Valve Drill Logistics

[do it easy]

I've been considering the valve drill lately and looking for ways to improve it.

First off, it seems as if most people learn the valve drill like this:
right post off
right post on
isolator off
isolator on
left post off
left post on

I left out the bits about purging, signaling, clipping.

As far as I can tell, this has the advantage of working all the valves systematically from right to left and re-opening each valve immediately after it is closed and voided. I think the biggest drawback is in the case of a burst disk or tank o-ring failure, then the isolator is re-opened before a left post failure is ruled out.

I think of the valve drill as a procedure of last resort in the event that you can't immediately identify and stop a leak. It needs to be systematic so that the unidentifiable failure can be found and managed.

To that end, I came up with this version:
right post off
isolator off
right post on
left post off
left post on
isolator on

Stop the drill when the bubbles stop. If they don't stop after turning the left post off and purging/breathing it down, then skip the last step, look at the SPG, and have a buddy verify that you have an unstoppable failure.

This version has the advantage of isolating the tanks earlier and leaving them isolated until a reg failure is ruled out by closing each post to see if the bubbles stop. I think there are other ways to do this, but I wanted to only manipulate one valve at a time.

I'm assuming that the worst case scenario is diving in an overhead, arriving at turn pressure, and having a manifold failure that is not readily identified.

OK, the pool is open for discussion!

 

[rongoodman]

As it was explained to me, the valve drill is an exercise in reaching and manipulating the valves. It's not meant to be a troubleshooting procedure or a response to a failure.

 

[texdiveguy]

As it was explained to me, the valve drill is an exercise in reaching and manipulating the valves. It's not meant to be a troubleshooting procedure or a response to a failure.

Actually you are correct for the most part. Though if ness. the 'drill' can be used to locate the area at issue in the event of a gas loose failure.

For me....I persl. always shut down the 'isolator' as my first move, its quick and easy and assures that the valve/tank at issue will not continue to draw gas from the unaffected valve/tank...then the process of determining which side is at issue begins, and then taking the appropriate actions to correct the failure and continued loose of gas. The last step is re-opening the isolator after the problem is resolved.

 

[willardj]

I like to shut the isolator down first as well. With a quick glance at pressure gauge. Then shut done the problem. If the problem stops Reopen the isoator. If problem continues. The isolater is already shut to keep it under control.

 

[Dirkadiver]

I agree w/ the last two posts. If the failure point is unknown, shut the isolator down first, then process of elimination w/ the posts.

On the other hand, in the OP, he's shutting down right post, then the isolator.(Not turning right post back on before turning isolator off). I think in that sequence, assuming your halfway decent @ valve drills, it wouldn't make much difference if you shut down isolator or right post first as long as both are shut down immediately.

 

[Divin'Papaw]

I'm just learning this stuff, but doesn't this get at the difference between a valve drill and a 9 failures analysis? A valve drill is simple, easy to remember, methodical and is all about making sure the valves are reachable and can be shut down/turned back on by the diver themselves. In the event that bubbles are encountered, that would lead to the initiation of a 9 failures analysis. From the flowchart I've seen, the isolator is shut down pretty early in that process to prevent complete loss of gas supply.

Do I at least have that close to correct?

 

[Flightlead]

First off, it seems as if most people learn the valve drill like this:
right post off
right post on
isolator off
isolator on
left post off
left post on

...

To that end, I came up with this version:
right post off
isolator off
right post on
left post off
left post on
isolator on
...
This version has the advantage of isolating the tanks earlier and leaving them isolated until a reg failure is ruled out by closing each post to see if the bubbles stop.

I have been instructed that the first thing is to close the isolator. That way in a worst case scenario (single failure) you maximize your retained gas at half of what you had.

isolator off
right post off
right post on
left post off
left post on
isolator on

 

[Rick Inman]

I'm just learning this stuff, but doesn't this get at the difference between a valve drill and a 9 failures analysis? A valve drill is simple, easy to remember, methodical and is all about making sure the valves are reachable and can be shut down/turned back on by the diver themselves. In the event that bubbles are encountered, that would lead to the initiation of a 9 failures analysis. From the flowchart I've seen, the isolator is shut down pretty early in that process to prevent complete loss of gas supply.

Do I at least have that close to correct?

In the 9 failures flow you have right/left shutdown first, then listen for bubbles, then isolator.

 

[texdiveguy]

In the 9 failures flow you have right/left shutdown first, then listen for bubbles, then isolator.

The 9 Failures flow does build in that 'flaw' of wasted time while gas is escaping.....always shut down the isolator first thing.

 

[lowridersvt]

The way you are trained to do vavle drill is difrent from agency to agency and from instructor to instructor . I was trained to shut down the isolator first in the mind set to save half your gas .But valve drill are far from what you will see in the real world emergency usaly the first thing to go is your main breathing reg . So Starting with your right post on a vavle drill can be considered a good idea . I still believe in shutting down the isolator first if you dont know were the bubbles are comming from then get your teammate to check you for bubbles Then call the dive wile your team mate monitors you for any issues .

The rule of thumb if you can do the vavle drill in 30-60 sec your doing good no matter what way you do it