MT Imperial Encyclopedia: the basic TL9 Portable life support system is a Cr3000, 7 kg, 11 liter volume pack with two standard tanks that lasts you 4 hours. Those two tanks, under the label, "Oxygen Tanks", are TL5 basic 5 liter 2.5 kg Cr500 tanks. By simple math, each tank supports you for two hours.
Quick fact: pure oxygen at anything over about 0.3 atmospheres is dangerous, can cause injury, even lethal injury. Not a major problem: we drop the pressure in the suit. It's actually easier to move around in them that way - that's what NASA does.
Quick math: a person takes in about 6 to 9 liters of air a minute,depending on his level of exertion. At 21%, that translates as about 1.2 to 1.9 liters of O2. We don't use all of it: when we take in 6 to 9 liters of air at 21%, we breathe it out at about 16% O2 and 5% CO2.
So, let's say you're suit's inflated to 30 percent pressure of O2, and you're actively breathing at 1.9 liters per minute for 120 minutes: 228 liters unless you've got a way to filter CO2 and recover some of that unused oxygen you're breathing out. 228 liters in a 5 liter tank. Pressure is - 45.6 atmospheres? Did I do that right? 670 psi, the old fashioned way?
But I've seen tanks at 1900, 2200, even 2400 psi. Why are we so badly underfilled? Is it the business about being surrounded by vacuum?
NASA, according to these folk (it's a children's science page, but the numbers are good, I think):
http://quest.arc.nasa.gov/space/teachers/suited/9d6o2.html
run primary tanks filled to 5,860.5 kilopascals pressure. That's 58 atmospheres, 850 psi, almost 30% higher than what we're doing but still a whole lot under what some of the terrestrial tanks can store. They use it with a recycling system that cleans out the CO2 and lets the unused oxygen be re-used, which gives them 6 to 8 hours on 0.55 kilograms of oxygen (I think that's around 414 liters at room temperature). On the other hand, their secondary tank runs to 7 times as much pressure, around 6000 psi, though it can't support them as long because apparently it can't use the recycling system. (Though I'm not seeing how 1.19 kilograms of oxygen in the secondary only lasts them half an hour. I'm getting something wrong.)
Nasa's newer shuttle space suits are newer than Traveller. Did tanks in the 80's top out around 700 psi? Or did I screw up the math or make a mistake somewhere else? Occurred to me that they might be delivering plain-old air at 1 atmosphere - solves some problems in using them on worlds with exotic atmospheres, but it makes the suit a lot harder to move in. On the other hand, this is a TL9 suit - maybe they solved that.
Quick fact: pure oxygen at anything over about 0.3 atmospheres is dangerous, can cause injury, even lethal injury. Not a major problem: we drop the pressure in the suit. It's actually easier to move around in them that way - that's what NASA does.
Quick math: a person takes in about 6 to 9 liters of air a minute,depending on his level of exertion. At 21%, that translates as about 1.2 to 1.9 liters of O2. We don't use all of it: when we take in 6 to 9 liters of air at 21%, we breathe it out at about 16% O2 and 5% CO2.
So, let's say you're suit's inflated to 30 percent pressure of O2, and you're actively breathing at 1.9 liters per minute for 120 minutes: 228 liters unless you've got a way to filter CO2 and recover some of that unused oxygen you're breathing out. 228 liters in a 5 liter tank. Pressure is - 45.6 atmospheres? Did I do that right? 670 psi, the old fashioned way?
But I've seen tanks at 1900, 2200, even 2400 psi. Why are we so badly underfilled? Is it the business about being surrounded by vacuum?
NASA, according to these folk (it's a children's science page, but the numbers are good, I think):
http://quest.arc.nasa.gov/space/teachers/suited/9d6o2.html
run primary tanks filled to 5,860.5 kilopascals pressure. That's 58 atmospheres, 850 psi, almost 30% higher than what we're doing but still a whole lot under what some of the terrestrial tanks can store. They use it with a recycling system that cleans out the CO2 and lets the unused oxygen be re-used, which gives them 6 to 8 hours on 0.55 kilograms of oxygen (I think that's around 414 liters at room temperature). On the other hand, their secondary tank runs to 7 times as much pressure, around 6000 psi, though it can't support them as long because apparently it can't use the recycling system. (Though I'm not seeing how 1.19 kilograms of oxygen in the secondary only lasts them half an hour. I'm getting something wrong.)
Nasa's newer shuttle space suits are newer than Traveller. Did tanks in the 80's top out around 700 psi? Or did I screw up the math or make a mistake somewhere else? Occurred to me that they might be delivering plain-old air at 1 atmosphere - solves some problems in using them on worlds with exotic atmospheres, but it makes the suit a lot harder to move in. On the other hand, this is a TL9 suit - maybe they solved that.
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