Half Turned Valve

[TheRedHead]

I boat diving a few days ago in Cozumel and had my primary regulator shut down at about 60 feet on descent. I had set up my gear and turned on both my valves (single tank with H-valve) and double checked everything before getting into my harness. I never turn the valve back half a twist and always dive with my valves fully open.

When my primary regulator failed, I immediately went to my bungeed secondary, which to my great relief was fully open. I then signaled my team that my right post was off and my buddy opened my valve and we proceeded with the dive.

I can only assume that one of the DM's shut down my right post valve and twisted it open a half turn while I was making my way to the dive platform. I noticed nothing wrong when I began my descent as the reg was delivering air.

The practice of turning a valve a half twist is dangerous as it could have turned out very badly. Since I had my left valve open and was also carrying a 40 cu ft. stage of EAN36, I knew I wasn't in danger, but it would have been a different story with a single tank.

My lesson learned is that I'm going to check my valves on the surface before descending from now on. Secondly, I'm going to make sure all the DMs understand that they are NOT to touch my valves on the way to the dive platform. I will also continue to stay within an arm's reach of my team members on descent.

 

[do it easy]

Glad to hear that you made it back.

I'm not too picky about crew touching my valves- I can understand their concern, I breathe off the regs before I jump in and then check the valves after after I splash in. I just wish they would remind me to check my HID batteries...

 

[Thalassamania]

The practice of turning a valve a half twist is dangerous as it could have turned out very badly. Since I had my left valve open and was also carrying a 40 cu ft. stage of EAN36, I knew I wasn't in danger, but it would have been a different story with a single tank.

My lesson learned is that I'm going to check my valves on the surface before descending from now on. Secondly, I'm going to make sure all the DMs understand that they are NOT to touch my valves on the way to the dive platform. I will also continue to stay within an arm's reach of my team members on descent.

Glad it came out OK. The danger is not from turning the valve back half a turn, most of us old timers will never get out of that, now unnecessary, habit. The danger comes from permitting semi-housebroken chimpanzees that suffer from confustion of lateral dominance to touch any of your gear. The first thing that I tell the DMs on a boat is, "Please, do not touch any of my equipment, but feel free to use words, e.g., is your tank valve open?"

You can detect this problem with a quick glance at your spg, it will drop with each breath and then pop back up when the vavle is just cracked open (try it yourself and see).

 

[Jcsgt]

This is precisely why I like to handle my own gear. If I see a crewmember, albeit with good intentions, trying to set up my gear, I go right along behind him and make my own adjustments.

 

[TheRedHead]

This is precisely why I like to handle my own gear. If I see a crewmember, albeit with good intentions, trying to set up my gear, I go right along behind him and make my own adjustments.

I did set up my own gear and breathed my regs while sitting on the bench. In fact, my buddy and I were taking an IANTD class and we had a special section on the bench with our instructor. I stood up and one of the DMs clipped my stage bottle to my left side and I proceeded to make my way to the dive platform with him behind me. I'm sure that's when it happened. :shakehead

 

[markfm]

I breathe my regs immediately (as in just before the stride or roll) before entry -- that's why.

 

[Sasquatch]

Was his name Murphy by any chance?

Glad it wasn't a huge deal. Right, if diving just a single and this happened at depth there might have been some gray hair produced.

 

[dannobee]

I'm with T on this one. Just before you do the giant stride, give the inflator a few bursts and a couple of breaths on the reg while watching the SPG needle. If it drops, the valve isn't open all the way. Get in the habit of doing this every time and you won't ever worry about valves being closed or partially open. Set up your gear in the garage and try it just to see what it looks like.

 

[do it easy]

I'm of the belief that there is an "unlucky" valve setting where it will deliver sufficient gas at the surface to pass the SPG needle bounce test, but will fail at depth, although that depth might be deeper than 60'

I'm also of the belief that the best way to ensure that the valve is fully open is to reach back and physically check it. Yes, the looking at the SPG is a good cross check that is easy to do since we should be checking our pressure anyway, but actually manipulating the valve just before I descend gives me much more peace of mind that the valve is indeed fully open.

 

[TheRedHead]

I'm with T on this one. Just before you do the giant stride, give the inflator a few bursts and a couple of breaths on the reg while watching the SPG needle. If it drops, the valve isn't open all the way. Get in the habit of doing this every time and you won't ever worry about valves being closed or partially open. Set up your gear in the garage and try it just to see what it looks like.

It was a live boat drop into a current and had a stage bottle clipped in front of my SPG. I had shot air into my wing and my Apeks breathed fine on the surface. The reg delivered air normally until about 60 feet. I always watch the SPG and breathe my regs. The SPG was connected to my left post which was open. I think perhaps using a high performance regulator masked the effect of the almost closed valve.

I maintain that cranking the valve a half turn back is a very bad practice. If the DM handn't touched my valve, this incident would not have happened.