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mfb- t1_j876vxs wrote

If the tube is open: Sure. There is nothing that would stop it.

Edit: This thread transitioned from a purely hypothetical question to a safety question.

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dogeheroic t1_j878df7 wrote

Replying to SnekkyGlekky (#1,785,438)

Depends on the pressure and temperature differential. You could have a face of the mountain be in direct sun heating up wand creating a difference in pressure. It's not about how windy it is, the pressure delta is what makes wind

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mermaldad t1_j878pmf wrote

Replying to SnekkyGlekky (#1,785,438)

No, the length of the tube might slow the wind down, but it should still move air through the tube. I assume you are thinking of crawling through the tube. I would certainly take precautions before attempting such a thing. Perhaps search for spelunking resources that can tell you what equipment to take, what procedures to follow, etc.

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PerspectivePure2169 t1_j87eab4 wrote

This does not sound hypothetical to me. There's several ways you can die doing this:

If this tube is iron and was sealed airtight, the rust that has occurred inside will consume the oxygen within. People have died entering pontoons, tanks, pipes etc for this reason.

If there's decaying material oxygen can be reduced in a similar way, and hydrogen sulfide can also be present, which can incapacitate you even if there's enough oxygen.

It might be okay, it might not. Mostly low oxygen conditions won't give you a warning, you will just pass out.

You should stay out of it. If you can't resist, then rent a gas sniffer to check O2, CO2 and hydrogen sulfide levels.

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oOFrostByteOo t1_j87mkwt wrote

No confined space should ever be assumed safe without instruments to check air quality. Many a people have died from entering vaults, tunnels, caves etc that had unforseen reasons for the oxygen to be displaced/consumed. And usually you won't even realize your dying.

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Maxtrt t1_j87mozc wrote

Boyle's law, The air will automatically expand into the pipe because gasses always expand from a higher concentration to a lower one. Since the tube is open on at least one end it will always have air circulating through it and since it's open on both ends it will constantly be refreshed so there is no chance of using up all the air in the confined space.

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Captain_Poodr t1_j87om89 wrote

While there is air inside, it might not be the kind you want to breathe. Depends on what the pipe is made of and used for. I don’t think you would be in trouble if the run wasn’t so long, conditions would have to be almost ideal. Wear a gas mask if you’re going to mad-lad it OP. 400m is a long way to go prone.

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Swissaliciouse t1_j87vncy wrote

Technically & hypothetically, yes. There is no reason why you can not have substantial airflow through this conduct. especially through a hill you easily can have wind or heat differences that creates a pressure difference leading to airflow.

From a risk analysis point of view: No it will not always be safe. See many of the other answers.

In reality you use blowers to make sure that the air insides such a tube is indeed ambient air.

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colcob t1_j87vtch wrote

In a hypothetical situation in which the tube is inert, clean, empty and open and one or both ends, then yes it will be full of air of the same constitution as the surrounding air.

In a real life situation where it could be full of rotting stuff, degraded materials etc. then at 400m long and 0.6m diameter it’s very possible that air contaminants in the middle could be build up enough to be hazardous.

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vettrock t1_j87xteq wrote

A tube that is open is going to be filled with air. How much of that air is exchanged, and how long you are in the tube are factors. If there is wind/fans you are probably fine. Also how long are you sitting in the middle? If stagnant, and there is other rotting material, it becomes much more problematic.

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Efficient-Damage-449 t1_j88e01u wrote

Multiple posts have detailed how this can go off the rails and be a bad idea. Yes, it is a bad idea. But if the tube is open there is probably a pressure and temperature differential on both sides so there will most likely be a nice breeze keeping the air fresh. At least there will be a breeze until there isn't one.

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duhvorced t1_j88h2il wrote

Replying to SnekkyGlekky (#1,785,408)

Since this is clearly not a hypothetical based on your other comments…

  • what is the nominal purpose of the tube? Drain pipe? Irrigation?
  • Is the tube open at both ends?
  • Is there any sort of airflow through it? (Take a handful of dirt/dust, let it fall directly in front of the tube opening, watch dust carefully for signs of air movement.)

If the tube is open, at that length I would expect the natural conditions (temperature and pressure differentials) to create a natural airflow, in which case it’s almost certainly breathable.

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