Dave Hill <email@example.com>
I read an interesting piece by you on oxygen quality of your products. You mentioned the importance of the water content in the gas. Can you please tell me the water content of Poisk oxygen? I have this as a request from a client going to Everest who may have read the same piece you wrote.
Presence of moisture in gases (oxygen among them) is characterized (or described) by the temperature of the dew point. If we cool air with usual to us humidity to 8 ˚Ñ – there will happen dew fall, thus in this case the dew point will equal to 8˚Ñ.
Amount of water vapours in the oxygen, that we are filling our cylinders with at 20°Ñ and 760 mm of mercury column (regular atmospheric pressure) must not exceed 0,005 g/l (gramme per litre), which corresponds to the saturation temperature (dew point) at 760 mm m.c. not above minus 63°Ñ. In other words it means that if oxygen in our cylinder would have been under such pressure (approx. 1 bar) and we would have frozen it to minus 63°Ñ, then there might have formed droplets of moisture but most probably – ice crystals due to very low temperature. Well, if we freeze our cylinder to a temperature below minus 183°Ñ at atmospheric pressure, then the oxygen itself will become liquid. Usually moisture content in the oxygen inside our cylinders varies from 0,003 to 0,004 g/l under atmospheric pressure.
But the oxygen in the cylinder is compressed to a certain pressure which may vary contingent on the ambient temperature and its flow via the pressure regulator to the climber’s gas mask. In the new 4-litre cylinder oxygen is compressed approximately 300 times (around 1200 litres), in other words it contains no more than 6 (usually 3,6-4,8) grammes of moisture.
But usually those are not the oxygen cylinders that freeze but the pressure regulators. Mechanism of freezing is quite simple: while expanding in the regulator the oxygen cools (like Freon in the refrigerator). One can calculate approximately, that if a regulator reduces pressure by 1 bar it results in cooling by 0.25˚Ñ (this value depends upon flow rate set onto the regulator and ambient air temperature).
Freezing of a gas mask is completely different. Here the reason for icing of the valves and other mask’s elements is – condensation of moisture due to high concentration of its vapours in the exhaled air and instant temperature drop (from body temperature +36,6˚Ñ to the temperature of the ambient air minus 20˚Ñ and below). Besides, main task of the climber’s gas mask is to heat and moisturise cold and dry oxygen from the cylinder by means of its mixing with the exhaled air, otherwise hypothermia and drying out of respiratory tracts are possible.
Can you please tell me what percentage of oxygen is used for climbing.
For example, normal air we breath is about 21% oxygen, but hospital grade oxygen is about 93%.
What is the percentage for climbing?
With kind regards and thanks,
First of all some information about breathing as such. It is considered (accepted) that an adult human consumes (eats) around one kilogramme of oxygen (O2) per day or 900 liters at normal atmospheric pressure.
At this time, when being at ease, a human performs 14 inhales per minute in average, air-flow via lungs is around 6-9 liters per minute (oxygen consumption is - 0,25-0,30 liters per minute). Under conditions of physical stress per minute volume of breathing may reach up to 120 liters per minute (oxygen consumption - 5-6 litres per minute). Beyond doubt that air which we breath at sea level is the best environment for our body, it contains around 20,9% of oxygen and its partial pressure constitutes around 159 mm of mercury column, it contains almost no CO2. In the exhaled air there are only 17,5% of oxygen and CO2 content is around 3,5%.
Under normal conditions, at sea level, concentration of oxygen in the air is higher than it is in the blood, and because of that oxygen via a thin layer of air vesicle in the lungs is transferred into the blood. And vice versa, concentration of CO2 in the atmosphere is ever lower than in the blood and because of that flow of CO2 is reverse to the flow of oxygen from the lungs into the atmosphere.
But with elevation concentration of oxygen in the air (its partial pressure) drops approximately in the same way as drops the ambient pressure, at elevation of mountain Everest it is almost 3.5 times (see attached picture).
Respectively there arises a necessity to compensate these losses via supply of additional oxygen into the inhaled air and CO2 for stimulation of the breathing activity. For fighting hypoxia (mountain sickness) it is most effective to use for breathing a mixture of 93-95% Î2 and 5-7% ÑÎ2. All this occurs in the climber’s gas mask by means of mixing of exhaled air, depleted of oxygen but enriched with CO2, with pure oxygen, which is supplied from the cylinder. Using regulator it is possible (dependent on the general well-being) to adjust air-flow of oxygen from the cylinder into the gas-mask. Thus, there is no great difference if oxygen purity in your cylinder will be not 100%, but e.g. 93%. The only impact will be an insignificant increase of air-flow from the cylinder into the gas mask. One must remember though that outstanding 7% might be very dangerous for the climber additives – e.g. water vapours, which can easily freeze under negative ambient temperature in the pressure regulator or in the cylinder’s nipple and damage it for good.
