Near miss: O2 valve closed

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Well, my first post here is a near miss.

I set up on the back of my car, everything ready to go after a good pre-breathe. I then walk past the car to grab my mask and hear some pressure leaking from somewhere close. To check it was not the CCR I went back and closed both valves while noting the pressure of the gauges. After grabbing my mask I investigated where the noise was coming from and figured it was my buddies tank. After fixing his kit and a bit of time passed, I forgot that I had both valves closed, but interestingly checked the gauges (which were both fine).

With the unit on my back I made my way to the water (the entry there is a bit tricky). I put my mouthpiece in just before entering, went into the water, rigged the bailout and put fins on. Yes, all this with both valves closed. The HUD did not yet go off and no alarm yet (so ppO2 was likely still safe).

As I felt a bit of restriction and had my ADV off, so I tried to manually add O2 and nothing happened (pipes likely drained at this stage). Turned the O2 on rather quickly and checked ppO2 which was at setpoint by this time.

The importance of the near miss: my integrated bail out would have failed due to the closed diluent valve as well as the BCD inflator. Clearly more diligence required before water entry from now on - I really need to check both valves and monitor ppo2 and gauges closely before entry into the water.
I find the water entry a critical moment, not really set up and struggling to get a lots of equipment going quickly. In the other recent O2 valve thread, the suggestion of going to 1.0 before entry seems a good hint, this ensures the inflator works and gives more time if things go wrong or slow. O2 is cheap.

Hope this helps.
 
Welcome to CCRX and thank you for your timely post! We all can't be reminded often enough about this kind of thing so thank you for sharing your experience with us!
 
Even though it was your first post, kudos for having the balls to fess up about a mistake.

This type of thing has always caused me to ponder the possible ways to overcome the issue. I have developed a pattern or protocol that has since turned into muscle memory and has served me very well.

I have this very simple mantra:

When the DSV is placed in my mouth, I reach back and verify that both valves are turned on.
When the DSV is removed form my mouth, I reach back and turn off the O2 (only because I have a hybrid with a leaky valve).

Personally, I think the training agencies need to teach this same mantra. But then again it might just be that I am biased to my approach.
 
First, the thread title is misleading, since BOTH O2 and dip tank valves were turned off.
Then, I have recently witnessed the same exact problem on another diver, who realized it at ~20 ft (ADV inactive). The diver bailed out, signalled to me he had a problem, solved it and off we went.
Post dive, it turned out the guy had not gone through his checklist carefully. Now, I do not blame him, although as new divers we could have screwed up in case the situation had been a bit more edgy.
The OP may have gone through his checklist thoroughly, but then he changed something. How can these scenarios be handled effectively? You can't always go over your full checklist again, but maybe "cancel out" any post-pre dive action immediately? The problem is, since these post-pre dive actions are not usual ones, there is no muscle memory to rely on...
What are experienced divers recommendations?
 
A few years ago I did a poll on a forum for near misses, 80% involved O2, either off, low pressure, not connected etc.

The simplist parts are those most often missed- even the smartest rebreathers can't stop the user turning a tank valve off :-)

Good first post BTW.
 
paulraymaekers said:
Why would you close your tanks to investigate something, when you're ready to jump...? I think there is no reason to do this! Just leave them open.
Click to expand...

I did my assembly checklist at home in the evening before. Then drove to the dive site in the morning. My pre-dive checklist does not include a test for a drop in pressure. Thus my suspicion was that something came loose during the drive or setup for the dive and thus the noise. I responded a bit like a boom drill basically, close it off, check and then back on once verified - just that I missed the last bit.

It could be argued to include the pressure drop test in the pre-dive list, but where do you stop then - you may end up with a pre-dive list that mirrors the assembly +
 
Great first post. Thanks for the honesty.

On OC we were taught to take a couple of breaths while looking at our SPG. That finds the issue of the closed valve very quickly. I use the same approach during my prebreathe, even if it for only a few seconds. Make sure the ADV fires, make sure the solenoid fires (on eCCR), and make sure both MAVs work. Then look at both gauges. This last simple step should find the problem. But I have studied a lot of people during their prebreathe and find very few who ever look at their gauges. And there are some who think onboard gauges are unnecessary.

This is just an extension of what we all learned in our basic OW classes. Why isn't it just as important now?
 
Pressure drop test upon flushing either diluent or O2 is part of the rEvo pre-dive checklist. It makes a lot of sense in hindsight, doesn't it? It is also quite a short list.
My question is how to best handle "last second improvisations" when you are in a potentially stressful environment...and of the forgetful kind...
I guess don't improvise (Paul) or be focused at all times?
 
DSix36 said:
Even though it was your first post, kudos for having the balls to fess up about a mistake.

This type of thing has always caused me to ponder the possible ways to overcome the issue. I have developed a pattern or protocol that has since turned into muscle memory and has served me very well.

I have this very simple mantra:

When the DSV is placed in my mouth, I reach back and verify that both valves are turned on.
When the DSV is removed form my mouth, I reach back and turn off the O2 (only because I have a hybrid with a leaky valve).

Personally, I think the training agencies need to teach this same mantra. But then again it might just be that I am biased to my approach.
Click to expand...

