Method Exit bag and inert gas megathread

[scientificmethid]

I've seen the standard 25 L/min nitrogen flow rate mentioned in multiple sources (like PPEH), but I suspect that number has more to do with regulator limitations than optimal gas flow. Many click-style regulators top out at 25 L/min, which may have set the standard by default.

My current setup provides 40 L/min total:

• Tank A: 25 L/min into the EEBD hood's main inlet (which includes a built-in exhalation valve)
• Tank B: 15 L/min through a second line routed like in a standard exit bag configuration into the EEBD hood.

This configuration seems solid, but I'm open to upgrading the second regulator if there's a meaningful benefit to reaching 50 L/min total. I'm not trying to scrape by on "good enough." I want certainty, and I want to ensure the least suffering possible—rapid oxygen displacement, continuous CO₂ flushing, and no physiological surprises.

For reference, EEBDs used in fire escapes recommend 36-40 L/min just to support high ventilation and toxic gas clearance. Since nitrogen is inert, and since there's no oxygen support involved, it seems reasonable to meet or exceed that benchmark.

One side note: I'm not at all concerned about sound or airflow. I sleep with a fan pointed at my face every night—so if anything, the sensation of gas moving near my face will feel familiar, maybe even comforting.

If anyone with technical experience or first-hand insight sees an issue—or has thoughts on whether going from 40 L/min to 50 L/min meaningfully improves outcomes—I'd really appreciate your input.

40/L per minute seems like a lot. That's a lot of air moving and I think you'll have major leaks around your mask seal from sheer volume of air movement at 40/LPM+

 

[OutOfTime]

male CGA580 to female G5/8" adapter

Thank you very much.

I've looked for this and all I can find are male to male adapters like in this picture. Is there anywhere anyone knows that sell "male CGA580 to female G5/8" adapter"

 

[bored2death]

Thank you very much.

I've looked for this and all I can find are male to male adapters like in this picture. Is there anywhere anyone knows that sell "male CGA580 to female G5/8" adapter"

they exist on european websites and some online auction sites. i dont want to violate TOS by saying more

 

[th3_t1r3d_0n3]

Hi. Would a 9kg LPG cylinder be enough gas for using an exit bag? There isn't much info on using LPG, does the PPH cover this?

 

[plytiene]

Hi. Would a 9kg LPG cylinder be enough gas for using an exit bag? There isn't much info on using LPG, does the PPH cover this?

I don't think LPG is an inert gas, so it does not lead to a peaceful death by the PPH standards and isn't discussed by them. Inert gases are Helium, Nitrogen, Argon. The latter two are the recommended ones due to being available via welding supplies, while Helium became more regulated with exit bags becoming more in vogue.

 

[th3_t1r3d_0n3]

I don't think LPG is an inert gas, so it does not lead to a peaceful death by the PPH standards and isn't discussed by them. Inert gases are Helium, Nitrogen, Argon. The latter two are the recommended ones due to being available via welding supplies, while Helium became more regulated with exit bags becoming more in vogue.

It should be though because in South Africa there are are couple of cases where entire families die from household LPG leaks.

 

[OutOfTime]

they exist on european websites and some online auction sites. i dont want to violate TOS by saying more

Would you be open to DMing me the websites? I believe it is acceptable if it is in private messages. I would really appreciate it as I am desperate to have my setup.

 

[kreikrei]

Sent you a PM

So the Hood quick connect plug is 1/4" according to Zardofan's post.
From what I can tell in the hood photo...that fitting is a Hi-Flo V style...which they call 'H' below.


View attachment 161954

There are also universal female couplers that all the plug styles can fit into.

View attachment 161956

Hi, can you please send the search term for ebay as well?
I already have a 99.99% 1500 liter argon cylinder and a suitable pressure regulator, just need the connections and to finally choose the most suitable mask TYPE :)
Thank you!

