Proper valve drill sequence

[Divor]

The way I'm doing it now:

Shut isolator
Shut right valve
Switch to octopus
Open right valve
Switch to primary
Shut left valve
Open left valve
Open isolator

I've been taught to isolate first, and I like the reasoning behind it. I've seen lots of videos on Youtube that shut the right valve first. What's better and why?

 

[Blackwood]

I go right to left, but it's a drill. It doesn't really matter which order you do it in.

The valve drill exists to promote familiarity with your valves, which knob does what, etc..

 

[LiteHedded]

because that regulator is the one most likely to fail. shutting that isolator first is just wasting gas IMO.

 

[Blackwood]

because that regulator is the one most likely to fail. shutting that isolator first is just wasting gas IMO.

Agreed, though I guess I can maybe see shutting the isolator first IRL if you have no clue what is failing (rather than hedging your bets with the odds on favorite). If the time it takes to shut the isolator first matters, then so does the time it takes to shut the right post AND re-open it.

For the purposes of a valve drill, though, I don't think it matters.

 

[elan]

The way I'm doing it now:

Shut isolator
Shut right valve
Switch to octopus
Open right valve
Switch to primary
Shut left valve
Open left valve
Open isolator

I've been taught to isolate first, and I like the reasoning behind it. I've seen lots of videos on Youtube that shut the right valve first. What's better and why?

No matter which sequence you do it do a quick check at the end to make sure all valves are open.

 

[LiteHedded]

Agreed, though I guess I can maybe see shutting the isolator first IRL if you have no clue what is failing (rather than hedging your bets with the odds on favorite). If the time it takes to shut the isolator first matters, then so does the time it takes to shut the right post AND re-open it.

For the purposes of a valve drill, though, I don't think it matters.

agreed. in reality I'm going to listen to where it's coming from and shut that post down first. i will have already signaled my buddy and he will be on his way to assist me.
the drill is more about muscle memory than anything else.

 

[Trace Malinowski]

The way I'm doing it now:

Shut isolator
Shut right valve
Switch to octopus
Open right valve
Switch to primary
Shut left valve
Open left valve
Open isolator

I've been taught to isolate first, and I like the reasoning behind it. I've seen lots of videos on Youtube that shut the right valve first. What's better and why?

Going for the right post first in a valve drill is simply one way of doing it. Some advocate it because it is simply a solid right to left systematic approach to a drill. Others advocate it because they claim that the right post will be more likely to fail since an impact with an overhead while moving forward could fracture the right post by opening it beyond the natural stopping point of the knob, whereas your left post would be rolling toward the off or closed position.

Of the three possible knobs to start a valve drill, the left post is theoretically the least preferred because it has lower risk of failure and cannot isolate the gas supply. In real-life, I've had more left post problems than right post problems.

I do valve drills going for the right post first.

1. "Attention!" Get a lifeguard
2. Test back-up regulator
3. Shut down right post
4. Switch to back-up
5. Open right post
6. Test primary then return to primary
7. Isolator closed then open
8. Shut down left post and purge back-up
9. Left post open
10. Test back-up
11. Perform a flow check: right post open, isolator open, left post open, check SPG
12. Signal lifeguard, "Okay"

Some people also signal "Attention!" while turning each knob. This looks silly, but reinforces the ability to signal your team members while being able to begin dealing with a failure simultaneously.

In a real situation, closing the offending side is your first move. Those who opt to go for the right side when they can't tell if that is the problem side are going to take a chance that they are correct. If they are wrong, the isolator is their next move with a high probability that they now know where the problem lies. Those who choose to isolate first are taking the gamble that doing so will preserve gas and that their next move will correct the problem.

Either way works and makes sense. The principle of primacy is that what we learn first we retain. I learned right post first, so I do my drills that way.

No real issues either way. How your team or buddy likes to do drills may result in changing up from time to time.

 

[TSandM]

I've heard passionate arguments for doing the drill various ways. I don't think it matters very much in which order you shut posts. But I do like returning to the primary reg before shutting, and then purging, the left post, because that way, I think you are less likely to forget that you have to purge the left post to make the bubbles stop, should you have a left post failure to deal with.

There are also some good arguments on both sides of the "isolator or right post first" question. My plan is to listen and try to identify the side (which is pretty easy with an airgun and no hood, but might be far more difficult in other circumstances, I suppose) and if I can't tell at all where the leak is coming from, shut the right post and isolator simultaneously, if I can.

 

[rjack321]

Shutting the isolator first only actually saves gas if you have a burst disk, manifold, or neck oring fail. If a regulator fails (more likely) shutting the isolator actually wastes gas. Shutting the isolator also doesn't give you any feedback on what's wrong. You can only get feedback from shutting off the offending reg or in the case of a manifold burst disk, neck oring, failure, from a buddy.

If you are solo diving or have a solo mentality, by all means go for the isolator first since you can't afford the low probability but high risk burst disk/neck ring/manifold failure.

If you are diving with proper buddies then go for the apparent offending reg since there's a small chance you'll misID the issue and continue to lose gas from a manifold/neck oring/burst disk. The high probability failure is a better bet with your buddy capable of covering the low probability mistake (burst disk et al).

 

[Sas]

I have been taught

- close right valve and breath down
- switch to backup; clip off right reg
- open right valve
- switch to right reg
- close isolator
- open isolator
- close left valve
- check by purging the occy
- open left valve
- flow check

In the event of a failure:

- signal team
- listen right and left
- shutdown offending post breathe/purge + switch
- if bubbles don't stop, isolate

I was also taught to turn off right post if I can't identify the issue at first, as it is the most likely to have failed.

So yea, that's pretty much what I have done in practice - failures I have had have been easy to identify. If I was solo diving, I would probably isolate first if I could not tell where the leak was but otherwise I will have my buddy assisting me and would shut down whichever post I thought was leaking first.