If I'm not mistaken, there are then four failure modes that would require
you to isolate:

1) burst disk blow-out (non-issue if disks are plugged)
2) 1st/2nd stage failure PLUS knob failure (breakoff)
3) tank neck o-ring failure (pretty unlikely, but still in the running)
4) broken manifold bar (hope you only broke one side - this one scares me a
little.  It's the only one I can think of where you wish you didn't have the
manifold)

Any others anyone can think of, or anyone disagree with the above?

Also, I'm looking for a source for stainless or brass plugs to replace my
one-piece burst disks.  Any suggestions?  Or I could get a shim kit (as
George suggested) and put a shim underneath them, but I'd like some feedback
from the group that this is the right method, even for one-piece burst disk
assemblies.  Thanks.

Cam


> From: "George Irvine" <kirvine@sa*.ne*>
> Date: Thu, 19 Apr 2001 18:34:44 -0400
> To: "Jiri Stetina" <jstetina@ne*.cz*>, <techdiver@aquanaut.com>
> Subject: Re: Isolating Manifold Question
> 
> 
> We plug our manifolds as well. O ring failures are not even enough to call
> a dive on a proper manifold. That is a double barrel ring adjustable like
> the Sea Elite. When any of the knobs break off, this usually will not cause
> a leak unless the bonnet o ring goes, and again, not much of a leak. The
> real failure mode is a double failure: it is when the knob and the reg fail,
> either by freeflow freezup or by knocking the knob off and then failing the
> reg in any fashion. That is the only failure that requires isolation. We run
> low IP's to prevent the freezups, we run DIN regs to reduce the risk of
> breakoffs ( and in some cases replace the DIN connectors with stainless
> steel ones ), and we rig the regulators so that all of these contingencies
> including roll off break off of a knob are taken into consideration .  See
> my article on this on the WKPP web site.
> 
> ----- Original Message -----
> From: "Jiri Stetina" <jstetina@ne*.cz*>
> To: <techdiver@aquanaut.com>
> Sent: Wednesday, April 18, 2001 11:25 AM
> Subject: RE: Isolating Manifold Question
> 
> 
>> The reasons for diving with open ISO are clear. Imagine manifold withouth
>> burst disks  - European manifold. Which situation could be solved by
>> closing isolation valve? Leaking o-ring can be solved by closing the tank
>> valve. The leaking ISO istself? Manifold o-ring failures?
>> 
>> Do you have any experience that needs closing the isolation valve during
>> the dive?
>> 
>> Jiri Stetina
>> 
>> 
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