your head (It’s hard to see
your feet over the mask, so you’ve really got to tilt your head to look down)
equals a bunch of ice built up around that valve. The ice can block the
valve, however, a bigger problem is when you try and break the ice away.
If you have enough buildup, you can actually feel the weight of it pulling
your face down. When you break the ice away it can pull that valve out –
in which case you essentially have a hole in the front of the mask. This
means you’re now breathing more outside air than cylinder oxygen. You’re
still getting oxygen, but not as much as if that valve was there. Take a
visual inspection, pull the mask away from your face and if you can look
straight through it, the valve is no longer there. Hopefully it popped out
inwards and you’ve got it in the mask chamber and can pop it back in.
Don’t drop it
The last and most obvious thing is to not drop your extra cylinders.
This seems like a no-brainer, but remember that at altitude you’re not as
careful, the bottles are round and missile shaped, and many Everest camps
are on a slope. Keep them clipped in somewhere and prop them on rocks.
A 4 L bottle of oxygen at high camp can run you in excess of a 1000 USD as
you have to figure in not only the cost of the bottle (around 350 USD) plus
what it cost to get it up there. So it’s not only an expensive mistake,
but a deadly one as well. This year the Russian North Wall team almost got
creamed by someone who dropped a bottle high up down on them.
Poisk Oxygen summary:
1. Always check that the regulator has a gasket – a white washer-looking thing inside the threads
2. When screwing or unscrewing the regulator to the bottle, always have
the regulator on 4 lpm (Once screwed on, immediately turn it off to conserve).
3. Keep your hands off where the reg and cylinder meet – the oils from your hand can cause an explosion
4. The rules of thumb for determining flow: .5 to 1.5 lpm for sleeping;
2 lpm for climbing; jack it up to 3 or 4 lpm for the more challenging sections.
The flow is dictated by how you are feeling and how many bottles you have.
People have done a whole summit push at 4 lpm, you just have to bring enough
bottles.
5. Determining the time remaining: (Volume of cylinder in liters) x
(Pressure in bars) divided by the (Rate of flow in lpm) = total minutes left.
6. When clearing ice off of front of mask, always check to see if that
valve in front is intact. If you don’t see it there, hope it fell in the
mask and you can pop it back in.
7. Don’t drop bottles
These are some guidelines to better help understand the usage of the
Poisk oxygen system. Climbers who have used the system previously have different
opinions about flow rates, etc. . . Before climbing, be sure to speak with
your expedition leader and read up as much as you can about the oxygen –
a malfunctioning system high up can result in disaster.
Image of another “don’t” courtesy of Serac Adventure Films – Don’t try
and light your stove in high camps by turning the oxygen on and placing the
mask next to the burner. Follow link to related story
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