Where did all the air come from!

[Gray Pennell]

I am thinking over a scene for my story. Someone is going to go into space combat and I am see them putting on the vacsuit and venting the atmosphere. Now the question that comes to mind is where does all the new atmosphere come from. Would it come from the "month" of life support? In a closed system once its gone its gone.

Help me with my silly question please

 

[far-trader]

Compressed in a part of the LS system.

Venting is a waste and pointless if you're talking the "SOP before combat to prevent explosive decompression in the case of a hit" line. If you can store it all it's still a questionable waste of time. Who's to say the storage won't be hit and not only will you lose ALL the air, it will probably do so causing much more damage. Better to have the vacc-suit in case of breech, but leave the air and make sure all compartments are sealed. Then if you are holed all you lose is the air in one compartment, and that slowly enough that damage control can probably patch it and save much of the air, if they can find the damage quickly enough and it's not too bad.

There might be tactical reasons or certain circumstance when you want to vent/compress all the air aboard and put the ship in a vacuum state. Rare reasons and circumstance imo. Very rare. So rare that they are not likely to have been planned for when constructing the ship so it won't be simple, fast, or easy.

Also I'd limit the amount of capacity for storing compressed air depending on the number and size of airlocks, which are the routine facility for doing so. Most ships will be able to indefinitely cycle the airlocks, but not much more beyond that. And air lost will be lost until replaced. So, how much airlock capacity does the ship have? Freighters might actually have quite a lot to cycle the large cargo airlocks. Ships with carried craft and vehicles likewise. However, if all you've got are a few (or one) small personnel airlocks that's not much cycle capacity.

 

[Enoki]

I would add one point to that. If you had a few compartments damaged and vented once repaired you could simply use the remaining air to ventilate them at a somewhat reduced air pressure. So long as the air pressure stayed above about 11 psi or so it would be acceptable. (ie the difference from sea level to a mountian top or so).
If the ship had a fuel processor plant in operation there is no reason they couldn't convert on board water to oxygen also to replenish the supply to some degree. Of course, that is limited by the crew's need for water.

 

[BytePro]

Yeah, venting is utter rubbish... even for fighting fires, one would simply purge the atmo of O2. Can see suiting up in an emergency combat pressure suit and reducing pressure (to avoid decompression) prior to expected engagements. IMTU, intentional 'venting' means removing the atmo to onboard storage (i.e. via the LS vents). Full exposure to vacuum for any duration means some level of damage to non-mil spec internal components (out gassing) and is not generally recommended.

LS would be an integral, distributed part of a starship - the walls themselves would contain hundreds, or thousands of independent, self powered, high pressure micro-tanks and pumps that could near instantly adjust pressure.

Making O2 is very easy - the powerplant would do this as a matter of course (assuming O2 is not needed from water).

In addition, O2 is safely stored for in emergency chemical (solid fuel) oxygen generators as have been used for decades (if not over a century?). [Airline oxygen uses perchlorate, IIRC - and ISS emergency 'oxygen candles' provide for a day per person...]

Normal atmo is 14.7 psi (ISS is kept at this - note U.S. space suits operate at about a third this, and mostly O2, IIRC - hence space walks require hours to acclimate to avoid nitrogen bends). Most of this pressure comes from a mostly inert gas as an O2 rich environment would be too dangerous - so maintaining 78% nitrogen blend would be the norm. This would be in compressed/liquid form as per O2 in micro-tanks.

In a typical worse case scenario, IMTU, one ends up on a low pressure O2 rich environment - which means rescue procedures involving compression chambers...

 

[Gray Pennell]

Thanks all, I thought something was wrong with this. So suit up but keep your air for as long as you can because its going to be while to get it back again if ever.

 

[BytePro]

IMTU, GG fueling generally results in topping off LS Nitrogen (split from Ammonia), and wilderness (water/ice) refueling topping off O2 (split from water). LS distributive nature and efficient recycling generally means no real crisis - as reserves will last a long time, even in the event of full decompression.

Never used it, but resorting to a low-pressure 'pure' O2 environment, like a spacesuit, could present interesting challenges - bends, fire potential, O2 toxicity, etc. However, unless the PCs are all simple grunts, they are going to have some minimal knowledge in these regards (even if the Players don't).

