Is there a Nitrogen Loading Equilibrium Point?

[dmoore19]

Thanks for that explaination. That is a great way of thinking about it.

 

[Blackwood]

limit your... caffeine intake

Then I'm screwed.

 

[Teamcasa]

For my classes I use the following analogy to explain the ongassing/offgassing process ...

Excellent example in the full post. Thanks for posting it.

Just to emphasize how important this part is, I quote it again but will add, ascend as slow as possible.

So there really is no hard answer to your question ... my best advice for a 5-dive a day liveaboard is to use nitrox (if it's an option), limit the time you spend deep, spend a longer than normal time in the shallows on each dive, drink lots of water or other hydrating fluids, limit your alcohol and caffeine intake, and get a good night's sleep between those 5-dive days.

 

[GrandpaScuba]

The equilibrium point is different depending on what depth you are at. This is what Henry's Law is all about. If you stay an any depth long enough, you will reach an equilibrium or saturation point. If you stay at that depth after that, you will not take on or give off any additional nitrogen. If you ascend to a lesser ambient pressure, you will begin releasing nitrogen, until you reach the saturation point for that depth. If you descend, you will begin to take on more nitrogen until you reach the saturation point for that depth.

As far a using this information to plan your dives, that is exactly what your dive computer is doing.

 

[GrandpaScuba]

Some could say that it's 33 fsw. Because that is where the pressure gradient is at a 2:1 ratio, and there is no - NDL for less than 33 feet. However...

The Doppler ND Dive Table has an NDL of 205min for 30fsw and 245min for 25fsw.

 

[h2odragon1]

It's called saturation diving.
The Navy teaches this to their divers.
It involves depth/time. At a given depth your tissues become saturated with N2 and will not load any more. You can work at those depths for days on end, but you must stay at that relative depth for the work period, (IE; if you surface, you must end the dive in a chamber at that depth until you return to that working depth.) I'm not definite about this, but I think you need 10 hours of deco for every hour at a given working depth.
Is it worth it? For the work the Navy does, they feel it is.

 

[gcbryan]

It's called saturation diving.

The Navy teaches this to their divers.

It involves depth/time. At a given depth your tissues become saturated with N2 and will not load any more. You can work at those depths for days on end, but you must stay at that relative depth for the work period, (IE; if you surface, you must end the dive in a chamber at that depth until you return to that working depth.)

I'm not definite about this, but I think you need 10 hours of deco for every hour at a given working depth.

Is it worth it? For the work the Navy does, they feel it is.

This is not correct. Once you reach saturation there is a fixed obligation for that depth that does not increase with additional time spent there.

That is the whole point of saturation diving. Once you've incurred that long fixed obligation it doesn't get greater so you might as well stay there for a long time if the project requires it.

 

[Crowley]

Is it possible to get bent in 20 ft of water? Yes - in fact if you look at the RDP, the most "dangerous" pressure groups for a single dive are shallow dives for long periods of time - hence the WXYZ rules for mimimum surface intervals. This is because the so called "slow" compartments take on gas very slowly, but also release it very slowly also - hence repetetive shallow dives for extended periods of time can be misleadingly believed to be "safe". In theory, you are still on-gassing even whilst making a safety stop at 5 metres after a sixty minute dive.

An article I read from Suunto suggested 6 CESAs from 9 metres (45 ft) is enough to significantly increase a person's pre-dispostion to DCS. A number of rapid ascents caused during training dives could easily have led the instructor in this case to get bent.

Given that most instructors in resort areas can be spending 3 or more hours a day in the water - and longer in some cases - their risk of DCS becomes more significant.

I also know of one case where a girl got bent during a Discover Scuba Diving experience (max depth of 6 metres) due to a Patent Foramen Ovale (hole in the heart) - a medical condition with potential problems for divers (I won't go into it here).

Full sat diving is not for the faint of heart and, as a number of wheelchair-bound full-sat oil rig divers from the 70s are finding out, not especially good for your health.

Happy decompressing,

C.

 

[fisheater]

The simple answer is "yes," there is an equilibrium point, but it's not depth, it's time.

Stay long enough at any depth (or altitude) and your tissues will on or off gas (depending upon which direction from which you came) to reach an equilibrium with the ambient pressure.

 

[captain]

The simple answer is "yes," there is an equilibrium point, but it's not depth, it's time.

Stay long enough at any depth (or altitude) and your tissues will on or off gas (depending upon which direction from which you came) to reach an equilibrium with the ambient pressure.

I am not sure I get the point of the OP question but as fisheater pointed out equilibrium or saturation is based on time at a particular depth whatever that depth may be and usually is considered to be 24 hours. If you stay at 100 feet for 24 hours you are at equilibrium for 100 feet. Descend to 150 feet you are ongassing until you reach equilibrium at 150 feet after another 24 hours. The same happens in reverse when moving to a shallower depth.