In Russia and in our company there exists a standard according to which purity of oxygen in our cylinders must be 99,5% minimum. More rigid standards envision oxygen purity up to 99,999 % (TU 2114-001-05798345-2007). But oxygen of such purity is rather expensive and there is no sense to use it for climbing.
Mrs. Kluinina Zoya
Hi There, I was on your website and have a question about your oxygen cylinders.
You mention having different categories of cylinders-A, B, etc. Is the plastic packaging sleeve the same with category A and B or is it different?
Is the packaging clear or colored and if colored, what color.
Sincerely, Willow Healy
Dear Mr. Healy,
Our cylinders, dependent of their purposed pressure and location, where they were filled (refilled) are being divided into several groups À, Â, Ñ and D (detailed description see on our web-site - http://www.en.poisk-ltd.com/publication/componynews/componynews_23.html). Respectively each group has its own marking and plastic packing (sleeve).
Cylinders from groups A and B should be filled (refilled) with oxygen up to the pressure of 340 bar at the temperature of +50˚Ñ (300 bar at Ò = +20˚Ñ). These cylinders are called POISK-OS, and on their surface they have the same thermoplastic packing (sleeve):
Cylinders of group A differ from the cylinders of group B only by the marking of the cap on the stopping valve:
Cylinder filled in Russia
Cylinder filled in Kathmandu
If your cylinder has such marking and it is intact that means that this particular cylinder was filled by us in Russia and that it has no less than 1625 grammes of medical oxygen (group A). If we were filling (refilling) it in Kathmandu at our refilling station (pressure and weight of the refill are the same, but oxygen is delivered from India and it is impossible for us to have full control over its quality), then we attach a holographic sticker to the cap (group B).
Besides, factory packing of cylinders using special scotch tape looks like this:
Cylinders from groups C and D (refilled by us in Kathmandu after being used) will have the following thermoplastic packing (sleeve):
Dependent upon their date of manufacture such cylinders can be refilled up to the pressure of 300 bar at T = +50˚Ñ (260 bar at T= +20˚Ñ) for group D and up to 320 bar at T= +50˚Ñ (280 bar at T= +20˚Ñ) for group C. Such cylinders POISK refills only in its representative office in Kathmandu. In this case the cap of the stopping valve will have no marking. On the thermoplastic shell of the cylinder by means of print there will be indicated marking of the group (C or D), actual (de facto) pressure (bar) to which the cylinder was filled and mass of oxygen in the cylinder (grammes).
If the cylinders have no such abovementioned marking or it was damaged (tampered with) – this means that these cylinders were not filled by POISK and we can’t warrant their safety and reliability.
We wish to you successful ascents and all the best.
Zoya Klunina, Director
Dear, Mr Schatzl,
Thank you for your letter.
We also know that our bottles are refilled in India and Nepal. So we always inform our customers that this refilling is very dangerous for those people who use these refilled cylinders during their climbing in the mountains.
The problem is that no one never controls quality of oxygen not in India nor in Nepal, so no one will ever tell about the quality oxygen that was pumped into the cylinder. As per Russian standards’ requirements purity of oxygen in the cylinder should be not less than 99.5%. In Russia at our production facility after filling of a batch of cylinders (this is a quantity of cylinders filled during one working shift) we always take one random cylinder and take a test sample of oxygen from it. If oxygen purity is more than 99.5%, then such cylinders are sent to the client, if it is less then stated amount, such cylinders will be bleeded, the cylinders will be carefully washed and then refilled.
In addition, it is necessary to control purity of all pipelines and valves in the filling system. These systems are periodically washed and cleaned and special filters are installed.
The biggest danger for a human is not in the fact that the percentage of oxygen may be less than 99,5% because the man during breathing would hardly feel the difference between 99.5% and, for example, 99% or even 90%. The real problem is in the fact that dirt particles or frozen moisture in the form of pieces of ice can get into the shutoff valve of the bottle and it may be damaged or, which is more dangerous there might occur ignition when connecting the regulator to the cylinder’s valve.
As far as we know about accidents or failure of the shutoff valves in the cylinders that took place in Nepal or India, they were all related to the fact that after refilling dirt from the injected oxygen got to the bottle’s valve or the valve was broken because of its wrong connection to the filling trunk of the compressor.
Due to bad quality of oxygen in Nepal, now we refill the cylinders in Russia, only. We can deliver these filled cylinders to any point of the world. Everything depends only on a possibility of customs clearance of a dangerous cargo in the country of destination.
Zoya Klunina, Director