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The Artist formerly known as 'John Duncan'
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<font color='#F52887'>What is it and what is it used for? I am TDI Advanced nitrox and Staged deco qualified and may do the entry trimix next year, but want to know more about it. Is it expensive to use? (twin 12's) What equipment requirements? Etc.....
 

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It's trimix that you can breathe at the surface without passing out from hypoxia. It means you don't need to have a separate travel gas to get you to a depththat it becomes breathable.
 

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The Artist formerly known as 'John Duncan'
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<font color='#F52887'>so, what maximum depth is it designed to be used at? what mix is it? O2/He/N2...
 

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<font color='#000F22'>The normal max is 18/35 and that'll do you nicely at 60m which is the extent of the ticket.

You'll need twins and two stages for the course with suitable regs for same.

Yes, helium is expensive but good for remembering dives with  
 

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Normoxic means just that - normal or the same as air in its percentage of oxygen. I think a normoxic qualification allows you to use mixes down to around 18% depending on the agency. As Dom said, the percantage of oxygen is above that critical 10-12% giving you a ppO2 of above 0.1 on the surface and is therefore still life supporting.

The addition of helium then of course gives you an equivilent narcotic depth (END) shallower than your diving depth depending on the amount of helium in your mix. Helium does also have its own set of rules for deco etc

The depth it is used at is limited (as with nitrox) by the ppO2. Normixic trimix, with say 21% O2 will have a ppO2 of 1.4 at about 54m (of there abouts, off the top of my head). Depending on your agnecy, that is about the limit.

As to equipment, it is by nature a technical dive, I wouldn't expect anyone to jump in with a single trimix cylinder with a pony. I would used twins and probably side slings with deco gas.

In answer to your question on blending. You add the helium, add the oxygen (if required) and then top up with air. As far as I know, people don't blend using nitrogen only (I am prepared to be corrected though)

HTH

Paul
 

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<font color='#8D38C9'>Not sure you need two stages for a course, have seen people doing it with one and the tdi manuals tables are written for just using ean50 as deco gas. You can also put as much he in as you want as long as you keep to 18 o2.

But I think most people stick to 18 / 30 to begin with, depends on your narcosis tolerence. At 60m on 18/30 I was narced so should of used a higher he mix. But then Im a big girls blouse!!

I might be wrong about the above as Im still waiting for the card which has the parameters on it. Might also depend on the instructor. I used 2 stages on my course with ean32 and 100% 02.
Might also be different between iantd and tdi, i did mine with tdi.

so this is probably not much help.
 

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3 posts all at the same time - from people who have a bit more experience! I think what I have said is still valid

Paul
 

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<font color='#8D38C9'>John,

It can be expensive, if u fill t 12's at a shop prices are between 15 and 50 quid I think so shop around, if u live up north give us a shout.

Plus u need to fill heavy blend nitrox or 02.

Also need an argon bottle and first stage with over pressure valve. A good reel and 25kg dsmb and lift bag. Wing, bakplate and harness. Fairly good cold water regs and a fairly reasonable drysuit. Your gear needs to be in  a reasonable state so it doesnt break at the bottom, unlike all my new gear that always breaks!!!!
For more info try http:\\www.tdisdi.com or http:\\www.dalesdivers.co.uk both have fairly informative sites and probably know what they are talking about, unlike me!!!!!!

 

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The Artist formerly known as 'John Duncan'
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<font color='#F52887'>Thanks everyone. I already dive with twin 12's and 10l sidemounts, 5mm compressed neoprene drysuit, mix of Poseidon jetstreams on my twins and scubapros on my stages, I always dive with a red DSMB, a yellow DSMB, 2 reels and a small buddy reel with a small red DSMB attached. backup torch, computer and timer with a full set of tables with worst case scenarios worked out.so the equipment is not a problem. I have still to think about the costings for the gas and training and make my mind up as to "is it worth it for the diving I do?" and only I can answer this question.
 

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I did normoxic trimix earlier this year with the ITDA at The Underwater Centre Fort William, the instructors name is Simon Townsend.  The course costs £400 and this included all the gas which was always 18/45 bottom mix and 50% and O2 for deco.  ITDA teaches anything you can breathe at the surface is classed as normoxic so in theory you can go down to 16% O2 or 70ish metres which is about the limit of what you want to be doing on twin 12's.  As for the cost of helium I pay 3p a litre at the LDS or 2p if I get a friend to do a garage mix.  The problem I have found getting gas from shops is their definition of normoxic and usually they will only sell gas to their training agency standards, 21% or 18%.

Hope this helps

Simon
 

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A short fat well off crap cave diver. Likes wrecks
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[b said:
Quote[/b] (JohnDuncan @ Oct. 21 2003,10:36)]I have still to think about the costings for the gas and training and make my mind up as to "is it worth it for the diving I do?" and only I can answer this question.
Considering the kit you have just described, I asume you are doing stuff in the 50m range. IMHO it is a very good ticket for this kind of diving. The diferance in doing a 50m air dive and a 50m on 21/20 is masive. Try it you wont go back to air.

Loads of very good divers have died using deep air on wrecks because when it hits the fan the narcosis rush can be fatal. I use Mix on ALL 40m+ UK dives. I pay about £1 per % so a 21/20 costs £20 a 18/40 costs £40.00. Its expensive diving but well worth it in terms of safety and enjoyment of the dive.

Be warned that you must have advanced Nitrox and Deco Procedures before doing a Normoxic Trimix.

On the stage issue you only need 1 stage for deco mix to do the Normoxic course its two stages for full TDI Trimix.

I cant answer the question but I hope you dont mind a freindly shove in a safe direction


ATB

Mark Chase
 

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[b said:
Quote[/b] (Ben @ Oct. 21 2003,10:34)]Plus u need to fill heavy blend nitrox or 02.
<font color='#810541'>Sorry Ben but you just lost me. I am a Tri-mix blender but don't have a clue what you are on about here.  
 

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Unless of course he means the heavier radioactive isotope of oxygen - 18O (how do you do superscript on here?)!! That could be a fun gas to use!  
 


Paul
 

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<font color='#8D38C9'>Im still trying to work out the bubblemaker comment


Hope its not a reference to my youthfull good looks and age. Theres only about four people on YD that are keeping the average age of this site down below OAP status......... its almost YDSAGA.
 
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