To use argon bottle or not?

[LiteHedded]

helium is cold. for reals.
use the airgon

 

[_Ralph]

Well that escalated quickly (what doesn't on SB)....

Since Stuart asked about warmer water diving and helium, that was my response (deco bottle).

Now for the long answer ...


Caribbean dry suit diving, not bothering with flying down an AL6... I'll put a hose my my 50% bottle (most places don't see dry suits down there, let alone have AL6's).

I open it a crack (just like an AL6) when I need some suit gas, closed afterwards.

Wouldn't do it with a 100% bottle as then I'm probably diving 32% (or have a 50% bottle).

IN WARM WATER, I have no electrical (or chemical .... Dependent on breakfast) inside the suit.

If I'm in cold water, an AL6 or larger would be best...... And would be areanged upon arrival, or brought along.


_R

 

[Andrew Donn]

Use the dry suit inflation bottle for sure. Whether it is filled with air or argon won't make much difference for the dive being contemplated. I've made the mistake for similar reasons more than one and regretted it every time. Simple rule - if the bottom mix has any helium in it always use a separate inflation bottle. 2nd best option is to plumb into your deep deco bottle.

 

[kensuf]

Use the dry suit inflation bottle for sure. Whether it is filled with air or argon won't make much difference for the dive being contemplated. I've made the mistake for similar reasons more than one and regretted it every time. Simple rule - if the bottom mix has any helium in it always use a separate inflation bottle. 2nd best option is to plumb into your deep deco bottle.

You mean "deepest nitrox bottle"? Some of my deco bottles have 25-45% helium in them.

 

[Jared0425]

What water temps, though?

I'll be in water so warm, I'm not sure the extra thermal conductivity of the helium will matter.

I usually wear a 3/2 wetsuit down to around 70f. For this dive, it'll be 75-ish, and I'll be dry.

I dive in cold fresh water where it's in the high 30's.

@ralph
And avoid using a stage bottle for your drysuit. It adds more complications if you have to change, share, or give your bottle up.

 

[KevinNM]

On second thought, one or two things do come to mind that could make this possible.

[begin theory spinning]

In order to have a fire you need to have oxygen, a heat source hot enough to ignite a fuel and a fuel. Cases of spontaneous combustion can be been achieved with some metals like titanium under the right conditions but that's outside the scope of a discussion about an undergarment catching fire.

So right away when you're putting a high nitrox mix in your suit you have oxygen and a fuel source, which is the undergarment itself. All that is missing is a heat source hot enough to start a fire.

Two things come to mind that could potentially give the heat.

One is a malfunctioning electrically operated thermal vest. It's attached to a battery and it's full of wires so potentially I could see it sparking a fire if some kind of a short circuit were to happen.

The other is if the diver unwittingly used the kinds of hand warmers in the vest that react with oxygen. Under pressure they get much hotter as the partial pressure of oxygen goes up and if you were to put in a high nitrox mix on top of that then the heat would go WAY up.... maybe hot enough to start a fire. I know there have been cases of divers being burned by not understanding how hand warmers work in the past so this idea seems somewhat plausible to me if the temperature could go high enough.

[/end theory spinning]

I guess this could be an argument for putting argon in the vest, particularly if the diver were using a battery powered thermal vest. The hand warmer thing is more of a "Darwin" issue that would hopefully only end in something they would have to explain to their spouse.

R..

Oil products will also ignite spontaneously in 100%.

Link is an ugly picture as to what can happen.
http://www.pdo.co.om/hseforcontractors/LibraryDocuments/20080618072911.pdf

 

[KevinNM]

Not enough heat. 100% sure of that. A discharge of static electricity contains far too little energy to generate the heat required to ignite an undergarment. What happens in a static discharge is that a flow of electrons happens from A to B, usually using the human body as a sort of "ground" or "capacitor", therefore causing an electrostatic discharge with a measurable voltage that can be quite high but with a current of almost zero. The discharge also takes place very fast so the amount of energy generated is normally expressed in milijoules. The reason you feel it so well is that our nervous systems also work on these levels of energy, so it can feel worse than it really is. However, in terms of "heat", static electricity creates very little heat.

