Khalil Rodriguez
Registered
If trimix allows divers to go to 330 feet, what gas/mixture is used to go to 400 feet?
If trimix allows divers to go to 330 feet, what gas/mixture is used to go to 400 feet?
- Thread starter Khalil Rodriguez
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What's your diving background? Not too keen on trolls around here
OP
Khalil Rodriguez
Registered
Just starting
You need to concentrate on things 30 metres and above, with air or enriched air and learning how to dive under these conditions safely. There's a lot to learn before you go beyond this.
trimix, but just with a lower percentage of Oxygen. But I agree with Nettie, it is a bit early in your learning process 
ajduplessis
Contributor
The thing to remember is that Trimix isn't just one set of gases. Same goes for Nitrox Heliox.
Trimix will have 3 main components, O2/N2/third gas (usually helium). You then adjust the ratios depending on the depth that you are diving. Obviously some of the mixes can't be used in shallow water, so you will have stage bottles for those.
Nitrox is similar, but you don't add a third gas. You just increase the O2 and decrease the N2. PpO2 now becomes very important, so generally recreational divers don't go deliver than 40m on Nitrox.
Heliox is currently mainly used in the commercial diving industry, but you are starting to see it in recreational diving. You get rid of the nitrogen completely and just have O2 and Helium. PpO2 is again a factor, but you are technically not limited in depth. As an example, if you dive to 300m/990f on Heliox you will be using a mix of 99% helium/1% O2. For recreational purposes this is pretty much impossible, but in the commercial diving industry they control your mix from topside.
(I'm an engineer at a commercial diving equipment manufacturer)
Trimix will have 3 main components, O2/N2/third gas (usually helium). You then adjust the ratios depending on the depth that you are diving. Obviously some of the mixes can't be used in shallow water, so you will have stage bottles for those.
Nitrox is similar, but you don't add a third gas. You just increase the O2 and decrease the N2. PpO2 now becomes very important, so generally recreational divers don't go deliver than 40m on Nitrox.
Heliox is currently mainly used in the commercial diving industry, but you are starting to see it in recreational diving. You get rid of the nitrogen completely and just have O2 and Helium. PpO2 is again a factor, but you are technically not limited in depth. As an example, if you dive to 300m/990f on Heliox you will be using a mix of 99% helium/1% O2. For recreational purposes this is pretty much impossible, but in the commercial diving industry they control your mix from topside.
(I'm an engineer at a commercial diving equipment manufacturer)
fsardone
Solo Diver
Not enough knowledge on too many things might give the impression things are easy. One year ago doc deep died ... because he knew too little of too many things.
A diver diving on heliox starts having HPNS issues, which are avoided by compressing at a very slow rate ... which is not compatible with bounce dives but only with saturation diving ...
Deep diving requires a lot of study and I would recommand baby steps and many dives before going 3 digit in meters ... or beyond 300' and that is a very serious depth anyway ... with alot of logistic associated.
Somebody asking the op question should not be offered too much knowledge ... out of a structured training course, in my view.
Very well said. Training is very important, and I would add, with ease of training today, that experience even more so. Under no circumstances should someone new to diving try diving deeper than what their qualification say that can dive to.
I've been in the commercial game for 10 years now, and even I wouldn't just jump in the water and head to triple digits. I know all the theory, can do most of the important calcs in my head, but I also know that I have not yet received any formal training on diving that depths.
Coming back to the op's question, I don't think it is wrong to answer it. Nowhere did he indicate that he is planning on diving with anything else than regular air. Being curious is a good thing. By giving someone the right information, and not chasing them away for asking questions above their qualification, you encourage that person to read more and learn more. Hopefully that encourages them to pursue further qualifications, and hopefully one day join the advanced technical diving community as a well rounded and knowledgeable diver.
I don't think it will hurt to answer the question. I don't get the feeling it is to facilitate a dive to 400fsw... If you assume a 130ft END (equivalent to diving air at 130ft) and a PPO2 of 1.4, You're looking at 11/62 (ish). 11% Oxygen and 62% Helium.
There are some good apps that you can download so this is hardly top secret information.
That said, to do this type of dives, one needs the training and - especially - the experience. There are no shortcuts and you can kill yourself if you don't respect the procedures, planning, training, depth and everything else related to Technical Diving. So get wet, work your way up the chain and take your time - and enjoy yourself. But remember, Technical Diving is not a competition sport. It's not about the numbers but more about the dives themselves and what you will experience.
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