hotx

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omar once bubbled...
We routinely use 30/30 which is sometimes considered HOTx.
What is your definition of HOTX and when would 30/30 not be considered HOTX?

I prefer it to 32% EANx.
Why? I haven't done the math on this, but doesn't reducing the N by 11% in the mix substantially improve the END? What advantages does adding this much He to the mix offer? Beyond price, reduced non-deco limits and R values, what disadvantages?

It can also be dove with nitrox computers (horrors ;-) set to 32% as well.
What is the formula used to arrive at this 30/30 = EAN32 equivalency?

Thanks, in advance!

Steven
 
We use 30/30 for dives to 120'
We subtract 15% for our EAD.

We reckon oxygen the narcotic equivalent of nitrogen.
We actually suspect that it is more so.
At least it *feels* that way.
 
I don't have a definition for HOTx. I don't worry about it.

I have been moving to a set of standard mixes for my dives. The EANx has been relegated to places I can't get He or warm water, high viz, fish dives.

ummm taking 30% of the N out is better than offseting it with the added O2. Both are considered to be narcotic.

By R values I assume you mean thermal properties. There is no significant difference between air and 30/30 as far as thermal properties for breathing. The higher thermal conductivity of He is offset by the lower heat capacity so the sum is about even when comparing heat loss from breathing. I actually went through the math on one of the threads a long time ago. The helium mix actually had a SLIGHTLY less heat loss.

As, I said you can actually dive it as 32% EANx on the Alladan dive 'puters. So in effect there is no NDL disadvantage for single tank dives.

Running lots of scenario's on dive planning software and experience has found that this works for me.

omar
 
ScubaDan once bubbled...
The reason I ask was because I was at the abysmal diving web sight and watched the intro and one of the gases that was used on the simulated dive to 330fsw was hotx.

Thanks for the help.

http://www.abysmal.com/english.html

I think it's a net intro

give us a better link to the exact article, i would be interested in reading it. I know what hetox is could that be what they where talking about for deep dives
 
Uncle Pug once bubbled...
We use 30/30 for dives to 120'
We subtract 15% for our EAD.

We reckon oxygen the narcotic equivalent of nitrogen.
We actually suspect that it is more so.
At least it *feels* that way.

PUG I would be interested to know more about the narcotic effects of Oxygen and how it compares to N2

Know I do not consider O2 toxicity as a narcotic effect
 
No article that I know of, just the INTRO movie that used Hotx and I just wanted to know what it was.

Thanks for the help.
 
I found this on the internet.

An Introduction to HOTx
Trimix is a breathing mixture consisting of oyxgen, helium and nitrogen. Traditionally, Trimix has been used as a deep diving gas as it is less narcotic at depth than air or nitrox. Usually these mixes contained an oxygen percentage less than normoxic (less than 21% oxygen). The oxygen content was kept low due to the possibility of CNS oxygen toxicity problems when breathing partial pressures of oxygen greater than 1.6 atmosopheres.

The technical diving commumity has long recognized the risks associated with conducting deep dives while breathing narcotic mixes. More recently that recognition has been extended to include intermediate deep dives (100 to 170 feet seawater). To reduce the associated risks many divers are using Trimixes containing 21 percent and higher fractions of oxygen.

These intermediate deep diving gases are known by a variety of names. Call it "Normoxic Trimix," "Helitrox" or "High Oxygen Trimix" (HOTx), the principle is the same. By displacing some of the nitrogen content with helium the gas is less narcotic, thus reducing risk to the diver.

Technical diving courses providing training in the use of high oxygen trimix are gaining popularity. Via these programs it is now possible to climb the training ladder to the Trimix level without having to be exposed to deep air diving. Due to the special considerations involved in conducting these types of dives because of the addition of helium to the mix, divers should seek specialized training before attempting to execute HOTx dives.

Currently, HOTx is used almost exclusively for stage-decompression diving. As such it is considered a technical diving gas. Recently, however, a great deal of experimentation has been being done concerning using the gas for no-stop diving. In the not too distant future HOTx may become a mainstream recreational diving gas for no-stop dives in the 100 to 130 foot range.


http://www.sportdiverhq.com/hotx.htm
 
It seems like a waste of good helium to use it on NDL diving, or diving where narcosis is not a factor.
 
I missed your post to me in this thread a page back.

There is controversy about the narcotic effects of oxygen. While its lipid solubility would suggest that it has greater narcotic potential than nitrogen that is not necessarily the case.

Since there is no definitive word on whether it is or it isn't...

We regard, for our purposes, O2 to be as narcotic as nitrogen... and subjectively it *feels* that it is so.
 
https://www.shearwater.com/products/perdix-ai/
http://cavediveflorida.com/Rum_House.htm

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