 

[plytiene]

Did youtube purge exit bag construction guides? The OP strongly recommend watching them but youtube itself wards off searching and search engines don't seem to find them onto it either.

E: Oh, that's the video in the resource thread compilation. I'm an idiot.

Spoiler

 

[77redbike]

My experience was that I soon began to feel tingling in my hands, as if they were falling asleep. A short moment later I began to get dizzy, and my vision went grey around the edges. Each of the three times I have attempted this method, that's as far as I got before I flinched and removed the bag.

I did not experience any pain whatsoever, and no real discomfort aside from the mild tingling in my hands.

I do not believe I have suffered any ill effects from three aborted attempts. I had a bit of a cough for a couple days after my third attempt, but I can't say for sure whether that was attributable to the N2. It concerns me only in that this method demands that you be able to breathe freely in order for it to be effective, and I don't want to have ruined my chances to use it later, when I have summoned my courage.

My greatest difficulty is that I have been very stressed during my attempts, and could not keep my breathing steady and deep. This undoubtedly lengthened the amount of time it should have taken for me to black out.

In the stress of the situation, I experienced time dilation —in other words, I can't tell you how long it took for me to feel dizzy; it might have been five seconds, it might have been a minute and a half. It wasn't very long —but it was long enough for me to flinch.

From my experience, this is as painless, comfortable, and potentially peaceful a way to ctb as it is rumored to be. The only drawbacks that I can see are that it requires a lot of equipment —cylinder, regulator, hose, bag— and that there is a surprising amount of time for your survival instinct to kick in, or for second thoughts.

As I wrote at the beginning, I hope other forum members can fill in some of the blanks I have left —specifically, I have seen a lot of questions about tank sizes outside the US that I cannot answer.

I don't wish anyone good luck at catching the bus. I wish we could all find our way to a joyous and satisfying life that would make death an unfortunate reality rather than a longed-for relief. But all of us here know that the Fates aren't always that kind, and so I wish you all the most peaceful relief from your pain that you can find, and if that peace is brought by Death, I hope Death comes gently.

Any compressed gas cylinder --flammable or non-flammable gas-- is a potential missile waiting to go off. Just damage that valve and you'll find out what pressurized inert gas can do. Will you get a fireball? No, of course not, but compressed gas cylinders can be very dangerous if they're not handled with due caution. The point of that part of my post is that the people selling you those cylinders need to know you're aware of the hazard. Flub that detail and you might be denied your N2.

Perfect! Thank you for adding this. I might consider that for myself.

Yes. Emphatically yes.

My intent for this post was to cover the basics and hopefully answer some of the questions I have read many times. It is not meant to be --and cannot be-- an encyclopaedic gathering of all information on the subject. Hopefully people will continue to add to it, post links to useful resources, etc.

3/8" elastic drawstring cord seems large, are you sure that's what you have?

 

[oono]

Regarding the Ocean Reef Neptune 3 mask for the SCUBA method, I'm wondering which port the first stage regulator should be connected to? Please.

 

[77redbike]

The Regulator:

A regulator screws on to the cylinder and does two things: 1) it reduces the pressure in the cylinder to a useable level, otherwise the 2000psi tank pressure would just blow the exit bag off your head as soon as you opened the valve, and 2) it controls the rate of gas flow into the exit bag —specifically, it should release it at 15Lpm, which is the minimum adequate to carry away exhaled CO2 and fool your lungs into believing there's enough air.

The good news is that while gas cylinder sizes are not globally standardized, the cylinder valve threads are —and both N2 and Ar cylinders have the same threads (other gasses have different threads), so a regulator that fits on one cylinder will fit equally well on another.

You don't need to worry about being sure to choose a regulator that will reduce the pressure: they all do that. The flowmeter is the critical element of the regulator for our purposes.

Some regulators come with a "click adjust" flowmeter that is very simple, allowing you to dial in 15Lpm without needing to think about it. To the best of my knowledge, these are medical grade regulators; generally very good quality, but often a bit more expensive. Others here may know more about them, and where to acquire them, than I do.

