Enriched air or Air ?

[Tom]

Having just done my Enriched air course (Nitrox) just wondering how many of us use nitrox regular ? Just got me thinking a little after reading PV post about getting bent at shallow depths during training, also what is the usual protocol for using nitrox, for example if you are using 2 cylinders on a boat dive for example and 1 may be air and the other nitrox 32 which would you use first, its just Ive had some conflicting views on this matter, anyone who has any advice etc I would like to hear it please.

[Ian]

With diving, I usually find I am more tired than with other energetic activities. Personally I feel that during repeated series of dives (e.g. a weeks holiday or a long weekend) I am considerably less tired on Nitrox than on Air.

There is (as yet) no sound medical evidence explaining the above (although none against it either) and not everyone reports the same benefit.

Nitrox adds cost and complexity to dives (not much, but some) so I wouldn't bother unless you either

1) need to dive longer (not really an issue in the UK unless you're talking about using weak nitrox at 30-40m)
2) are very keen to increase your safety margin without shortening your dives
3) Find you are fatigued after diving and experiments prove nitrox helps reduce this

Ian

[EllieCee]

I use Nitrox on every dive, I just vary the mix depending on what I am planning to do, except for when I went down to 40m then it was back to air. The biggest difference I found after doing the Nitrox course was, like Ian says, how less tired I was after every dive. The difference was incredible. Yes, its more expensive, but personally think its worth it and will only dive air now if I'm going really deep, or I can't get hold of Nitrox. ( Like at Stoney on a weekend )

Ellie

[Jenkins]

I can't say diving notrox makes me any less tired.

Now I am now mostly doing deeper dives where the extra bottom time offered by Nitrox really does benefit me so yes I mostly dive with it. However proir to diving twins I never bothered getting my cyllinders O2 cleaned and almost always dived air.

[Phil O]

I tend to dive nitrox as much as possible - 32% as a rule because that gives me the flexibility to dive to around 32m easily. I don't do it to extend bottom time anymore but to give me an element of safety. Having been bent at Stoney on a normal dive on air I prefer to take fewer chances.

I will never dive below 30m on air - I know I nark below this depth so will not risk going down and thinking "...mmmm must take this thing out of my mouth and kiss this crustacean flying past me on a broomstick" .. even though it may be the horniest crustacean ever.

There is no doubt in my mind that diving nitrox makes me less tired though .. even with a stupid o'clock start at Stoney.

[Badknees]

tom it depends what you want to use it for.

1) to make the dive a little safer
2) extend your bottom time
3) used as accelerated deco gas.

If you dive a enriched air ( nitrox) for safety i.e you dive it using standard air tables, by this i mean the within the standad NDL's and depths. Because the gas you breath contains less nasty nitrogen you absorb less, thus reducing the risk of a bend.

If you dive a enriched air ( nitrox) for extended bottom time, you will if dived to the limits you would be in the same position as if you'd dive air.

If you dive a enriched air ( nitrox) for deco then it's used to lower your nitrogen loading quicker, handy if a bacon butty is waiting.

on another note using enriched air over aweek say on holiday will make you feel better.
BK

[Jenkins]

(13-08-2008 08:26 PM)Phil O Wrote:  I will never dive below 30m on air - I know I nark below this depth so will not risk going down and thinking "...mmmm must take this thing out of my mouth and kiss this crustacean flying past me on a broomstick" .. even though it may be the horniest crustacean ever.

LOL
Like you once past 30m I certainly start to feel the effects of narcosis although in the UK I can cope down to around 35m before adding helium.

Badknees is absolutely correct rearding the three distinct reasons for using enriched air. (although I would suggest that the need for a wee comes higher than the desire for a bacon buttie)

[aquafan]

Is the idea of enriched air to lessen the affect of narcosis? And also to help with accents?

[Badknees]

(13-08-2008 08:36 PM)Jenkins Wrote:  (although I would suggest that the need for a wee comes higher than the desire for a bacon buttie)

the joys of a pee valve

so food first

BK

[Jenkins]

(13-08-2008 08:37 PM)aquafan Wrote:  Is the idea of enriched air to lessen the affect of narcosis? And also to help with accents?

Although adding extra oxygen does reduce the quantity of nitrogen it doesn't appreciably (if at all) reduce the narcotic effect. Adding helium to the mix (Trimix) will reduce the narcotic effect, but that is not a "recreational" gas and is typically only used really deep dives (it's also expensive!).

For the normal recreational (PADI?) diver there are two reasons for using nitrox:
1/ to reduce your nitrogen absorbsion and give you longer bottom times
2/ to reduce your nitrogen absorbsion without increasing bottom time, therefore increasing the safety factor

Badknees third option regarding a deco gas is perfectly valid but only applicable for those doing decompression dives.