Comment by SilasX
7 years ago
Yeah, but at the same time, it wasn't enough to set off the alarms for low oxygen content, which is at least a little disturbing, right?
7 years ago
Yeah, but at the same time, it wasn't enough to set off the alarms for low oxygen content, which is at least a little disturbing, right?
Not necessarily.
Nobody could adequately explain to those of us in the CS dept why we had to take 3 semesters of Chemistry. Bits of it hung on and from other sources such as space exploration articles I recall this much:
Fires and lungs both operate on partial pressure of oxygen. As long as nothing else in the air is toxic, your body cares that it gets X oxygen molecules per cubic centimeter of air in your lungs, not Y parts per million. Those deep sea submariners are breathing mostly helium with a small fraction of oxygen in it. If you just compressed surface air there would be so much oxygen that your hair would explode when you ran your hand through it. Assuming the electronics didn't burst into flames first. And if you didn't set yourself on fire, that much nitrogen would kill you pretty quick.
So the question is, does helium displace air or mix in with it? I believe the answer is 'some of both'. If that's the case (and I think we can infer that from "the alarms didn't go off") then a good amount of helium might reduce the oxygen partial pressure less than going to 3000 feet above sea level. So what's the Venn diagram of COPD sufferers, in a hospital wing near the MRI machine, that aren't currently on supplemental oxygen?
Moreover, helium floats to the top and escapes through any opening (staircases, HVAC ducts, gaps in ceiling tiles) because it is lighter than air. This makes it much less dangerous than a heavier gas such as CO2 even if there's enough of it to displace a significant amount of air.
Not just any opening: just about any microscopic crack would let it out and most non-metal materials are effectively porous when trying to contain helium under pressure. It's even used to detect leaks in high vacuum chambers.
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That is not true by any stretch of the imagination. If gases behaved like that then we'd all be choking on a layer of argon with all of the oxygen out of reach above us. No, gases diffuse and mix easily.
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Helium breathing mixes are for deep sea divers, not submariners. Most submarines run an interior gas mix nearly identical to regular air.
I didn’t mean navy boys, I meant research submarines at extreme depth.
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I assume the first two semesters were first-year (freshman) chemistry. What was the third year? Organic?
As long as there is enough oxygen in the air, what's disturbing about it? People breathe helium/nitrogen/oxygen mixtures all the time.
https://en.wikipedia.org/wiki/Trimix_(breathing_gas)
I didn't mean that the air would be dangerous to breathe.
I meant that it's disturbing that the amount of He needed to disable the iPhone is low enough that the standard sensors around He (which measure 02 levels) don't regard it as a major leak for He to be at that level.
Virtually all (esp. consumer) devices assume 'normal' atmospheric conditions with 'normal' temperature ranges and 'normal' humidity ranges. As you start to go outside those ranges, strange things can happen. People at extreme altitudes and/or in extreme climates see this on some types of devices. It's not a big deal. If you have needs outside the typical ranges, you provide your specifications and be prepared to pay much more for your solution.
Why would that be disturbing? Electronics and organisms do not have identical environmental tolerances/intolerances.
Presumably, the sensors exist to protect humans, not electronics.
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Helium, unlike carbon dioxide, is lighter than both oxygen and nitrogen, so it would rise in the rooms and be very unlikely to displace oxygen in people and set off any oxygen alarms.
In addition, unlike carbon monoxide, helium doesn't bind to, well, anything and certainly not hemoglobin, so it doesn't present a momentary exposure hazard either.
See other reply -- I wasn't referring to danger to humans.
What the heck? I clarified that I was concerned about the silent danger to the iPhone, not to humans, and people keep assuring me there’s no danger to humans, and giving me flack just for saying that wasn’t my concern? This is a weird thread.
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And nobody was talking like Donald Duck either so I would guess it was leaking out of the room at a pretty hefty rate.
Depends on where the sensors are located. If at head height, the helium may occupy the layer above and tall people would have a hard time.
Sadly, the plant used Apple's iSensors which don't work in the presence of helium.