Near miss: O2 valve closed

[jkaterenchuk]

I have these on my O2 and Dil regulator.

http://www.piranhadivemfg.com/item/Mini-Spg-Nitrox-Ready-11795

When I do my dive checklist I can confirm the amount of gas in each tank and then shut off the tank and confirm if any gas is leaking out of the system. Additionally, I can confirm the solenoid is firing by watching the O2 gauge drop in steps.

Prior to getting into the rig I can turn the tanks on and look at the gauge to confirm again the amount of gas and that the system is indeed pressurized. Once in the rig I can press the MAV's while looking at the PO2 on the handset and confirm there operation. I can also test inflation system to confirm. I can then prebreath and watch the PO2 achieve set point and then inject DIL to confirm a PO2 drop and then the solenoid reattaining setpoint. I can then manually inject O2 to achieve as close to 1.0 as possible before entering the water. Once in the water I inject O2 during surface swim and descent to 3 M. The enable DIL ADV (assuming hypoxic mix) and utilze it for the rest of the descent. As you can see there are several point in which gas availability is confirmed and checked.

I decided to remove the normal over the shoulder SPG's after diving the unit for more the 4 years and well over a thousand hours. During all these dives I have recorded on my log sheet which doubles as the checklist (on the back) what my start and end gas was. It stays relatively the same on every dive that is a more less square profile depending upon the total time. I believe in a boom scenerio that I would be able to determine which system (O2 or DIL) is the problem without needing to see the SPG. I then have many different options to utilize to get back to the surface or extend available gas if needed.

I realize others prefer to stick with the SPG available to view during the dive. I wanted to reduce the weight for travel and also the spool leaks that seem relatively common on full size SPG's and after thinking thru the options and risks felt comfortable with this setup. Additionally, I have not had any failures on the 1in SPG's that have been reported by some other divers.

John

 

[Peter L]

Some nice lists but I think the simplest is to consider the unit like any other life support.
Make it operational before you strap it on, power it down after you take it off, don't ever ever ever wear it while powered down or power it down while still in it........

I have had to pull a drowning diver out of 3' of water when he tripped wearing his twinset from the boat to the beach, same problem, life support being worn without being operational.
It took me a minute to get to him and he was very very much in distress by that point.

 

[cmalinowski]

... ie 2 valves 2 gauges 2 mav 2 computers on 2 regs working etc,
before you splash.

Ah, the "twos". I can hear Andrew in my head right now

Chris

 

[Andy Favata]

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.

Looks like you trained with Andrew Driver. He of the 2's. 12 years later 3 different units and I'm still doing them!
For the KISS
2 tanks (valves)
2 gauges
2 inflators
2 mouthpieces
2 gas additions (ADV-MAV)
2 computers
2 min pre-breathe


Andy

 

[MeRodent]

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

For those of us that use proper measurement systems he meant that he uses 25mm size gauges (one inch).

 

[Johnnyh]

I'm posting this as someone with no CCR experience (getting my MOD 1 in Dec on my Sentinel), but who is someone who has a bunch of OC tech experience as well as who works professionally in dive safety.

But isn't it a concern for those who don't dive with gauges that you can't see when in your rig (ie button gauges) that when you do a check like MAV operation and use PPO2 as your verifier, rather than eyeballing your gauge, you run the risk of having only a partially cracked valve? This will work fine at 1 ATA, but with any increase in density (depth), will fail to deliver. Having an 'over the shoulder SPG' would show this issue.

I very nearly bought the farm at 270' on OC during a dive for my job, and it was a perfect example of the snowball effect. Missing a partially cracked valve due to no SPG sounds like an example of the beginning of a snowball.

 

[jkaterenchuk]

In the case of OC you need gas for every breath. On CCR your have plenty of time to continue breathing on the loop if for some reason the O2 reg stopped supplying gas. The O2 is supplied only when needed to maintain the PO2 setpt not with every breath. If you are following normal protocol to monitor you PO2 you would notice the slow dropping of you PO2 at depth and then can problem solve it which would involve reaching back and turning the O2 valve on fully.

John

 

[swadiver]

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

:headbang::spin::scared::bigdump::fart::behead::haha::cussing::censored::uhh::nono::smackbum::cry::ignore::furious:uke:

 

[uwxplorer]

I have seen someone use two wireless pressure gauges on both O2 and Dil tank regs and monitor both on a Galileo wrist-mounted computer (which can also play the role of a standalone deco computer). I was thinking of something like that to replace the chest-strapped, dangling (and occasionally leaky, as pointed previously) pressure gauges.
Any thoughts?

 

[DSix36]

I have seen someone use two wireless pressure gauges on both O2 and Dil tank regs and monitor both on a Galileo wrist-mounted computer (which can also play the role of a standalone deco computer). I was thinking of something like that to replace the chest-strapped, dangling (and occasionally leaky, as pointed previously) pressure gauges.
Any thoughts?

Here are my thoughts on that idea and since it has already been stated earlier in this thread that I am a dive god, it must be right. :banana1:

If you decide to go wireless then you have added a bunch of additional failure points to the simple system. I mean, if you want a Sentinel then go buy one of them rather than ruin such a simple unit. Suddenly you have batteries that can go dead, a wireless connection that has the potential for interruption, and just the failure of electronics. I am not saying that it can not or should not be done, but it does not weigh out in my favor towards the risk/reward factor.

