[ Update 11:14 ]
The crew, as trained, closed the hatch linking the international section of the ISS and the Russian, isolating himself in the latter. From this position of safety will continue the analysis of the situation in the evacuated.
The crew is obviously trained to handle this type of emergency, this is what he told the Italian astronaut during addestamento in his diary:
“More than a fire and depressurization, the scenario that requires an immediate response without jokes is a loss of ammonia in the cabin. If you are wondering where quell’ammoniaca may be, here is a bit ‘of basic information on the design of ISS. All equipment we have on board generates a lot of heat, which we must free ourselves somehow. That is why we have cooling lines that run along the entire station: through the cold plates and the heat exchangers of the cabin, the water in those pipelines gathers heat. In pipes have heat exchangers interface, in which the heat is transferred from the cooling lines internal to the external. And in the latter, you guessed it, we ammonia. Two external pumps ensure that quell’ammoniaca flow from the heat exchangers, which collects the heat load, to the large coolers of the Station, where the heat is rejected into space.
So, now you know that there is an interface between the pipes outside of ammonia and water piped internally. What happens if there is a break in that interface, the heat exchanger? Well, since the pipes are external to a higher pressure, it is likely that ammonia would flow into the cabin.
Ammonia is highly toxic and has a very characteristic odor. However, if the loss is small enough, the system autosensing of the vehicle or the ground control may notice it first, by observing an increase in the amount of fluid in the accumulator of the cooling system: since we’re not adding any water, an increase in amount must come from ammonia. From the diary known L-142
“Because ammonia is highly toxic, the first action is to wear an oxygen mask. All along the ISS have at least a mask, often two, in each module, ready to be used. The masks of the US segment have a small tank containing a reserve of 7 minutes of oxygen. It may not seem like much, but these masks are used only for the initial response, as you will see.
With the masks worn, those of us who were in the segment USOS (USA more modules Columbus and JEM) have moved rapidly aft towards the Russian segment-not only because our Soyuz vehicles are hooked there, but also for a major design difference: there are no ammonia pipelines in the Russian segment.
Making sure you know where are all six crew members, we close the door of Node 1, thus isolating the segment USOS and the source of the leak. At that point we get rid of the outer layer of clothing, potentially contaminated, and leave them in the PMA, the small adapter element between the segment and the Russian USOS, closing the door aft of PMA while we retreat to the Russian module FGB.
It is time to recover our masks with respirator and climb aboard the cartridges pink with filters for ammonia. The transition from the O2 breathing masks for ammonia must be done very quickly and carefully, because we do not know what is the concentration of ammonia in the atmosphere of the Russian segment. Assuming that the contaminated atmosphere, keep your eyes closed and hold our breath while we remove the masks O2. Once worn respirators, we make a number of breaths of purification to rid ourselves of any ammonia inside the cap. Only then re-open eyes.
After that everyone is safely passed on to the respirator, it’s time to figure out how much we have ammonia in the atmosphere of the Russian segment. For that we have a measurement system with dedicated chip. In the worst scenario, the Russian segment is contaminated to a level that we have to evacuate the station. If the ammonia concentration is not so high, we can filter the air through our cartridges respirator through breathing. Then we stay for several hours, until the measures show a safe atmosphere. If lucky when the air in the Russian segment had not been contaminated, we could remove the mask and breathe normally. Safe, of course, but with the segment USOS lost, at least for the moment. From the diary known L-140
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