Basic CCR question

[wedivebc]

Good question. As far as the nitrogen goes if you are efficent and not blowing bubbles with your CCR you will not be making up any aditional diluent / nitrogen so you are not loading in the tisue.

Say what?!!! What does expelling gas from your loop have to do with tissue absorbsion?

 

[catalina_mike]

The nitrogen is a constant volume or % contained in the diluent gas. So it is logged in your tisue no matter what. The more volume you are adding to the breathing loop you are introducing new / additional amount of Nitrogen that will, due to the effects of pressure will be loaded. This is my understanding of the physics, it may be a small amount and obviously not as fast of loading / exposure as oc but it still increases the Nitrogen as the loop gets a new mix of nitroger rich dil. Your body will store the Nitrogen in the loop so there is only a fixed amount to get loaded in the tisue if you are not adding volume. Let me know if you have any contrary information.

 

[caveseeker7]

I'm lost here, too.

As far as the nitrogen goes if you are efficent and not blowing bubbles with your CCR you will not be making up any aditional diluent / nitrogen so you are not loading in the tisue

Time is a factor on tissue loading. No matter how efficient you dive, your tissues will load.

The nitrogen is a constant volume or % contained in the diluent gas. So it is logged in your tisue no matter what.

Ambient pressure is another factor in tissue loading. Upon ascent you'll start offgassing even though your still breathing N2.

... not as fast of loading / exposure as oc ...

Why would the same amount of nitrogen in the breathing gas at the same depth (i.e. the same pN2) load faster when breathing from OC than CC?

Your body will store the Nitrogen in the loop ...

You mean offgassing into the loop on ascent?

Am I completely misunderstading what you're trying to say, or are you saying something you completely misunderstood. I'm really lost here.:confused2

 

[wedivebc]

The nitrogen is a constant volume or % contained in the diluent gas. So it is logged in your tisue no matter what. The more volume you are adding to the breathing loop you are introducing new / additional amount of Nitrogen that will, due to the effects of pressure will be loaded. This is my understanding of the physics, it may be a small amount and obviously not as fast of loading / exposure as oc but it still increases the Nitrogen as the loop gets a new mix of nitroger rich dil. Your body will store the Nitrogen in the loop so there is only a fixed amount to get loaded in the tisue if you are not adding volume. Let me know if you have any contrary information.

If you are suggesting adding fresh nitrogen via diluent will accelerate N2 ongassing that is not the case. The nitrogen in your loop is a factor of the fixed Ambient pressure - PPO2. For example the PPN2 at 4ata depth (100ft) 4 - 1.2 (or setpoint) = 2.8. The partial pressure remains the same at that depth as long is the setpoint is steady. Adding fresh diluent due to mask clearing, rise in water column, whatever will not increase nitrogen absorbsion. It is a factor of PPN2 and time.

 

[JeffG]

Let me know if you have any contrary information.

There is that pesky issue known as partial pressure.

 

[catalina_mike]

OK so I'm possibly the only bozo on the bus. Where does the nitrogen go in the loop that is obsorbed by loading? At whatever pressure atm's if your tissue is loading it is comming from somewhere. And if it is comming from the nitrogrgen from the loop the nitrogen in the loop is decreasing. The old you dont get something for nothing. It is a finite amount unless you add more? Maybe I'm the only idiot that thinks about it in this way, but if it is loading in the tissue it came from somewhere and you dont get something for nothing. Most times.....

 

[Mr.X]

OK so I'm possibly the only bozo on the bus. Where does the nitrogen go in the loop that is obsorbed by loading? At whatever pressure atm's if your tissue is loading it is comming from somewhere. And if it is comming from the nitrogrgen from the loop the nitrogen in the loop is decreasing. The old you dont get something for nothing. It is a finite amount unless you add more? Maybe I'm the only idiot that thinks about it in this way, but if it is loading in the tissue it came from somewhere and you dont get something for nothing. Most times.....

I do see your perspective. There are several variables at work here. As mentioned, time & depth are biggies. There are others like tissue/blood perfusion rates & solubility of a particular gas in different people. If anything, we all know that decompression science is anything but exact and that people are quite different in their reaction to inert gases and oxygen.

Barring these variables, the body can load up only so much nitrogen dependent on time, depth etc. If you are using air dil. and going down you will invariably need to add some dil. to the loop as you descend down + make up for minor losses of loop volume due to minor ingasssing of tissues etc. You could certainly make up for individual inert gas losses in the loop with something like oxygen...but then again you would spike your po2 and add gobs to your CNS clock. In other words...there is no bypassing physics or physiology when we actively ruled by partial pressure.

I think your viewpoint really points to the advantage of diving RB's with dil. mix of helium*.

X

* much like the WKPP/GUE diving with a rec. mix of helium

p.s. diving Blue Caverns, or Farnsworth on CCR would absolutely rock. Alas, very little helium on the Island!

 

[bwh6]

OK so I'm possibly the only bozo on the bus. Where does the nitrogen go in the loop that is obsorbed by loading? At whatever pressure atm's if your tissue is loading it is comming from somewhere. And if it is comming from the nitrogrgen from the loop the nitrogen in the loop is decreasing. The old you dont get something for nothing. It is a finite amount unless you add more? Maybe I'm the only idiot that thinks about it in this way, but if it is loading in the tissue it came from somewhere and you dont get something for nothing. Most times.....

The amount of nitrogen entering your tissues is small compared to the loop volume; over the course a dive you will have only absorbed only a small amount of the loop dil.

If we supposed your tissues *do* absorb all the loop dil, then you'd be breathing pure O2 and would have to add more dil anyways to avoid hyperoxia. Note that this doesn't actually happen when you're diving.

Brian

 

[caveseeker7]

... Farnsworth on CCR would absolutely rock.

It does. That's where my profile pic was taken.

 

[Mr.X]

It does. That's where my profile pic was taken.

Caveseeker I hate you!

I did Farnsworth a few times on air, definitely a little narc'd and have always dreamed of getting out there on CCR and helium. Grrrrh.

I had wondered about the avatar because from your Prism shots I guessed it might be kelp at the Casino Excellent!

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