Essay: Oxygen on Everest
Eric Simonson - Basecamp
Fri, May 04, 2001 4:45AM

Oxygen apparatus used on Everest has changed a lot over the years. The debate that the British started back in the 20's and 30's has not. Is it "fair" to climb with O2? Well, in my estimation, it depends on the game you are trying to play. Some exceptional climbers, like Ed Viesturs, who I have tremendous respect for, are strong and experienced enough to climb without supplemental oxygen. Their success depends on their ability to climb quickly and minimize their time in the "death zone". Other climbers can't climb at this level of performance, or don't want to take the risk of brain damage and the diminished margin of safety from going without oxygen. For them, it's a different game. They might just want to get to the top safely and have fun. There is still another group of climbers who do not have the strength and experience to climb without O2 but who try to do it anyway, and often get into terrible trouble up high. I'm sure we'll see several deaths this season of people who "swim so far out into the ocean that they can't make it back to the beach". It's especially a problem on the North Ridge, which is hard to get down, especially when you are tired or wasted.

For years we have brought our cylinders home for re-filling. It makes sense from the standpoint of economics and aesthetics. The bottles are expensive. Plus, no one wants to look at trash on the mountains. It used to be that there were a LOT of old bottles on Everest. Over the last few years, most of them have been carried down. In fact just last week, I tried to get our Sherpas to carry down some souvenir bottles on their way down from a carry to Camp 6, and they couldn't find any! They have all been grabbed by souvenir hunters and clean up expeditions. The same thing goes for the south side, where there used to be more than 1000 bottles on the South Col. They are almost all gone now. I remember in 1998 we were paying our Sherpas $15 a bottle to carry them down, and one Sherpa brought down 7 at one time!

Climbing with oxygen is still difficult, in part because you have to carry the cylinders. It's not magic. More than anything, it keeps you warm and your brain alert. I used to like it because I could actually look around and enjoy what I was doing. For our search climbers, who are staying up high for a long time, its important to have O2 available, especially when sleeping at such high altitude. During the night your breathing rate slows down, and its common for climbers to become hypoxic. We usually sleep on 1 liter per minute. During the day, most climbers will use 2-3 liters per minute, depending on how hard they are working and how much O2 they have! We could debate oxygen use for a long time, and that is not my goal here. Rather, I wanted to say a few things about the physical changes that have taken place over the years the gear itself.

Up until the early 1960's, most of the cylinders used were solid steel. They were not very efficient, since they were not capable of high pressures. Plus they were heavy for their volume. The 1922 cylinders held 240 liters at 120 atmospheres. In 1924 the British used a bottle that held about 535 liters, again at 120 atmospheres. In 1938 the British used a bottle that held 500 liters at 120 atmospheres. The 1960 Chinese cylinders were made in Germany and held 400 liters of oxygen at 200 atmospheres but weighed nearly 20 pounds, complete with regulators!

In the 1960's expeditions started using a bottle made in France that was aluminum, wrapped with wire, which held 920 liters at 230 atmospheres. These were used by both the Americans in 1963 and the Chinese in 1975 (a few of these French bottles were used by the Chinese in 1960 for their summit bid, at 170-180 atmospheres). These bottles were stronger and lighter, and were capable of higher pressures, and could thus hold more oxygen. In the 80's climbers started to use aluminum cylinders wrapped with fiberglass, which provided additional strength. By the 1990's cylinders were being wrapped with Kevlar, which was stronger than fiberglass. Now we are using aluminum cylinders wrapped with carbon fiber, which is even better. The cylinders our IMG teams use on Everest and Cho Oyu are made by the American company Structural Composites Industries, and hold 1850 liters at 3000 psi (about 200 atmospheres). Also popular among climbers are cylinders made in Russia by the companies Poisk or Zvesda. These are typically smaller cylinders (volumes of 3-4 liters) filled to 260-320 atmospheres or so.

In the USA it is not legal to fill oxygen to over 3000 psi (about 200 atmospheres). It is possible to buy cylinders in the USA that will hold 5000 psi (these are used by firefighters for their airpacks...not O2). In other parts of the world (like the UK and Russia) it its possible to get cylinders like these filled to higher pressures. In the USA, the Department of Transportation regulates the legal transport of cylinders. If you want to ship them on an airplane, then 3000 psi is all you can get. This is not so bad, however, because the high quality carbon fiber bottles now available are quite light and hold a tremendous amount of oxygen. Plus, you know what you are dealing with in terms of a commodity that is regulated at every phase. I ship my cylinders home after each expedition, have them hydro-tested, chemically cleaned, re-valved with new burst disks, re-filled with dehumidified oxygen, packed in DOT approved containers, documented by a licensed dangerous goods handler, and legally shipped back to the Himalayas. It's all a big pain, but when you crack the bottle at 25,000 feet, its nice to know what you are getting.

Eric Simonson, Expedition Leader

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