Switching gasses with D9

[ajduplessis]

the old D9 manages also only one tank.
when you're diving with multiple tanks, it's a very technical dive, so you plan your dive.
you know how much time you stay at a deep, you know how much mix you will use, you know when you switch to another mix, you plan with a secure consumption.
if you dive your plan, you don't need to look at your pressure gauge so, why manage 8 wireless transmitters ?

Dude, firstly since you know so much about tech diving you would know you don't exceed PO2 of 1.4 for bottom gasses, its a rule not an opinion as posted in your previous response. Why do you want to load CNS OTU? Are you aware that these units accumulate 4X faster with a PO2 above 1.4 !?! It is vitally important that any EAN diver manage CNS as it generally gives no warnings and have the ability to kill you!! TDI normoxic qualified, are you sure???

Secondly, please explain why you would not check your pressure during dives (see bold)

 

[DuboisP]

Dude, firstly since you know so much about tech diving you would know you don't exceed PO2 of 1.4 for bottom gasses, its a rule not an opinion as posted in your previous response. Why do you want to load CNS OTU? Are you aware that these units accumulate 4X faster with a PO2 above 1.4 !?! It is vitally important that any EAN diver manage CNS as it generally gives no warnings and !! TDI normoxic qualified, are you sure???

Secondly, please explain why you would not check your pressure during dives (see bold)

PpO2 1.4 is a security rule, not a physical rule.

military divers use PpO2 2.3 on CCR. OK, they're young and in better physical form than me.

if 1.6 is a problem, why allow it for deco mix ?
on the first linked document, PpO2 limit was 1.8 ...

> four times faster ? check your tables.... OTU/min at 1.4 is 1.63. OTU/min at 1.6 it's 1.92
CNS at 1.4 is 0.65%/min, 154min/day. CNS at 1.6 is 2.22%/min, 45min/day.


if you know REPEX tables, the allowed OTU by day during some days, the maximum OTU during one day is 850 OTU.
at PpO2 1.6, you store 1.92 Otu/min, so to accumulate 850 OTU, you need to be exposed 442 minutes at 1.6 , so 7h22.

On other references, usually recommanded, i have 45 min at 1.6 for one dive, 150 min for one day.
Same 45 min at 1.6 to have a CNS of 100%.
Generally, only cave divers in Open Circuit or Closed Circuit can be exposed to these values, and it's not uncommun to have a CNS of 800% . Are they dead ?

During my latest trimix dive, 190ft 15min bottom, my OTU was 52, my CNS was 20% (Tx 20/27, EanX42, EanX95)
To get a CNS of 100%, i need to stay 75 min bottom, near 3 hours total. But i will be out of gaz.

http://www.oceanwreckdivers.com/images/tolerating_exposure_to_high_oxygen_levels.PDF
Teaching Oxygen Tracking Article 95-2
NOAA Diving Manual


I didn't tell i don't look at my pressure gauge, i told that if your plan your dive and dive your plan, you know in advance how much gaz you need and how much you use, so it's not really needed to look at it.

 

[ajduplessis]

I wonder why you now refer to a security rule. I though there was no rule!!! :mooner:

My apologies 2.22%/0.65%=3.415 not 4X Faster :mooner:

“During my latest trimix dive, 190ft 15min bottom, my OTU was 52, my CNS was 20% (Tx 20/27, EanX42, EanX95)”
You dive 190ft form 15min on 20/27 resulting in a PO2=1.36. Why are you diving one way and advocating ridiculous/dangerous exposures on the other?
Why are you bounce diving(15min)???
” To get a CNS of 100%, I need to stay 75 min bottom, near 3 hours total. But I will be out of gaz”

Have you actually completed this dive like this, or the math? You only need around 50min BT to get to 100%, or don’t you use that lovely “stroke mixes” you blended for deco?

You clearly don't know the difference between CNS and OTU.

1) CNS at 1.6 is 2.22%/min, 45min/day
then
2)at PpO2 1.6, you store 1.92 Otu/min, so to accumulate 850 OTU, you need to be exposed 442 minutes at 1.6 , so 7h22 - No you can't. Single 1.6 exposures is only 45min. What point are you trying to make here!!!

By having a CNS of 800% you WILL exceed your OTU resulting in lung damages (pulmonary oxygen toxicity).

Please stop advocating dangerous diving habits on a public forum. You are supposed to lead and give guidance.

 

[DuboisP]

I wonder why you now refer to a security rule. I though there was no rule!!!
:mooner:

My apologies 2.22%/0.65%=3.415 not 4X Faster :mooner:

“During my latest trimix dive, 190ft 15min bottom, my OTU was 52, my CNS was 20% (Tx 20/27, EanX42, EanX95)”
You dive 190ft form 15min on 20/27 resulting in a PO2=1.36. Why are you diving one way and advocating ridiculous/dangerous exposures on the other?
Why are you bounce diving(15min)???
” To get a CNS of 100%, I need to stay 75 min bottom, near 3 hours total. But I will be out of gaz”

Have you actually completed this dive like this, or the math? You only need around 50min BT to get to 100%, or don’t you use that lovely “stroke mixes” you blended for deco?

