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hi

i am ready to buy my first set of twins, do i get them o2 clean or just run them with air.

what do you use or do you have two sets.

regards

chris
 

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<font color='#000F22'>I run my twins with a PPO2 of 1.45 for my expected max depth on a known site / wreck, as your only at that max depth for a relatively short time the av ppo2 would be about 1.3.

If I'm diving with the deco (80%) bottle, then I'll usually use air & deco on the rich mix from 9m - I have the facility to switch gases during dive. This also helps keep the O2 costs down .

I'd recommend you get them O2 cleaned, and try both options, the higher O2 will give you a longer run time or allow three shallow non deco dives.

HTH

gareth
 

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<font color='#000080'>Personally, I think if you're going to dive twins it makes a lot of sense to dive nitrox. In fact, it makes sense for anyone to dive nitrox. It's a safe gas, and used properly, can make diving a whole lot better and easier. The difference in how tired I am after diving is sufficient for me to justify the cost. I can go for a dive inthe morning, and work all afternoon if I have to. This wasn't possible before. I always used to sleep especially after 2 or 3 dives in a day.

If you don't have a nitrox ticket, get one soon. TDI courses are available after entry level training, and you'll get a good knowledge of the gas as well as diving it a fair bit. I see nitrox as one of the first things to reccomend to people, right after O2 admin and rescue skills.

I effectively have as many sets as I like, as the uni club has a lot of tanks available to me, but non e are O2 clean, so I tend to use my twins for any deeper diving where the advantage of the gas makes a big difference for me. If it's inconvenient to top off the twins, I can use a club tank or twin them up. Works nicely for me, but it's always air in them.

Hope this helps

Digs.
 

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If you are buying them new it's worth having then o2 clean so you can chose nitrox or air. I usually dive on air because my local dive shop nitrox was really expensive but would use nitrox all the time if it was cheaper. Local dive shop is now closed so i just usewhatever fill i can get.
jules
 

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Air sucs.  Dived twins on air today and raced up 27mins deco.  Accelerated off with 79% but had to hang around to not bend computer...

Nitrox is the ONLY way ahead iMHO.  O2 clean gives you the option...
 

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Either air in my twins or trimix, I've never had nitrox in them but they are or were O2 clean.  The cost of a 32% fill would be £12.

Paying to have a new cylinder O2 cleaned is a bit of a con as they should already be clean and only need the stickers putting on.

Cheers

Simon
 

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<font color='#0000FF'>Go O2 clean.

At least you've got the option if u need it. Trox does have mega benefits in the 25-40m range.

stu.
 

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Twins = extended bottom time
Nitrox = extended bottom time with less / no deco

It makes sense to use Nitrox in twins up to the 50m mark and especialy in the 30-40 zone. TDI entry level Nitrox is a test only with a bit on analizing a tank and costs about £79.00. Well worth it IMHO

ATB

Mark Chase
 

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cheers guys

got a set off ebay o2 clean for £210 sh faber 232 12s with custom diver bands and a twin boot, not sure on the make of manifold though althought i was told its not a cheap beaver one.

regards chris
 

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Chris
mine are 02 clean and I run Nitrox, try to keep the PP at 1.4 for diving which makes the diving a lot less exhausting.

Mark
50m on Nitrox?
30/40m ?

I though the max benefits were in the 15/25m range.

50m would give 23% 02, below 40 wouldnt tri-mix be much better after all the N PP would still be likely to cause narcosis.

Matt
 

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Nitrox for me + 80% deco (if required).

Pushes the PPO2 a bit high sometimes but I have the safety net of a FFM.
 

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[b said:
Quote[/b] (MATTBIN @ May 04 2004,10:20)]Mark
50m on Nitrox?
30/40m ?

I though the max benefits were in the 15/25m range.

50m would give 23% 02, below 40 wouldnt tri-mix be much better after all the N PP would still be likely to cause narcosis.
If you think in terms of run time as aposed to no decompresion time you can see the advantage:


All these are on a 20/85GF

40m for 40min on air 130min run 88min deco
40m for 40min on 28% 93 min run 50min deco
38min les deco

50m for 35min on air 163min 125min deco
50m for 35mn on 24% 137min 99min deco
26mn less deco

I realise the PPo2 fr 24 is 1.44 but the CNS for the whole dive is only 28% so its not exactly cutting edge stuff.
Lets face it you wont do the whole dive with your belly in the gravel.

Trimix is just Nitrox + Helium the 02 percentage is unafected by the He percentage it is what it is. The Helium will alter the shape of the deco but it doesent affect the CNS and it dosent have a great impact on the total deco time unless you are using a lot of it.

50m for 35m 24/20 Trimix 136min with 98min deco

1 mins less deco for the He.  

50m for 35m 24/30 Trimix 154min with 116min deco

18mins more deco due to the 30% He

However using a rich deco mix can sort this out:

50m for 35min 24/30 Trimix 32% and 80% for deco 73min 34min deco

50m for 35min 24% Nitrox 78min 39min deco

Te High o2 pushes out the He quickley so it actualy reduces the deco

All good fun

Mark Chase
 
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