Doing some research and need a little information

[bassplayer]

Now back to my initial problem. I had read a real-life account from some years back about a man scuba diving in a flooded mine, who died inside an air pocket. I've heard of similar things happening in flooded caves. Its also been said that when Egyptian tombs were first breached the air inside was toxic. Again, difficult to get insights into all this without talking to people who've done it.


On the flip side, if you're telling me its reasonable that an airtight room, sealed off from the outside world for thousands of years but connected to a water source, should still contain perfectly breathable air, then I can just write the scene that way and run with it.

thousands of years, hmm.
I was told in some science class once upon a time that air pockets in that condition would slowly shrink as the gasses dissolve into the containing body of water. sorry i don't know the rate of dissolution or whether the component gasses dissolve at different rates

 

[hunterjwizzard]

If you wanted to make it non-life sustaining, build it from iron. Rust is caused by the binding of O2 molecules from the air with iron. Eventually enough oxygen will be removed to make it deadly. This is a real problem in ship maintenance and especially ship scrapping. Lots of people have been killed entering sealed empty spaces.

Ahhh! Thank you kindly That's the part I've been trying to understand. I could definitely write around that as one option.

Note I said "life sustaining" rather than "breathable". You can breathe all kinds of gas mixtures that will feel just fine until you die from it.

Are there mixtures that would be "breathable" using the right type of gas mask, and if so what conditions would create those? If none make sense I'll probably need to give my protagonist an air supply.

 

[hunterjwizzard]

thousands of years, hmm.
I was told in some science class once upon a time that air pockets in that condition would slowly shrink as the gasses dissolve into the containing body of water. sorry i don't know the rate of dissolution or whether the component gasses dissolve at different rates

I have also been told this but only about air pockets actually beneath the water surface(EG flooded caves, sunken ships, etc). This is why the actual space in my story is above the water level. Its just the character can only get inside by swimming through a flooded entrance.

 

[johndiver999]

If the air pocket is above the surface of the lake, then that air space could easily exchange gas with the atmosphere if there were tiny cracks in the struture. The cracks or porosity of the rock could be so small that absolutely no light could penetrate, but gas exchange could occur. If the air space were below the surface of the lake then this gas exchange could not occur - because all the air would just leak out to the atmosphere. The air space in the structure the author is describing id similar to a beaver den, which can support life all winter - assuming the structure is not perfectly air tight.

A gas mask does not provide oxygen, which would be depleted to a very low level in an air tight chamber that communicated with a lake so a gas mask doesn't work in the originally described scenario,

 

[lowwall]

.. precisely what realistic measures my protagonist needs to take to not die. At present I have the character free-diving in, then putting on a gas mask, but somehow I don't think that's right. I'm hoping someone here can give me a better sense of this.

Thank you in advance!

I didn't respond to this part. You have to decide why your air is unbreathable before you can decide what action to take. A gas mask only filters out toxic particles, it won't help if there's insufficient oxygen or an excess of CO2.

If there's not enough oxygen, then a WW2-style oxygen rebreather would work and is reasonably compact. These aren't used anymore in recreational scuba because they use 100% oxygen which will result in convulsions and loss of consciousness If you breathe on it too long at depths below 20 feet. But it should be fine for your purposes. Special forces frogmen also still use these because they don't need to go deep, they release very few bubbles so are relatively stealthy, and they allow fairly compact while allowing long underwater swims

Rebreathers – Siel

www.sielnet.com

These are also in current use for mine emergencies so having your character obtain one wouldn't be too implausible. For example: M-20.3 Emergency Escape Breathing Device | Products | Ocenco

If you want something lower tech, then have the space be sustainable, but not that big. In this case CO2 buildup becomes the first problem. You can deal with this by spreading out materials that absorb the CO2 such as Sofnolime 797 and CD Grade for Commercial & Leisure Diving - Molecular Products

This would give you a working time of a couple of hours before the O2 levels got too low. You could remedy this with some sort of oxygen candle - Chemical oxygen generator - Wikipedia - or slowly adding 02 from a tank of picked up at a scuba, medical, aircraft, or welding supplier.

Got any firearms questions? That's my real area of expertise

 

[hunterjwizzard]

A gas mask does not provide oxygen, which would be depleted to a very low level in an air tight chamber that communicated with a lake so a gas mask doesn't work in the originally described scenario,

Awesome! Thanks for the explanation!

Now for the question I'm sure you all can help with: can someone show me some simple breathing solutions for a scenario like this?

I can't give my protagonist full scuba equipment. But is there maybe some kind of small tank with a regulator?

 

[hunterjwizzard]

These are also in current use for mine emergencies so having your character obtain one wouldn't be too implausible. For example: M-20.3 Emergency Escape Breathing Device | Products | Ocenco

This works best, think I'll go with that. Its the sort of thing my character would likely obtain.

Got any firearms questions? That's my real area of expertise

Not until the next book in the series, but I'll come back if I think of anything

 

[lowwall]

Awesome! Thanks for the explanation!

Now for the question I'm sure you all can help with: can someone show me some simple breathing solutions for a scenario like this?

I can't give my protagonist full scuba equipment. But is there maybe some kind of small tank with a regulator?

Already answered. But if you want him to be wearing it, the best answer would be either one of the rebreathers I mentioned above or a fire fighters SCBA unit.

Self-contained breathing apparatus - Wikipedia

en.m.wikipedia.org

 

[boulderjohn]

but things like that stretch my willing suspension of disbelief past the breaking point.

I thought the non-English teachers in the thread would like an explanation of this.

A couple hundred years ago, Samuel Taylor Coleridge said that when experiencing fiction (books, plays, movies), we have a "willing suspension of disbelief" that enables us to experience the story as if it were real. It's what makes us scream in terror at a horror movie, even though we know it isn't real. That effect is lost, however, when the author does something that goes too far and reminds us that we are experiencing mere fiction. The spell is broken.

Here is an explanation I used with students. When I watch The Wizard of Oz, I suspend disbelief in that fantasy world. I become friends with a talking scarecrow, an overly emotional tin man, and a cowardly lion. I am frightened by the flying monkeys. But when Dorothy says she wants to go back to Kansas, I am sorry, but that is too much of a strain on credibility. It's over.

 

[RobPNW]

It’s a novel not a science paper.

I actually applaud the effort to make things as realistic as possible. I don’t know how many movies that I start and don’t finish because the writers either have no idea what they’re talking about or don’t care enough to research. I know it’s just entertainment but my brain can’t ignore something that it knows is stupid