Is it safe to carry Butane canisters bought at sea level up to 5500m?

Question

I am planning a trip to the Everest Base Camp in a few days.

I am planning to carry with me a portable stove and 4 Butane Canisters, to make soup and stuff.

About Butane Canisters:

1. These are bought at sea level. Would they be safe to carry at altitudes of 5500 meters? Do these things explode at high altitude?

2. What is the safest way to pack gas canisters, and where in the rucksack should they be put (I would not like to have them near the head and the spine, but that's where the Rucksack usually is.)

Answer 1

1. Yes, they are safe at this altitude. I don't know the maximum altitude, but the atmospheric pressure at 10,000 m (higher than Everest at 8848.1 m) is approx 26.4 kPa, which is about 1/4 of that at sea level (generally defined as 100 kPa). At 5,000 m this is about 55 kPa. Neither of these is a problem for the canister itself to contain, though you can get an overpressure situation which might result in some leakage from the valve. You won't get a catastrophic failure with shards of metal or anything.

   Thanks to @JonCuster for the comment. The reason this is so is because they are designed to withstand heat. As the temperature increases, the gas expands and creates greater pressure. Most manufacturers seem to recommend storage below 50 C (120F) because the pressure increases the risk of canister failure. At room temperatures the pressure is about 2-3 atmospheres and increases as the temperature goes up. The canister is engineered to contain the pressure at 50 C, which is a massive compared to the difference in pressure between sea level and 5500 m altitude.

   However, you have bigger problems than pressure with butane at altitude, and that is temperature. Butane boils at about -0.5°C (31°F), which is only just below freezing. Isobutane boils at -11.7°C (11°F) and propane at -42°C (-43.6°F), so both of these will be a better choice than pure butane at altitude, especially when you consider that the canisters cool when gas is released.

2. Make sure the canisters don't get crushed - put them inside something like a cooking pan. These are usually strong enough to not get crushed, and have the added bonus of having your cooking materials all in the same place. Heavy stuff like cooking gear generally goes upper back, close to the spine. Inside a pan there is very little risk of accidental rupture.

Answer 2

The canisters are (hopefully) safe at sea level within any plausible temperature range. So, they shouldn't explode when reaching 50 °C.

The stress of the canister can be expressed as the pressure difference between inside and outside.

At 50 °C, the inner pressure created by pure butane is around 5 bar (500 kPa), and at sea level the outside pressure is 1 bar (100 kPa), so we can assume that the canister survives a 4 bar pressure difference.

Even if you were to "completely" leave the atmosphere (outer pressure zero), the pressure difference would only rise to 5 bar, and you could compensate for that by making sure the temperature stays about 10 degrees lower.

As most prabably, the temperature in high mountains is considerably lower than at sea level, don't worry about the canisters' safety. But (as Bob1 answered) they might be useless because of a lack of pressure.