In RL, there have been a number of LS failures that one could borrow from, but such 'hard sci-fi' is 'believably' just icing in a 'star-faring' setting, unless one is going for near-future type games or pure space opera.

 

[HG_B]

In RL, there have been a number of LS failures that one could borrow from,

That wouldn't work for most games as very few play TL 6 or 7, Trav interstellar scenarios. Be kind of like borrowing RL naval disasters from 2000 B.C. while playing a game with 21st century U.S. naval ships...

 

[BytePro]

That wouldn't work for most games as very few play TL 6 or 7, Trav interstellar scenarios. Be kind of like borrowing RL naval disasters from 2000 B.C. while playing a game with 21st century U.S. naval ships...

Yeah - that's what the rest of the sentence said...

 

[Fritz_Brown]

If the ship had a fuel processor plant in operation there is no reason they couldn't convert on board water to oxygen also to replenish the supply to some degree.

Only problem there is increasing your partial pressure of oxygen too much could be dangerous. You need the inert gases and such in your atmo.

 

[BytePro]

Yep.. covered that.

 

[aramis]

Only problem there is increasing your partial pressure of oxygen too much could be dangerous. You need the inert gases and such in your atmo.

as long as you're below 300mBar, only for long term. And below 100mBar, the only one you can afford is CO2.

Also... aside from the head and lungs, you don't need air... just pressure. Mechanical counter-pressure is plenty fine, according to recent work.

 

[Fritz_Brown]

Yep.. covered that.

By gum, you did!

 

[Enoki]

Yeah, venting is utter rubbish... even for fighting fires, one would simply purge the atmo of O2. Can see suiting up in an emergency combat pressure suit and reducing pressure (to avoid decompression) prior to expected engagements. IMTU, intentional 'venting' means removing the atmo to onboard storage (i.e. via the LS vents). Full exposure to vacuum for any duration means some level of damage to non-mil spec internal components (out gassing) and is not generally recommended.

LS would be an integral, distributed part of a starship - the walls themselves would contain hundreds, or thousands of independent, self powered, high pressure micro-tanks and pumps that could near instantly adjust pressure.

Making O2 is very easy - the powerplant would do this as a matter of course (assuming O2 is not needed from water).

In addition, O2 is safely stored for in emergency chemical (solid fuel) oxygen generators as have been used for decades (if not over a century?). [Airline oxygen uses perchlorate, IIRC - and ISS emergency 'oxygen candles' provide for a day per person...]

Partially venting a space in a fire would be sufficent. Once you lowered the O2 content below that necessary to sustain the fire it would go out. So, a reduction is all that is necessary not going to a full vacuum. The other big reason to vent is not fire per se but smoke. This could easily be toxic and depending on what was burning, it could be thick enough to impar vision, cause respiratory problems, etc. So, on that count one might want to just dump the smoke and atmosphere overboard particularly if it can be replaced.

 

[BytePro]

IMTU, fire control is done with partial displacement of O2 using Argon. Smoke is handled by this the instant elimination of combustion and by filtration - as LS needs to be able to handle isolation of contaminates normally.

People can still breathe in an O2 reduced, argon rich environment - normal heat (retained by humidity in atmo) isn't ditched to space nor are the harder to replace non-O2 gases (nitrogen) dumped. This is also better for equipment (think RW server room fire suppression systems).

'Venting' to partial vacuum would route any fire following the O2 and would require routing to the exterior for every internal space with vacuum rated ducting and/or venting large portions of a ship. Further, it would spread any contamination along these surfaces. A huge and hard to clean up mess, not to mention it requires a lot of automated mechanical systems. I.e. one doesn't want involuntary venting going on when duct systems fail or non-computer hacking (i.e. lighting a match ) opens all the hatches because they all need automatic fail-safes to make a 'venting' to space system work efficiently.

Traveller is fundamentally written as Space Opera - venting to space sounds cool, but is a science fail. When I first began designing ships at age 12, I wanted really detailed plans - including handling 'venting'. Putting some thought into this led me to learn more science and coming up with ways of handling LS.

