Who's using 100% O2 for deco?

[MXGratefulDiver]

Maybe for you. Some of us go on more serious dives.

:shocked2: ... I think James' dogma just got run over by a karma ...

... Bob (Grateful Diver)

 

[Jax]

:shocked2: ... I think James' dogma just got run over by a karma ...

... Bob (Grateful Diver)

:spit:

 

[ucfdiver]

I wouldn't take an al40 filled with anything. All my stages are 80's. No one ever died from having too much gas.

OK so now we're back to 51cu ft @ 2kpsi of an AL80. That's 79 minutes at 20ft, enough for a 20min dive @ 300ft. Or assuming deep air because no booster, that's enough deco gas for 1.5hrs at 180ft.

Sounds like your instructor should have focused a bit more on diving logistics and less on under water basket weaving and regulator screwing-in.

 

[MXGratefulDiver]

No one ever died from having too much gas.

sometimes you just wish they would ...



... Bob (Grateful Diver)

 

[Ste Wart]

OK so now we're back to 51cu ft @ 2kpsi of an AL80. That's 79 minutes at 20ft, enough for a 20min dive @ 300ft. Or assuming deep air because no booster, that's enough deco gas for 1.5hrs at 180ft.

Sounds like your instructor should have focused a bit more on diving logistics and less on under water basket weaving and regulator screwing-in.

That is logistics. I get one fill and it lasts the weekend.

And it was underwater shadow boxing we practised :mooner:

 

[Jax]

:spit:




(Dang fortunate it's lunch time!!!!)

 

[Gilldiver]

What kinds of dives are you doing where you'd need more than 60cf of O2 (and don't need a booster for back gas)?

You might be surprised at how few shops have boosters. In New England I know of only 2 or 3.

I have mixed many twin sets of 60% He without a booster by PP, you need at least 4 - 300 cubic foot tanks in cascade to do it, and it is a pain in the ass, but can be done - and I don't waste gas getting down to 200-300 psi in the first tank in the cascade. Sometimes we target 17/60, dive rule of 1/3's and top off with air to get a 21/20 mix for a second dive down to 160 or 180 out of one fill. That is how you can handle the logistics without a booster

 

[Rainer]

I dived for a few years in New England (and visited several shops with boosters, but that's besides the point). You can also get a bit above 2000psi just transfilling O2 using the same method you propose for mixing back gas. That's still a TON of O2 in an AL80, that's all.

You might be surprised at how few shops have boosters. In New England I know of only 2 or 3.

I have mixed many twin sets of 60% He without a booster by PP, you need at least 4 - 300 cubic foot tanks in cascade to do it, and it is a pain in the ass, but can be done - and I don't waste gas getting down to 200-300 psi in the first tank in the cascade. Sometimes we target 17/60, dive rule of 1/3's and top off with air to get a 21/20 mix for a second dive down to 160 or 180 out of one fill. That is how you can handle the logistics without a booster

 

[Atticus]

Y'know .. you can always buy your own booster, they're not *that* expensive compared to everything else in this hobby. Particularly if you divide the cost across a couple of tech diving buddies.

Personally my answer to a weekend of diving is to just bring two alu40's, whether they be filled to 2k or 3k.

 

[Slamfire]

Once you get to a real world execution 80% or 100% are not much different from each other. Consequently, though I marginally prefer 100%, I'll go with whatever is most convenient at the time to get me the closest to a full tank.

Settings: GF=30-80
===================================================
DESC:200ft for 03:20 [ 3] on Trimix 18/45
DIVE:200ft for 25:00 [ 28] on Trimix 18/45
ASC :120ft for 02:39 [ 31] on Trimix 18/45
ASC :110ft for 00:20 [ 31] on Nitrox 34
DECO:110ft for 00:40 [ 32] on Nitrox 34
DECO:100ft for 01:00 [ 33] on Nitrox 34
DECO: 90ft for 01:00 [ 34] on Nitrox 34
DECO: 80ft for 01:00 [ 35] on Nitrox 34
DECO: 70ft for 02:00 [ 37] on Nitrox 34
DECO: 60ft for 02:00 [ 39] on Nitrox 34
DECO: 50ft for 04:00 [ 43] on Nitrox 34
DECO: 40ft for 05:00 [ 48] on Nitrox 34
DECO: 30ft for 07:00 [ 55] on Nitrox 80
DECO: 20ft for 10:00 [ 65] on Nitrox 80
DECO: 10ft for 18:00 [ 83] on Nitrox 80

Gas estimate based on Dive RMV =0.7, deco RMV =0.6cuft/min
Nitrox 80 : 31.7cuft
Trimix 18/45 : 143.9cuft
Nitrox 34 : 29.3cuft
Oxygen Toxicity - OTUs: 99 CNS: 39%


*****************************************


Settings: GF=30-80
===================================================
DESC:200ft for 03:20 [ 3] on Trimix 18/45
DIVE:200ft for 25:00 [ 28] on Trimix 18/45
ASC :110ft for 03:00 [ 31] on Trimix 18/45
DECO:110ft for 00:40 [ 32] on Trimix 18/45
DECO:100ft for 01:00 [ 33] on Trimix 18/45
DECO: 90ft for 03:00 [ 36] on Trimix 18/45
DECO: 80ft for 02:00 [ 38] on Trimix 18/45
DECO: 70ft for 02:00 [ 40] on Nitrox 50
DECO: 60ft for 02:00 [ 42] on Nitrox 50
DECO: 50ft for 04:00 [ 46] on Nitrox 50
DECO: 40ft for 05:00 [ 51] on Nitrox 50
DECO: 30ft for 06:00 [ 57] on Nitrox 80
DECO: 20ft for 11:00 [ 68] on Nitrox 80
DECO: 10ft for 20:00 [ 88] on Nitrox 80

Gas estimate based on Dive RMV =0.7, deco RMV =0.6cuft/min
Nitrox 80 : 33.1cuft
Nitrox 50 : 19.8cuft
Trimix 18/45 : 159.9cuft
Oxygen Toxicity - OTUs: 106 CNS: 44%


*****************************************

Settings: GF=30-80
===================================================
DESC:200ft for 03:20 [ 3] on Trimix 18/45
DIVE:200ft for 25:00 [ 28] on Trimix 18/45
ASC :110ft for 03:00 [ 31] on Trimix 18/45
DECO:110ft for 00:40 [ 32] on Trimix 18/45
DECO:100ft for 01:00 [ 33] on Trimix 18/45
DECO: 90ft for 03:00 [ 36] on Trimix 18/45
DECO: 80ft for 02:00 [ 38] on Trimix 18/45
DECO: 70ft for 02:00 [ 40] on Nitrox 50
DECO: 60ft for 02:00 [ 42] on Nitrox 50
DECO: 50ft for 04:00 [ 46] on Nitrox 50
DECO: 40ft for 05:00 [ 51] on Nitrox 50
DECO: 30ft for 07:00 [ 58] on Nitrox 50
DECO: 20ft for 10:00 [ 68] on Oxygen
DECO: 10ft for 18:00 [ 86] on Oxygen

Gas estimate based on Dive RMV =0.7, deco RMV =0.6cuft/min
Nitrox 50 : 27.8cuft
Trimix 18/45 : 159.9cuft
Oxygen : 23.7cuft
Oxygen Toxicity - OTUs: 110 CNS: 61%