Manifold open or closed?

[DEEPLOU]

Matt, here's what I was addressing...

Quote:
Originally Posted by DEEPLOU
my experience was the other way around, (and yes I screwed up in not doing pre dive check of it) .
The ace who filled my tanks closed the isolator after he filled them. When I was at the end of my dive on the hang, I looked and "Wow" the spg still read 3000! At first I thought the needle was stuck, but then I reached back and opened the isolator (it only took a second) and as soon as it opened I heard a "woosh" and the gage dropped to abt 1600.


To which Soggy replied...

Quote:
Originally Posted by Soggy
Ouch...that could've led to a *really* bad situation as you now have a completely unknown FO2....If I discovered my isolator was closed during the dive, I would *leave* it that way and abort abort abort. At least I know that what I analyzed is what I am probably breathing. I might even go 'OOA' and share gas with my buddy who at least now has a known breathing supply.


To which SeanQ asked...

Quote:
Originally Posted by SeanQ
How does the F02 change when this happens?

Admittedly that was a situation I should have checked before dive. (no one is perfect)
As the situation I described was caught @20ft deco stop, I had already just switched to deco gas. What was in the tanks (in this particular incident) after opening the isolator didn't make any difference (unless there was problem w/deco gas) as the back gas wasn't being used any longer.

As to the FO2 if it was different mix in each tank, it probalby would not be that significant. If one tank that was full had 32% and the one breathed had 30%, the end mix would be between 32 and 30.
If such a problem were discovered during a dive it would be the time to abort.
Remember Oxtox involves not just the PPO2 but the duration of the dose.

 

[decodiver637]

This is my second post. I just wanted to thank you guys for a good laugh. This thread was great. I know i check my manifold before they get filled after they get filled and before i dive. I would have though every one did this.

 

[Daryl Morse]

Who does it happen to? Do you personally know of anyone?

I believe one of the fatalities of Doria divers off the Seeker was at least partially attributed to a closed isolation valve. It was the Italian guy (Vince) who had OOA plus other problems.

Not that this is an argument either for or against diving with an isolation valve closed. The apparent problem was that he thought the valve was open, as per his usual procedure, but it wasn't and he was to toxed (or whatever) to realize what was wrong.

If someone has a better recollection of the circumstances, I will stand corrected.

 

[subcookie]

I dive with mine close.I dive in cold water and my dry suit does nt allow me to move as freely as i would like, so I decide to dive with mine close with 2 spgs. If you use the rule of 1/3 you should never get into problem.

 

[Derek S]

I dive with mine close.I dive in cold water and my dry suit does nt allow me to move as freely as i would like, so I decide to dive with mine close with 2 spgs. If you use the rule of 1/3 you should never get into problem.

Then your suit is either too big or too small.