Dive with isolator mostly closed?

[MidOH]

I'll find out when I get that training. For now they're indy doubles.

 

[happy-diver]

Do you need training when you increase your valve count from two to three, or permission

Is there any reason not to dive with it open but close to closed for faster shutdown?

None whatsoever and any other answer would be from those without any clue whatsoever

 

[rhwestfall]

Well, apparently I'm clueless...

I run mine (isolator) mostly closed. I also have a vindicator on the isolation valve for visual reference when suiting up. It also is a larger/longer handle I fine easier to use.

On top of that, NOBODY touches my valves. Even on a babysitting cattle boat when using singles (where it seems things get messed with).... If they are adjusted by someone, I'm sitting back down and resetting.... and also having an unpleasant dialogue with someone.

 

[iointerrupt]

No one seems to have mentioned the problem with 'partially closed' valves: they may not behave well.

Your typical high pressure scuba valve if just cracked slightly open, may flow gas at 3000psi (200bar), but then act like a closed valve at 1000psi (70 bar).

You can find numerous stories of people jumping in with partially open valves, and suddenly finding themselves out-of-air while descending.

You'd seemingly be better off diving as BlueTrin suggested: fully closed isolator, equalize periodically. I believe @Akimbo mentioned diving this way.

 

[lostsheep]

It is not unusual for people to turn a thread (valve, tap, nut, bolt) the wrong way when trying to do it from an unfamiliar angle. Such as twisted your arm in a weird way to get to a hard-to-get-to nut, or reaching behind your head to open (err.. close.. err.. hang on..) your isolater.

FWIW I have mine fully open.

That is exactly what I was alluding to and why I included the bit about being familiar with threads. There are those of us that do not turn threads or valves backwards no matter where they are. I could see a 9 to 5 calligrapher getting confused but a machinist is going to get it right.

 

[rob.mwpropane]

I run mine (isolator) mostly closed.

This is what I do. If it needs to be shut down takes way less time. I shut mine down (if I can remember) 1/2 way through a dive so instead of swapping doubles I can whip from say a HP120 and get close to full again (also depends on the dive).

To anyone that wants to see what it takes to equalize the tanks, start with it closed and count how many turns it takes 1/2 way through the dive to equalize. You'll hear it open and then you'll know what to start with open. I add another 1/2 turn for good measure. Or do whatever you're comfortable with.

I could see a 9 to 5 calligrapher getting confused but a machinist is going to get it right.

I am a gasfitter by trade, couldn't agree more. I tell the new guys just treat 95% of the fittings we do as you would a soda bottle cap. Righty tighty, lefty loosey... they still don't get it. Struggle all day with pipe, but never opening a bottle, go figure.

I tell them for the reverse threads stuff you're ******!

 

[Akimbo]

You'd seemingly be better off diving as BlueTrin suggested: fully closed isolator, equalize periodically. I believe @Akimbo mentioned diving this way.

I learned the technique called progressive equalization from ex-British Navy divers in the 1970s. It was developed because they often operated in in zero visibility so could not read an SPG even if they had one. My doubles for local diving have a protector so they can be worn valve-down.

Equalizing can be used to trigger events in your dive profile, like head back toward the boat or leave bottom.

 

[Bazzathemammoth]

You do realise that's old school thinking for ancient valves, which is not a concern with any equipment from this century?

This is from way back… in 2018

Tank Valve Stuck Open

Went diving last weekend. Woohoo! Surfaced with ~500 psi in my rented AL80 after my first dive and couldn't get the tank valve to budge. What would you do if this happened to you?

scubaboard.com

This is from DAN:

“valves are now less prone to leaking or sticking open. While the quarter-turn-back practice is still present in other industries to prevent valve damage and ensure that valves do not stick open, the dive industry is moving away from this practice because people unfortunately keep getting injured.”

Apparently, it’s no longer recommended not because it is no longer needed but rather folks are getting confused as to what is open and what is closed. Less prone indicates that it still happens.

I did my intro to tech course the other day, and thought I would do the traditionally recommended thing of fully opening my tank valves. My left post ended up jammed open and I couldn’t close it. That’s the last time I ever dive a fully open valve on my Twinset.

Also we were taught that the manifold isolation valve position was up to personal preference, either fully open, then back a 1/4 turn or partially open. The argument against partially open from the instructor was that some people get confused about which way to turn it. I decided to run with mine partially open. I’m never going to turn that valve the wrong way, and I’d like to save gas as quick as possible if needed.

 

[aquaregia]

Failures requiring an isolator shutdown are very rare, and the additional time saved by having them halfway closed will be minimal compared to the time needed to make the decision to close the isolator. However, if a shutdown is needed, under stress you may turn them the wrong way and open the isolator fully instead of closing it. I leave the isolator fully open, but keeping the isolator fully closed and using progressive isolation would also prevent the potential human factors error.

Speaking of human factors errors, this is also why I don't turn my valves a quarter turn back, even though I have had (modern and maintained) valves get jammed closed. Valves jammed open can be inconvenient but require several associated failures to be life threatening, whereas a quarter-open valve can be deadly on its own.

 

[rob.mwpropane]

Failures requiring an isolator shutdown are very rare, and the additional time saved by having them halfway closed will be minimal compared to the time needed to make the decision to close the isolator. However, if a shutdown is needed, under stress you may turn them the wrong way and open the isolator fully instead of closing it. I leave the isolator fully open, but keeping the isolator fully closed and using progressive isolation would also prevent the potential human factors error.

Speaking of human factors errors, this is also why I don't turn my valves a quarter turn back, even though I have had (modern and maintained) valves get jammed closed. Valves jammed open can be inconvenient but require several associated failures to be life threatening, whereas a quarter-open valve can be deadly on its own.

I don't think it's a matter of do it this way or that way. Pick a way that makes sense to you and practice it. 1/2 way open, closed, all the way open... doesn't matter as long as you practice. It should be so engrained it's like opening a soda bottle under duress... I don't think anyone would get that wrong, even with a gun to their head.

I have gotten into the habit of doing valve drills when my hands start to get cold. It keeps things fresh and moves some air through the suit and warms me up a little bit, and that's on every dive.