To the OP, you will soon find that the advice of DSix36 is often the best you will find as he has no fear about being embarrassed and is happy to speak his mind. (such as it is :-) )

More to the point, I am with Don on the jump mantra. At that point you are well past check lists and a simple way to cover just a few critical points will serve you well.

Peter
 
For most units, there are 2 checklists:
1. Build checklist
2. Pre-dive/pre-flight checklist - this is the one that almost always mandates a check to ensure O2 and Dil are turned on prior to entering the water.
 
Randy Thornton said:
For most units, there are 2 checklists:
1. Build checklist
2. Pre-dive/pre-flight checklist - this is the one that almost always mandates a check to ensure O2 and Dil are turned on prior to entering the water.
Click to expand...
I Use both full lists and would like to know whats on your jumplist ? , ie 2 valves 2 gauges 2 mav 2 computers on 2 regs working etc,
before you splash.
 
kwinter said:
I think I should report this as spam. Obviously the work of a bot, since no human would ever utter such a phrase.
Click to expand...

Your just jealous of Don the diving God. He is most certainly one of the most quoted contributors on the various diving forums. He is apparently fearless, but at the same time humble. Although blunt, he has very good manners.

Best of all he has provoked great mirth. It is true that the humour is sometimes more intentional than others, but a laugh is a laugh.

You have much to learn Ken. :nod:


Peter
 
PeterN said:
Your just jealous of Don the diving God. He is most certainly one of the most quoted contributors on the various diving forums. He is apparently fearless, but at the same time humble. Although blunt, he has very good manners.

Best of all he has provoked great mirth. It is true that the humour is sometimes more intentional than others, but a laugh is a laugh.

You have much to learn Ken. :nod:


Peter
Click to expand...

I just lost my dinner. Thanks for helping my bulimia diet.
 
PeterN said:
Your just jealous of Don the diving God. He is most certainly one of the most quoted contributors on the various diving forums. He is apparently fearless, but at the same time humble. Although blunt, he has very good manners.

Best of all he has provoked great mirth. It is true that the humour is sometimes more intentional than others, but a laugh is a laugh.

You have much to learn Ken. :nod:


Peter
Click to expand...

What Don are you talking about? Because that word "humble" leaves out the Don I know.


Sent from my iPad using Tapatalk HD
 
markdol1 said:
I Use both full lists and would like to know whats on your jumplist ? , ie 2 valves 2 gauges 2 mav 2 computers on 2 regs working etc,
before you splash.
Click to expand...

Turn cylinders on, check manual add valves, verify pressures
Verify Hansets/HUD
Prebreathe, verify set point, check PO2
Wing, drysuit function
Bailout function/pressure
Fill loop w/O2

If prebreath has already been done, then I at least verify manual adds, verify pressures, check wing/drysuit inflation, check bailout, check set point, check PO2, fill loop with O2.
 
kwinter said:
Great first post. Thanks for the honesty.

On OC we were taught to take a couple of breaths while looking at our SPG. That finds the issue of the closed valve very quickly. I use the same approach during my prebreathe, even if it for only a few seconds. Make sure the ADV fires, make sure the solenoid fires (on eCCR), and make sure both MAVs work. Then look at both gauges. This last simple step should find the problem. But I have studied a lot of people during their prebreathe and find very few who ever look at their gauges. And there are some who think onboard gauges are unnecessary.

This is just an extension of what we all learned in our basic OW classes. Why isn't it just as important now?
Click to expand...

Ken

For those that do not feel the need for large SPG's visable by the diver during the dive. In this case there is no need to LOOK at the gauges to verify. Sure it's fine to do but If you have pre-breathed the unit. tested the MAV's a couple of times, checked the solenoid controls the unit to set point and manually brought your ppO2 up to close to 1.0 as part of you pre-jump checks it would be evident if something is turned off as the gas volume remaining in the hoses would have been long depleted. I now have 1 in gauges on my 1st stages so they get checked at two different times. Once when doing my pre-dive check list (looking to see if there are any leaks in the gas system) and once prior to getting into the unit to dive.

John

John
 
jkaterenchuk said:
Ken

For those that do not feel the need for large SPG's visable by the diver during the dive. In this case there is no need to LOOK at the gauges to verify. Sure it's fine to do but If you have pre-breathed the unit. tested the MAV's a couple of times, checked the solenoid controls the unit to set point and manually brought your ppO2 up to close to 1.0 as part of you pre-jump checks it would be evident if something is turned off as the gas volume remaining in the hoses would have been long depleted. I now have 1 in gauges on my 1st stages so they get checked at two different times. Once when doing my pre-dive check list (looking to see if there are any leaks in the gas system) and once prior to getting into the unit to dive.

John

John
Click to expand...

Point taken. There's a whole separate thread about using SPGs vs not having any. You and JonT are welcome to skip them or use button gauges. I prefer to have regular gauges tucked away somewhere as long as they don't get in the way. Live and let live.
 
jkaterenchuk said:
Ken

I now have 1 in gauges on my 1st stages ......

John

John
Click to expand...


John, I think you miss typed. At least I don't understand what this means. For what it is worth, I tried button gauges, no gauges and I am now back to spgs on hoses as they are much more durable than button gauges and it is often nice to just know what is in any given tank.

Peter
 
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