A typical welding regulator will have two gauges: the tank pressure gauge (unimportant to us) and the flowmeter gauge.

A welding regulator's flowmeter gauge will be marked in either cubic feet per hour (Cfh), Lpm, or both. Some welding systems require a fairly low flow of inert gas, much lower than our necessary 15Lpm, and this low flow is most easily measured in Cfh. If you see a gauge marked only in Cfh, it probably will not work for our purpose. Look at the highest Cfh setting on the flowmeter and do the math, to be certain. If the gauge reads in Lpm, a glance should tell you whether the regulator provides the necessary 15Lpm flow.

Harbor Freight Tools offers a cheap CO2/Ar regulator (it also works for N2) with a flowmeter that shows flow in both Cfh and Lpm and goes high enough for our purposes. This is what I have.

The Hose:

The hose needs to be long enough to reach from the gas cylinder beside you, up into the exit bag on your head. I have found it easiest to lead the hose up my back and into the bag at the very back of my neck. It seems to disrupt the fit of the bag less right there.

Some regulators come with a hose that threads directly into the regulator body. Some regulators come with a hose-barb, onto which a length of soft tubing can be pressed. Some regulators come with neither.

For the first situation, just thread the hose into the regulator, tighten it with a wrench, and it's ready.

(Regardless of what type of threaded fitting is used, you do need to wrench-tighten this fitting: a lot of gas can leak out at this connection. If it is a brass fitting, you should not need teflon tape on the threads; the soft metal deforms enough when tightened to provide an adequately gas-tight connection.)

For the second situation, take the hose-barb to a hardware / home improvement store and purchase tubing that fits onto the barb. Once home from the hardware store, thread the barb into the regulator body, tighten with a wrench, and press the tube onto the barb. It should be a snug fit; if you're worried it's too loose, use a small hose clamp / jubilee clip to secure it in place. If it's a little too tight to get the hose into place, soak the end of the tube in very hot water to soften it and press it onto the barb. I used clear vinyl tubing. Aquarium tubing should work. Surgical tubing may not; I don't know for sure.

For the third situation, you'll need a hose-barb fitting (typically brass) that threads into the regulator body. Take the entire regulator to the hardware store and ask someone to help you fit it with a hose barb. Then proceed as for the second situation.

Cover story: as with purchasing the gas cylinder, you're using N2 for brewing, or Ar for filling partial paint cans. Why Ar? because it's heavier than air and settles down onto the paint surface inside the can. For extra confidence that they won't ask inconvenient questions, you're doing it for your father, or your brother, and you don't know why they want it for their paint locker, they just said to get a hose barb and six feet of tubing…

The Exit Bag:

There are several videos on YouTube detailing construction of exit bags. I strongly recommend watching them. That's how I learned.

The short version of what you want is a turkey roasting bag —available in the supermarket, in with the zip-locks and cling wrap— with an elastic drawcord worked into a turned hem, and a cord-lock to adjust the drawcord's tension.

I used 3/8" elastic cord. I purchased both it and the cord lock at a sewing and crafts store (JoAnn's).

To construct the turned hem you'll need micropore (surgical) tape, available at a pharmacy in the first aid section. It's the right tape to use because it will reliably stick to the material of the bag itself. Sometimes it isn't labeled as "micropore." Ask a clerk if you can't find it.

Cover story: you were asked to re-stock the family first aid kit with micropore tape and you don't recognize any of the brands available.

Using an elastic drawcord is important: it needs to fit snugly around your neck, but not seal tightly. It must still be flexible enough for the flow of inert gas, lightly pressurizing the exit bag, to push past the elastic and flush away the CO2 you're exhaling. Don't use a non-elastic drawcord or do something like duct tape the bag to your neck; you don't want to create a seal, just a restriction.

3/8 " cord sounds big, are you sure that's what you have?