Possibly you could consider shortening the SPG hose to bring it up higher on your chest and thus not dangle. I know this is not a very good option if you are still foolish enough to have dreams on your unit. Those things are like having a damn brick ties to your SPG. If you insist on having dreams installed, then maybe go to the new "P" ones and mount them on the upper rack rather than on the SPG.

 

[Hanssing]

I have seen someone use two wireless pressure gauges on both O2 and Dil tank regs and monitor both on a Galileo wrist-mounted computer (which can also play the role of a standalone deco computer). I was thinking of something like that to replace the chest-strapped, dangling (and occasionally leaky, as pointed previously) pressure gauges.
Any thoughts?

I have one shearwater for 3 cells, one Dream (which I love), installed on the top rack, so it only works as HUD running from 2 cells.
2 button gauges; one for O2 and one for Dil. They get checked when ever I kit up - I never run out of onboard gas, my scrubber/temperature is the limiting factor *.

I have 5 cells to tell me if I run out of O2, besides the audio/tactile feedback when injecting.
I have offboard bailout plumbed in should the 3l. dil run out.

Chest completely "free" - simple as that.


Nicolai

*) Should I have a boom on the onboard, I will just have to act accordingly. Having a gauge telling me I have no O2 left, is the same as feeling theres no flow when pressing the injector.

 

[uwxplorer]

... if you are still foolish enough to have dreams on your unit. Those things are like having a damn brick ties to your SPG. If you insist on having dreams installed, then maybe go to the new "P" ones and mount them on the upper rack rather than on the SPG.

I was convinced (by my instructor) to buy a unit with TWO dreams as a backup (the new ones, not the maracas version Plus they can double-up as defensive or even offensive weapons, I suppose.
That sounded and still sounds like a good advice in case of a SW (or CAN bus) failure.
The wireless option looked seductive enough on the unit I saw it on, but the rEvo is not designed for it (HP port placement, exposure to shock, etc), so I am not too excited about it (not mentioning the cost).
Retractors to stow the two SPG and Dreams to the sides are on my to-try list.

 

[DSix36]

I was convinced (by my instructor) to buy a unit with TWO dreams as a backup (the new ones, not the maracas version Plus they can double-up as defensive or even offensive weapons, I suppose.
That sounded and still sounds like a good advice in case of a SW (or CAN bus) failure.
The wireless option looked seductive enough on the unit I saw it on, but the rEvo is not designed for it (HP port placement, exposure to shock, etc), so I am not too excited about it (not mentioning the cost).
Retractors to stow the two SPG and Dreams to the sides are on my to-try list.

You gotta love salesmen, NOT !!!

Some people will attach a bolt snap to the dream and clip it off to their hip d-ring like a DIR diver does his SPG. In your case it would be both sides.

 

[Ross Isaacs]

Sounds like a near hit to me :bounce:

 

[MeRodent]

You gotta love salesmen, NOT !!!

Some people will attach a bolt snap to the dream and clip it off to their hip d-ring like a DIR diver does his SPG. In your case it would be both sides.

Exactly. Why add complexity?

 

[paulraymaekers]

Some people will attach a bolt snap to the dream and clip it off to their hip d-ring like a DIR diver does his SPG. In your case it would be both sides.

do it already for years, works perfect, no dangling, nicely streamlined, and nothing under the chest strap

and...

I know people that wished they had a second rEvodream the moment they jumped from the platform, the shearwater cable cought on the railing, snapping in two, and showing sparks when hitting the water

with 2 dreams you just run the unit mCCR like any other mCCR unit...

 

[Engelen D]

Retractors to stow the two SPG and Dreams to the sides are on my to-try list.

I stow the dream behind the backplate/wing with a bungee, I can read it from the HUD but can always reach for it if necessary .

 

[Paul Haynes]

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.

Thanks for sharing. We are all prone to errors regardless of experience and implementing processes helps to mitigate this inevitability.

Not to be confused with a CCR preparation assembly and test checklist, one such 'mental' checklist process I teach my students once they have kitted up is CEBID:

C - Cylinders: Open or confirm all are open. Check pressures.

E - Electronics: Switch on or confirm switched on. Check loop PO2 is safe.

B - Breathing: Go onto the loop commence minimum 3 min pre-breathe. Confirm stable PO2 at low set point. Listen for solenoid function.

I - Inflators: Oxygen flush - confirm PO2 rise and individual mV output response. Test function of diluent MAV and ADV. Test BC and drysuit inflation / deflation.

D - Displays: Confirm functionality of primary / secondary / HUD. Confirm dive computer settings / dive timers functioning.

If applied, the post kit up CEBID process will avoid a repeat of the situation you and numerous others have found themselves in after entering the water.

Thanks again. Safe diving.

Paul

 

[uwxplorer]

I stow the dream behind the backplate/wing with a bungee, I can read it from the HUD but can always reach for it if necessary .

Where's the gauge?

 

[uwxplorer]

I know people that wished they had a second rEvodream the moment they jumped from the platform, the shearwater cable cought on the railing, snapping in two, and showing sparks when hitting the water

Sounds like someone should be working on a wireless CAN bus...