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This may be a stupid question so go easy on me,
I have often wondered what procedure to follow if I had a leak from my manifold at depth , say I banged it in a wreck or cave for example.
I recently had one blow on the surface, and it made me think!, obviously the dive would be aborted, but things are not always that easy in over head enviroments and say Id lost contact with my buddy. Is there any sort of drill to follow ?
My theory on this is that it would only crack on one side of the isolator which if closed would give me air from one post, it seems to make sense but Im unsure
 

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You're right: A manifold failure would most likely occur on either side of the isolator, therefore you'd be able to retain half your gas.

I believe I'm right in saying that there has never been a single occurence of catastrophic isolator failure, i.e. a manifold failure that unavoidably lost all gas.

However, it could happen in theory, and it's not hard to see why close-confine divers use independants.
 

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A catastrophic manifold failure is extremely rare.  I'd be interested to hear what happened to your manifold.

In the event of *any* kind of first stage/valve/manifold failure you should first shut down the valve on the side that you "think" is giving the problem and switch second stages accordingly.  If that doesn't fix it, shut the isolator (I think this is actually contrary to what some agencies teach). Shutting the isolator preserves at least half your remaining gas.

If you are skilled and proficient in shutting down valves, doing it this way will always preserve the max amount of back gas.
 

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I can see what your saying there Bob, but I have been trained to shut the isolator first, but I am pretty wet behind the ears and always open to suggestions.
Maybe when I finally get proficient at shutdowns in a drysuit (Im fine in a wet suit!) Ill definatly give it a go, at the moment I would probably shut the wrong post lossing more air, but I suppose using a mirror would work well. If doing it this way, what is the point of the isolator?
Shit its Saturday, Im off to the Pub!


(Edited by Paul Hinchliffe at 1:22 pm on Feb. 23, 2003)
 

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Hello all,
Are shutdowns nesessay when not diving in cold water? I have been diving since 1993, me and my buddies never had a single free flow, only bust o-rings from whom still use A-clamps. Also if one is diving with independent twins what the use to shut down, here water temp. min is 13'c, so if we have a free flow is more a mechanical problem then ice forming.If one is using rule of thirds and have a problem just call the dive and head back or up until with deco MOD, what you think? How often you have a free flow during your diving, normally I speak with my Canadian friend who normally in a dive makes more shutdowns than he checks the gauge
 

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I'm with Paul H on this one...close the iso valve first and your at least 50% to getting it sorted.  closing one pillar first then the iso if you are wrong??? Seems like a non system to me unless you are diving very thin gloves or can see (mirror) where the problem is.  More steps in the equation whilst loosing gas from both sides...in my opinion, the quicke the isop is shut, the quicker you have a reiable gas source to use whilst the problem is addressed.

 

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<font color='#000F22'>I agree

Isolate first then try to locate problem. However I use a slob knob so isolation takes less than 3 seconds. If you are using central isolation in the conventional way it might be quicker to isolate the side valve first as it is IMHO more dificult to reach the center knob.

Lets face it if you have a free flow it is most likley the reg in your mouth that is failing so going streight to the valve is the quickist way of sorting it. If however you enter a wreck, hit somthing and there is a sudden jacuzi behind you it could be anything so Isolation is the best option here.

Unless you are totaly confident in your choice of action it is best to stick to one fixed course. So Isolate, Locate problem, fix or abort. Is my prefered method.

ATB

Mark Chase
 
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