 

[Fritz_Brown]

Venting for a fire might be appropriate if it's a huge, rapidly expanding fire - and you have a way to vent rapidly. In most of my ship designs the engine space could be rapidly opened to space in an extreme emergency. Nothing else could really rapidly vent, but the engine space gets special attention.

Now, the real question is, what happens if you have to vent the engine space while in jump?

 

[Enoki]

IMTU, fire control is done with partial displacement of O2 using Argon. Smoke is handled by this the instant elimination of combustion and by filtration - as LS needs to be able to handle isolation of contaminates normally.

People can still breathe in an O2 reduced, argon rich environment - normal heat (retained by humidity in atmo) isn't ditched to space nor are the harder to replace non-O2 gases (nitrogen) dumped. This is also better for equipment (think RW server room fire suppression systems).

'Venting' to partial vacuum would route any fire following the O2 and would require routing to the exterior for every internal space with vacuum rated ducting and/or venting large portions of a ship. Further, it would spread any contamination along these surfaces. A huge and hard to clean up mess, not to mention it requires a lot of automated mechanical systems. I.e. one doesn't want involuntary venting going on when duct systems fail or non-computer hacking (i.e. lighting a match ) opens all the hatches because they all need automatic fail-safes to make a 'venting' to space system work efficiently.

Traveller is fundamentally written as Space Opera - venting to space sounds cool, but is a science fail. When I first began designing ships at age 12, I wanted really detailed plans - including handling 'venting'. Putting some thought into this led me to learn more science and coming up with ways of handling LS.

If the electronics are on fire they are already finished working-wise. It really won't matter at that point how you put it out. The whole point would be putting it out. The smoke from an electrical fire is probably the bigger hazard being particularly toxic usually.

 

[HG_B]

Now, the real question is, what happens if you have to vent the engine space while in jump?

Nothing because, only those with Eng. -2 would vent when they can just recompress.

 

[BytePro]

If the electronics are on fire they are already finished working-wise. It really won't matter at that point how you put it out. The whole point would be putting it out.

Not really.

Can't see space systems not being inherently redundant as in RL ... not to mention more than one system in a compartment.

In RL, I've witnessed more than one electrical fire (and many more overheats) that did not result in total equipment failure. In two cases, actual fires did not even interrupt operations (equipment supported isolation and hot swapping - literally!).

The smoke from an electrical fire is probably the bigger hazard being particularly toxic usually.

Certainly. And in the case of a closed environment, filtering is required to remove such contaminants. Stopping the source being highly recommended, of course.

The ISS experienced smoke release from an overheated O2 generator back about 6 years ago - the SOP is certainly not to vent the ISS!

Rather, respiratory gear is donned and filtering used to remove the toxic smoke.

For fantasy space opera - what with gravitics, 'uplifted' house pets and psionics - 'ventings' not really a major 'stretching believability' issue. But, IRL venting is utter rubbish. It would be a last resort in only very special situations and largely restricted to cockpits, cargo holds, bays, and airlocks - and reasonably not something that could be done without overriding multiple fail safes (or punching holes in the ship).

 

[far-trader]

...(or punching holes in the ship).

Which conveniently is what the combat, that might produce the fire, will do for you for free, and handily located in the very compartment that is on fire*. So again, venting, pointless. Let the enemy do it IF they hit and create the need for venting the compartment

Nobody prior to engaging in a wet naval battle scuttles their ship to avoid being sunk or prevent fires from being hit in combat

* I should probably have said "probably" there. Could be your ship is built like Starfleet ships where hits to any part of the ship will result in bridge consoles blowing up and catching fire What the heck, do they load them with little explosives rigged to detonators primed by various other areas so the crew on the bridge can "FEEL" the damage to the ship? :file_22:

 

[DangerousThing]

There's an easier way to deal with fire on a Traveller ship. If possible, set the gravity of that area to zero and cut the vents. Fire needs new oxygen in order to keep burning and in the absence of gravity and wind, the fire will die.

Then you cool it down before you bring the system back on line or else the fire will probably restart.

As for Star Trek consoles, that's always bothered me. I wish they'd just wire the Captain up to the various systems so that he'd know thw condition of the ship by what hurts,