To put this another way, you can see voltage as how fast the electrons are moving and current as how many electrons are moving.

To use an an analogy, think of a garden hose. Voltage is how fast the water comes out of the hose and current is the volume of water that comes out of the hose. If both are high then the stream of water is powerful, maybe even powerful enough to cut metal. If the water comes out very fast but it's only a tiny little stream a few molecules wide then you might have to concentrate to even feel it.

That second thing is static electricity.

So in order to boil a liter of water with static electricity, or to start an undergarment on fire, you would need a sustained static discharge of a HUGE amount of time (I'm going to spare you the math here but let's just call it a HUGE amount of time, on the order of ten quintillion (that's 10 followed by 18 zeros) times longer than normal to create enough heat for our scenario.

R..

You can cite all the theory you want but people have in fact died from static discharges starting fires in 100%. Do not underestimate how dangerous 100% is.

Hyperbaric Chamber Deaths: Dr. George Daviglus and Lance Bark charged with two deaths

 

[Diver0001]

You can cite all the theory you want but people have in fact died from static discharges starting fires in 100%. Do not underestimate how dangerous 100% is.

Hyperbaric Chamber Deaths: Dr. George Daviglus and Lance Bark charged with two deaths

As I said above there needs to be heat, fuel and oxygen to cause a fire.

I also mentioned that certain metals will spontaneously combust in under certain conditions. The post I made, however, was about what it would take to light an undergarment on fire during a dive.

In your first post above you referenced the dangers of oil (fuel) and oxygen. Under some conditions -- in the presence of certain metals -- oil can be a catalyst for spontaneous combustion but such conditions will not be present in the under garment of a drysuit.

In the second post, the writer of the article clearly has no idea what they are talking about because they talk about the "oxygen igniting". Oxygen cannot ignite. The fuel ignites. This leads me to believe that we cannot draw any conclusions about what actually happened in that case by reading that article. The "spark" they referenced in the article is highly unlikely to have been a static discharge. As I said above, there just isn't enough heat there to cause a fire even if it's intuitively clear that pure O2 is dangerous stuff.

R..

 

[Lorenzoid]

. . .
In the second post, the writer of the article clearly has no idea what they are talking about because they talk about the "oxygen igniting". . . .

I know little about the subject, but it's very interesting. The article does make that statement, but then it continues with this:

They were not wearing the recommended 100 percent cotton garments, or "scrubs," that are supposed to be provided. Pesce had two metal belt loops on her pants and underwear that was 35 percent synthetic. Under his polyester shorts, Francesco wore a disposable diaper containing polymers, plastics and ink, all flammable.

They had baby wipes containing alcohol and other chemicals not permitted inside the chamber.

 

[KevinNM]

As I said above there needs to be heat, fuel and oxygen to cause a fire.

I also mentioned that certain metals will spontaneously combust in under certain conditions. The post I made, however, was about what it would take to light an undergarment on fire during a dive.

In your first post above you referenced the dangers of oil (fuel) and oxygen. Under some conditions -- in the presence of certain metals -- oil can be a catalyst for spontaneous combustion but such conditions will not be present in the under garment of a drysuit.

In the second post, the writer of the article clearly has no idea what they are talking about because they talk about the "oxygen igniting". Oxygen cannot ignite. The fuel ignites. This leads me to believe that we cannot draw any conclusions about what actually happened in that case by reading that article. The "spark" they referenced in the article is highly unlikely to have been a static discharge. As I said above, there just isn't enough heat there to cause a fire even if it's intuitively clear that pure O2 is dangerous stuff.

R..

NFPA Journal - The Air in There, Jan Feb 2017
"The grandmother apparently adjusted a cushion, and a buildup of static electricity generated a spark—enough to trigger a violent fire in the oxygen-enriched environment. She banged on the chamber to get someone’s attention, but when an attendant did appear, the chamber had to be depressurized for 90 seconds before it could be opened."

What lubrication do you use on your dry suit valves? My SI Tech ones use silicone grease.

Also see
THE RISK OF STATIC SPARK IGNITION IN ENRICHED OXYGEN ENVIRONMENTS
[abstract] THE RISK OF STATIC SPARK IGNITION IN ENRICHED OXYGEN ENVIRONMENTS