You clearly don't know the difference between CNS and OTU.

1) CNS at 1.6 is 2.22%/min, 45min/day
then
2)at PpO2 1.6, you store 1.92 Otu/min, so to accumulate 850 OTU, you need to be exposed 442 minutes at 1.6 , so 7h22 - No you can't. Single 1.6 exposures is only 45min. What point are you trying to make here!!!

By having a CNS of 800% you WILL exceed your OTU resulting in lung damages (pulmonary oxygen toxicity).

V-Planner 3.89 par Ross Hemingway,
VPM code-programme par Erik C. Baker.

Modèle de décompression: VPM - B

PROFIL DE PLONGÉE
Intervalle de surface = 1 jours 0 hr 0 min.
Altitude = 0ft
Conservatisme = + 2

Desc à 190ft (1) Trimix 20/27 100ft/min Descente.
Niveau 190ft 73:06 (75) Trimix 20/27 1.35 ppO2, 117ft ead, 130ft end
Rem. à 120ft (77) Trimix 20/27 -33ft/min Remontée.
Palier à 120ft 0:53 (78) Trimix 20/27 0.93 ppO2, 70ft ead, 79ft end
Palier à 110ft 2:00 (80) Trimix 20/27 0.87 ppO2, 63ft ead, 71ft end
Palier à 100ft 4:00 (84) Trimix 20/27 0.80 ppO2, 56ft ead, 64ft end
Palier à 90ft 5:00 (89) Trimix 20/27 0.74 ppO2, 49ft ead, 57ft end
Palier à 80ft 4:00 (93) Nitrox 42 1.44 ppO2, 50ft ead
Palier à 70ft 4:00 (97) Nitrox 42 1.31 ppO2, 43ft ead
Palier à 60ft 6:00 (103) Nitrox 42 1.18 ppO2, 35ft ead
Palier à 50ft 9:00 (112) Nitrox 42 1.06 ppO2, 28ft ead
Palier à 40ft 12:00 (124) Nitrox 42 0.93 ppO2, 21ft ead
Palier à 30ft 18:00 (142) Nitrox 42 0.80 ppO2, 13ft ead
Palier à 20ft 16:00 (158) Nitrox 95 1.52 ppO2, 0ft ead
Palier à 12ft 39:00 (197) Nitrox 95 1.29 ppO2, 0ft ead
Surface (197) Nitrox 95 -33ft/min Remontée.

Le dégazage commence à 145.4ft

OTU pour cette plongée: 265
CNS Total: 102.8%

> Single 1.6 exposures is only 45min.
> By having a CNS of 800% you WILL exceed your OTU resulting in lung damages (pulmonary oxygen toxicity).

no
to have a CNS of 800% at PpO2 1.6, you need to stay 800% / 2.22% = 360.36 min
your OTU will be 360.36 min * 1.92 = 691.89 OTU
The recommanded limit is 850 OTU for one day, 1400 for 2 days

i gave you some references.
give me your references proving automatic damages to lungs when exceeding 100%, and automatic nervous problems when exceeding PpO2 1.6 more than 45 minutes.

CNS : central nervous system. Paul Bert. Neurologic toxicity
OTU : oxygen toxicity unit. Lorrain-Smith . Pulmonary toxicity

These 2 counters are separate

My confusion ?

 

[ianr33]

Why do you want to load CNS OTU?

What's CNS OTU ?

By having a CNS of 800% you WILL exceed your OTU resulting in lung damages (pulmonary oxygen toxicity).

That statement makes NO sense at all. Have you done a nitrox course?

 

[ajduplessis]

give me your references proving automatic damages to lungs when exceeding 100%, and automatic nervous problems when exceeding PpO2 1.6 more than 45 minutes.

Your TDI Normoxic manual would be a good place to start. Unless the manual recommends bottom PO2 greater that 1.4 and deco greater than 1.6

I still would like to know why you dive with bottom PO2 less than 1.4 and deco on less than 1.6 and talk something different????

 

[ianr33]

if 1.6 is a problem, why allow it for deco mix ?
on the first linked document, PpO2 limit was 1.8 ...

My understanding is that at deco you hopefully aren't working too hard and as the gas density is low it's pretty easy to remove CO2.

At depth you may well be working hard .Add a greater Work of Breathing due to high gas density (especially on non helium mixtures) and you have the potential to increase CO2. High CO2 and high pO2 together are a real bad combination.

Although I personally would have no problem hitting a pO2 of 1.6 at depth for a minute or two,I certainly would not plan an entire dive like that,especially if it involved working hard.

 

[DuboisP]

Your TDI Normoxic manual would be a good place to start. Unless the manual recommends bottom PO2 greater that 1.4 and deco greater than 1.6

I still would like to know why you dive with bottom PO2 less than 1.4 and deco on less than 1.6 and talk something different????

i don't confuse, as you, medical and physical facts, and security facts.

bottom 1.4 and deco 1.6 are secure and good recommendations, but i don't argue, as you, it's an absolute truth.

 

[DuboisP]

i did PpO2 of 2.0 a couples of minutes.
not relaxing at all.