Dead in 7 minutes

[pickens_46929]

Makes some sense I guess - no leaky valve kills you 3x faster basically. At some point though even if you lose consciousness under Scenario 2, you're PO2 will fall below life sustaining levels. It just takes longer as you said.

I was wondering what would happen in the opposite case where you're running on manual, and adding O2 out of habit more than monitoring things.

Could easily see that a diver gets into a set pattern of squirting a little O2 into the loop at a regular interval out of habit, but then the leaky valve also does the same thing and O2 level rises rather than maintains.

If you're flying your rig on manual, forgetting to pay attention to PO2 levels or something else goes wrong with your O2 sensors on auto, I could just as easily see the reverse happening.

 

[Mr.X]

Interesting data Curt. Typically I fly the ECCR manually when I am not doing a huge amount of work. And yes - saves the solenoid / batteries. As I used to dive a KISS - not a whole lot of adaptation on my part with flying manually. Plus, having a HUD all the better. That said - using the leaky valve deep - I have to monitor a tad more. If anything, have to train newbies to be attentive all the time.

 

[wedivebc]

Makes some sense I guess - no leaky valve kills you 3x faster basically. At some point though even if you lose consciousness under Scenario 2, you're PO2 will fall below life sustaining levels. It just takes longer as you said.

I was wondering what would happen in the opposite case where you're running on manual, and adding O2 out of habit more than monitoring things.

Could easily see that a diver gets into a set pattern of squirting a little O2 into the loop at a regular interval out of habit, but then the leaky valve also does the same thing and O2 level rises rather than maintains.

If you're flying your rig on manual, forgetting to pay attention to PO2 levels or something else goes wrong with your O2 sensors on auto, I could just as easily see the reverse happening.

Scenario 2 the diver is more likely to become hyperoxic.. Let's say we have 0.7 l/m flow rate. A moderately working diver metabolizes at a rate of 0.8 l/m eventually he passes out due to hypoxia and assuming the mouthpiece remains intact is still breathing. In his unconsious state his metabolic rate drops to 0.4 l/m now the PO2 climbes eventually reaching a point of hyperoxia and the diver succumbs to oxtox.

 

[Superlyte27]

Except that he'll regain consciousness before that happens.

 

[manni-yunk]

Ever dove a revo to 300'? That leaky valve doesn't work at that depth.

I believe that
the Leaky valve works to 100M if you have a newer unit with RMS. The O2 first stage is now set to 12 bar and therfore Paul's recomendation in hybrid mode for max operating depth is 100M.

 

[Robert Thompson]

So do you think the diver will be able to sustain the work load to drive the PO2 all the way to a severe hypoxic state? I'm going with the workload will probably decrease due to exhaustion, allowing the constant mass flow system to start catching up and at the same time indicating something is wrong. At that point I would expect the diver is checking his PO2 to find out whats up! If you're diving your rig to 300 I would expect you know what you're doing and not expect your rb to just magically supply a breathable gas. There are plenty of people diving well beyond that depth with CMF systems.

 

[wedivebc]

So do you think the diver will be able to sustain the work load to drive the PO2 all the way to a severe hypoxic state? I'm going with the workload will probably decrease due to exhaustion, allowing the constant mass flow system to start catching up and at the same time indicating something is wrong. At that point I would expect the diver is checking his PO2 to find out whats up! If you're diving your rig to 300 I would expect you know what you're doing and not expect your rb to just magically supply a breathable gas. There are plenty of people diving well beyond that depth with CMF systems.

Speaking from personal experience. I once was so focused on swimming to the shot line in surface current that I let my PO2 drop to a frightening level. I did not feel close to passing out but I should have.

 

[voets]

I'm curious how you maintained the minimum loop volume in this test. I've done some testing on my inspiration. Just sat down at 4 meters, closed the O2 tank and watched my handset. I could see the pO2 go down from 0.7 to somewhere around 0.3. But at that point the volume in my counterlungs had decreased so much that I had a hard time breathing.
In the shallows you will notice that either you are sucking in diluent through your ADV all the time, or you have hardly anything left to breath when the O2 is shut off long before you reach hypoxic levels.

Let's say the test was done with 10 liters total volume (own lungs + counterlungs). At the start 7 liters is oxygen. Once you drop down to a pO2 of 0.16 you have lost 5.84 liters of gas in your loop. That would mean your own lungs or the counterlungs are empty, so seems impossible to me to maintain minimal loop volume here.

 

[Robert Thompson]

Yes if you keep minimum loop volume you should notice a lack of volume to breathe before the Oxygen hits a critical level. That's assuming you started with .7 setpoint.

 

[rjack321]

Very interesting and certainly another argument for diving a rEvo. I am curious why you chose a starting PPO2 of 0.7.

why a revo vs any other mCCR or hCCR?