Is exit bag painless?

[thehorizons]

If they died, it was effective for them. This position could be less efficient in case of using helium, since its low density can imply better displacement of air downwards than in other directions. This doesn't apply to nitrogen and argon (although nitrogen is slightly less dense than normal or exhaled air as long as their temperatures are equal, the difference in the real temperatures under the conditions implied by the given method can easily make relatively cold nitrogen coming from the cylinder slightly more dense than exhaled air and air entered the bag from outside).

Difficult to say without having the full picture.

The argumentation in the megathread assumes a higher risk of displacing the bag in this position. It sounds reasonable.

What was the point of you showing pictures of the heluium deaths then? We're talking about Nitrogen. If you're even acknowledging about the general consensus about the bag being displaced when lying down, why correct me and imply that lying down doesn't matter with Nitrogen and in general lying down is ineffective with Nitrogen?

 

[Intoxicated]

What was the point of you showing pictures of the heluium deaths then? We're talking about Nitrogen.

The general method is inert gas asphyxiation, and among helium and nitrogen only the former could potentially displace air better in the sitting position.

If you're even acknowledging about the general consensus about the bag being displaced when lying down

Actually the odds of such displacement can be minimized by putting a bit more effort in securing the bag.

why correct me and imply that lying down doesn't matter with Nitrogen and in general lying down is ineffective with Nitrogen?

I don't see any evidences confirming that lying down necessarily renders the method ineffective; it can only be presumed that sitting can sometimes be better than lying down.

 

[DeathSweetDeath]

The general method is inert gas asphyxiation, and among helium and nitrogen only the former could potentially displace air better in the sitting position.


Actually the odds of such displacement can be minimized by putting a bit more effort in securing the bag.


I don't see any evidences confirming that lying down necessarily renders the method ineffective; it can only be presumed that sitting can sometimes be better than lying down.

I've seen the pics of those who have CTB'd with it laying down, but The PPH says never to do that with inert gas (not just helium). I always thought it was because in a chair, gravity would be working with the exhaled CO2 so it would go down & out of the bag, and making it less likely that air would get into it.

 

[Intoxicated]

I've seen the pics of those who have CTB'd with it laying down, but The PPH says never to do that with inert gas (not just helium).

Which edition(s) of PPH do mention body position? I couldn't find any related considerations in the editions I have.

I always thought it was because in a chair, gravity would be working with the exhaled CO2 so it would go down & out of the bag, and making it less likely that air would get into it.

That could make sense if we exhaled pure or somewhat concentrated CO₂. However, in the air we exhale it's blended with other lighter gases, including very light water vapours, so the actual density of the mix is much less than that of pure or concentrated CO₂. A possible composition of exhaled gases can be

75% N₂ + 15% O₂ + 5% H₂O + 4% CO₂ + 1% Ar

See Composition of Air.

In such a mixture, the average molar mass is

(75% * 28.0 g/mol + 15% * 32.0 g/mol + 5% * 18.0 g/mol + 4% * 44.0 g/mol + 1% * 40.0 g/mol) / 100% ≈ 28.9 g/mol

Blending of gases due to thermal molecular movement and currents prevents stratification of gases by their molar mass within small ranges of altitude.

Why don't the gases in the atmosphere separate out according to mass?

The temperature of exhaled air commonly varies between 31 °C and 35 °C - see

Measurement of temperature and relative humidity in exhaled breath | 10.1016/j.snb.2019.127371_Science Hub

tesble.com

The density of ideal gas is

ρ = M * p / (R * T)

where M is the molar mass, p is the pressure the gas, R is the universal gas constant, T is the absolute temperature of the gas.

If ρ₁ is the density of nitrogen at 20.0 °C and ρ₂ is the density of the exhaled gas composition mentioned above at 33.0 °C and the same pressure, then ρ₁ / ρ₂ can be roughly estimated as

( 28.0 g/mol * p / (R * (273.15 + 20.0) °K) ) / ( 28.9 g/mol * p / (R * (273.15 + 33.0) °K) ) = (28.0 g/mol / 293.15 °K) / (28.9 g/mol / 306.15 °K) ≈ 1.01

which means ρ₁ > ρ₂ (colder dry nitrogen is slightly denser than warmer moist exhaled air).

When we replace oxygen and argon with nitrogen in our lungs, the composition of the exhaled air could change to something like this

81% N₂ + 8% O₂ + 5% H₂O + 4% CO₂ having the average molar mass of ~ 28.0 g / mol - same as for nitrogen.