There are primarily two brands used today: POISK and UK. We have used both (the UK are cheaper yet heavier) and prefer POISK. The sherpas always want POISK.
In 1999 we carried 15 UK bottles. 4 of them broke in the valve at C4 and couldn't be used. We were lucky to have enough spares, but as you would imagine, it could be fatal if it happened in the wrong place at the wrong time.
That year, we paid a visit to the POISK factory in St Petersburg and were impressed by their manufacturing procedure. Every cylinder is carefully tested under strict conditions. It is labeled with an individual license, stating the date of manufacture, content, weight, and other.
During our visit we discussed various problems involved in ordering oxygen. Some Everest veterans had claimed sole distributorship. It is now however possible for all climbers to order directly from the factory and POISK will arrange for the delivery to Kathmandu.
Get more information and place your order at www.poisk-ltd.ru/
The oxygen should be used within two years from the date of last testing.
There are not only pirate copies of Levis and Rolex around. Believe it or not - there are also fake POISK bottles out there. They are old POISK bottles, transported by truck to India and refilled at a fraction of the real cost, sold to climbers as the real stuff. The people at POISK have nothing to do with this.
We know for a fact that some commercial expeditions have advertised POISK to their clients, only to deliver the Indian fake version.
If you are not buying straight from POISK (or another brand), check with POISK (or other manufacturer) if the person you are buying from really have placed an order with them.
This foul trade is nothing less than making a dollar out of a gamble with people's lives. It is extremely dangerous and we hope that it will soon come to an end.
Don't get yourself into trouble by saving money on oxygen. Failing oxygen is a big cause of accidents on Everest. Bring plenty and bring the right stuff. You can sell your leftover oxygen back in Kathmandu to fall- and next years expeditions. And notify us on any foul business. Protect other climbers, please.