Nitrogen Bag CTB - Bottle Capacity

[Shaqxbb]

Hi there,

As some of you may have seen in other posts of mine I am considering the nitrogen bag to CTB. My other option is a firearm as that's basically foolproof, but the bag leaves much less (read: no mess) for anyone to clean up. That said, I'm worried about the capacity of the Max Dog canisters. The mega thread on exit bags indicates that 15 minutes of flow (when used properly) is enough to CTB. The Max Dog bottles should provide for about 20 minutes of flow. Let's say 18 minutes providing for a few seconds here and there of test, plus some margin of error.
So: 15 minutes to physiologically CTB. 18 minutes of flow when configured properly. Does anyone know where the 15 minute number comes from? I'm a 28 year old, physically healthy and in-shape male 180lbs 5'11". I am trying to verify that one bottle will surely be enough to get the job done. If not, I have faith in my own ability to construct a manifold to run two bottles simultaneously at 16LPM (regulated at 2x8LPM) thus doubling the runtime of the nitrogen by doubling the reservoir capacity.
That said—anyone have ideas as to how long the body actually takes to die in this situation?

 

[frees]

20 minutes of gas is enough, albeit on the short end. When using high pressure cylinders like with the Maxx Dog reglulator you have the option to simply use larger cylinders. As i would suggest for peace of mind and to leave room for errors.
If you decide to buy two sets of Maxx Dog cylinders you can use a simple T-piece for your tubing or run both tubes into the bag separately. However, gas cylinders are easy to get.

 

[Absurdity]

There are two values that are important: time to death and flowrate of the gas. From these two you can then calculate the required cylinder size.

Flowrate: 15 l/min -- from the PPeH (they did an experiment and this value was deemed more than enough to prevent CO2 alarm response)
Time to death: on average ~13 min, range 2-40 min -- don't know the original source, but here is more about these numbers (original probably some medical paper?); though the PPeH recommends 20 min

With 15l/min and 20min we get a required volume of 300l, equal to a 1.5l gas cylinder at 200bar. The smallest nitrogen tanks I found were 2l, so in theory more than enough.
But I agree with @frees and will probably just get a larger cylinder to feel safer and thus be more relaxed (I think that will help to overcome the survival instinct). That way I can also use the smaller cylinder I have right now to do some testing.

Though I wonder if the attempt would really fail if the gas runs out too soon. You will still have the bag on your head, tightened around your neck. And if you're still breathing at that point your breaths will probably just deflate/inflate the plastic bag, without drawing much new air into it?

 

[frees]

If one manages to do it somewhat right (breathing air with very little oxygen left) time to brain death is under 15 minutes. Breathing stops earlier, so gas flow is not important at that time if a somewhat oxygen-free atmosphere is maintained (exit bag stays inflated). That 40 minutes max value comes from one case in the early trials in switzerland where they used medical oxygen masks.

With 15l/min and 20min we get a required volume of 300l, equal to a 1.5l gas cylinder at 200bar. The smallest nitrogen tanks I found were 2l, so in theory more than enough.
But I agree with @frees and will probably just get a larger cylinder to feel safer and thus be more relaxed (I think that will help to overcome the survival instinct). That way I can also use the smaller cylinder I have right now to do some testing.

Yeah, for various reasons i recommend 5 liter @ 200 bar cylinders. They are only marginally more expensive than 2 liter bottles and their size and weight is still easy to handle.