Heliox!

[DeepSeaDan]

...thermal considerations...

...almost all of my commercial heliox diving utilized hot water suits for thermal protection; those few unfortunate times I did extended surface gas dives in cold water in just a dry bag was a major shiver! Mind you, the argon suit filler is a bonus, but I doubt it could overcome the significant respiratory heat loss issues of heliox.

...During my later years of L. Erie gas diving, I recall that Dr. Hamilton approached the diving operators with the idea of utilizing trimix; however, because we had been diving deep air for so many years without incident, the idea was mostly ignored - a pity, in my opinion.

Regards,
D.S.D.

 

[MikeFerrara]

...thermal considerations...

...almost all of my commercial heliox diving utilized hot water suits for thermal protection; those few unfortunate times I did extended surface gas dives in cold water in just a dry bag was a major shiver! Mind you, the argon suit filler is a bonus, but I doubt it could overcome the significant respiratory heat loss issues of heliox.

...During my later years of L. Erie gas diving, I recall that Dr. Hamilton approached the diving operators with the idea of utilizing trimix; however, because we had been diving deep air for so many years without incident, the idea was mostly ignored - a pity, in my opinion.

Regards,
D.S.D.

Breathing helium doesn't make you colder, although, using it in your dry suit will.

One reason not to use heliox is that most of us can't get a tank full without a booster. I mix trimix by transfilling helium, some O2 and then topping with air. With a continuous flow system you can use it to make trimix directly or transfill helium and then top with nitrox. Either way there's no getting around having some nitrogen in there.

When I say we can't get a tank full without the air/nitrox top from a compressor it's because the hightest pressure tanks we can get from the gas supplier are 2600 psi and sometimes we have trouble getting them much over 2000 psi. So...to partial pressure blend heliox and get your tank full you'll need a booster.

But, some divers and shops have boosters and these days more than a few divers are using heliox for decompression such as 50% O2 and 50% helium for a 70 ft gas switch in place of EAN50.

At very deep depths some nitrogen helps minimize HPNS also but most of us don't go deep enough to worry about that.

 

[MikeFerrara]

Here's a link to a good thread for those who are interested. http://www.scubaboard.com/showthread.php?t=41303

 

[DeepSeaDan]

Breathing helium doesn't make you colder, although, using it in your dry suit will.

One reason not to use heliox is that most of us can't get a tank full without a booster. I mix trimix by transfilling helium, some O2 and then topping with air. With a continuous flow system you can use it to make trimix directly or transfill helium and then top with nitrox. Either way there's no getting around having some nitrogen in there.

When I say we can't get a tank full without the air/nitrox top from a compressor it's because the hightest pressure tanks we can get from the gas supplier are 2600 psi and sometimes we have trouble getting them much over 2000 psi. So...to partial pressure blend heliox and get your tank full you'll need a booster.

But, some divers and shops have boosters and these days more than a few divers are using heliox for decompression such as 50% O2 and 50% helium for a 70 ft gas switch in place of EAN50.

At very deep depths some nitrogen helps minimize HPNS also but most of us don't go deep enough to worry about that.

...I must differ with you on this one; here's a quote from N.O.A.A. on the subject, after a quick googling...


" One type of mixed gas diving involves the use of heliox. This (helium 79% and oxygen 21%) mixture is often used for very deep diving. Unlike nitrogen, helium is not known to have an intoxicating effect at any depth; it has a lower density than nitrogen, making it easier to breathe; and in cases of extended submersion, it improves decompression. Still, heliox has its drawbacks. It is expensive, has a limited availability, and its thermal conductivity is six times greater than that of nitrogen. This means that a diver breathing heliox will lose body heat six times faster than someone breathing compressed air or nitrox, making them susceptible to hypothermia. To prevent this, divers often wear special suits filled with hot water that is pumped down from the surface. Heating the heliox before the diver inhales it is another strategy used to combat hypothermia. Either of these procedures require specialized equipment and highly trained personnel."

...I can get you more, if you like.

Best,
Dano

 

[padiscubapro]

...I must differ with you on this one; here's a quote from N.O.A.A. on the subject, after a quick googling...


" One type of mixed gas diving involves the use of heliox. This (helium 79% and oxygen 21%) mixture is often used for very deep diving. Unlike nitrogen, helium is not known to have an intoxicating effect at any depth; it has a lower density than nitrogen, making it easier to breathe; and in cases of extended submersion, it improves decompression. Still, heliox has its drawbacks. It is expensive, has a limited availability, and its thermal conductivity is six times greater than that of nitrogen. This means that a diver breathing heliox will lose body heat six times faster than someone breathing compressed air or nitrox, making them susceptible to hypothermia. To prevent this, divers often wear special suits filled with hot water that is pumped down from the surface. Heating the heliox before the diver inhales it is another strategy used to combat hypothermia. Either of these procedures require specialized equipment and highly trained personnel."

...I can get you more, if you like.

Best,
Dano

someone doesn't know their physics, or that the author's assumption is that the thermal protection used by the diver (eg drysuit) is using the same gas for suit inflation...
search the board, there are some very detailed explanations about thermal conductivity, specific heat ect...

Helium heats up much more rapidly (takes heat away by contact much faster) but its thermal capacity is less than that of n2, so it takes less energy to raise the gas to the same temperature.. In the lungs everyting we breathed is brought up to near body temperature.. He will pull the heat away and get it there faster, N2 will get it to the same temperature but take about twice the energy..

If your body is surrpunded by Heliox its a totally different issue.. You will transfer heat back and forth (body to heliox to water ) much faster..

 

[PaulSmithTek]

I agree! Being commercially cerified for mixed gas diving. Heliox is a lighter gas and will make you colder. Dove it with out using it in the dry suite and you are much colder.

 

[D1V3R]

I here alot of contradictions with heliox and trimix
in my own experience it seems that when you breathe helium it is warmer than air, but when you fill your drysuit with it (for the love of god do not try this) it is very cold.

I did research on this topic, and I found in the "Wakulla Springs project" that helium warms as fast as it cools down, so if your breathing it, it is warmed by your body. but when it goes into a habitat or drysuit it is cooled quickly by the water.
Its all about its usage

 

[BigJetDriver]

Heliox is easy to fill in the small tins used in eCCR's, is not that expensive in such small amounts, and works well with RGBM in the H-S Explorer.

 

[padiscubapro]

I agree! Being commercially cerified for mixed gas diving. Heliox is a lighter gas and will make you colder. Dove it with out using it in the dry suite and you are much colder.

I am assuming you were using a helmet (or some type of gear that extends the surface area like a FFM) with surface supplied gas (but scuba will also do the same) am I correct?? This is a very different condition than an oc reg connected to a tank..

If this is the case you head (or face) is surrounded by a gas that will pull heat very quickly away from the part of your body that gives up heat the fastest (thats in contact with a surface thats cooled by water).. This is even worse than using it for your drysuit..

One thing I will agree with you is that Helium "feels" colder when being breathed because it absorbs temp much quicker, but body core temperature changes less..

 

[PaulSmithTek]

Yes You are correct diving in Super Light 27. So yes it does carry heat away from head alot faster. So I was correct in my theory, but also wrong about scuba. I know that the inflator valve on the dry suite feels like ice water comming into the suite when pushed with Heliox. Thanks for everyone feed back.