Benjamin Conversion vs Isolation Manifold

I just read this on the ICURR website. I'm not sure I fully agree but it does seem worth noting - especially in light of the recent Eagle's Nest mix error incident:

http://www.iucrr.org/manifolds1.htm
http://www.iucrr.org/manifolds2.htm

I once talked to a dive store owner who was very proud of his supply of non-isolation manifolds. At the time I thought his attitude very archaic (and as I dive independents anyway of no consequence to me) but in light of these recent articles his opinion may not have been as odd as I first thought.

Anyway there are bound to be any number of opinions on the subect and it may be time for another stirring discussion. ;-)

There are advantages and disadvantages to everything. One thing I have to disagree with Jeff's article on is the number of incidents in which an isolation of the manifold was utilized. I doubt that most events in which an isolation did occur but did not result in a fatality get reported. I personally have had a failure of a burst disk on a dive 4000 feet back in Hole in the Wall where I had to isolate, and I did not report it to anyone. I know of several other divers that have had an issue with their main tanks and have been forced to isolate and turn the dive.

I think if one is concerned enough about the isolation manifold being a failure point then the solution is to dive independent tanks such as sidemount or independent doubles. If you dive a manifolded set of tanks then I think an isolation valve is better than not.

On the other hand ...

I have been on three different dives when there was a problem (or perceived problem) and the diver or buddy closed the isolator. In all three situations closing the isolator was the wrong course of action.

Russell

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Originally Posted by Gary

I just read this on the ICURR website. I'm not sure I fully agree but it does seem worth noting - especially in light of the recent Eagle's Nest mix error incident:

http://www.iucrr.org/manifolds1.htm
http://www.iucrr.org/manifolds2.htm

I once talked to a dive store owner who was very proud of his supply of non-isolation manifolds. At the time I thought his attitude very archaic (and as I dive independents anyway of no consequence to me) but in light of these recent articles his opinion may not have been as odd as I first thought.

Anyway there are bound to be any number of opinions on the subect and it may be time for another stirring discussion. ;-)

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Gary,
Ck these two posts out that I penned on this forum a while back:

1.
Posted: Sun Aug 14, 2005 11:41 am Post subject: Rolloffs & isolater valves w\DS manifolds
Without going into a lot of detail, I'm looking to replace the Diver's Supply manifolds on my steel 104's & 72's. I experiended a 'suprise' roll -off over this past week end, & that was a scary thing. This is the 2nd time this I've brushed an overhead, with one of the knobs, & it shut my air off-! On my original twin valve set-up, {yoke} I never once had this happen, as the valve profiles are smaller, & the furled knobs are also a lot tighter to turn on or off. What are the preferred manifolds that everyone is using today, & the sources to find them. Any suggestions or information will be greatly appreciated.
Thanks,

2.
Posted: Wed Nov 30, 2005 6:09 pm Post subject: UWS: Isolater valves VS Dual-Valve Mflds
In Jeffrey Bozanic's latest issue of Cave Diving Accidents 2002-2005 he relates his issues concerning the above named manifolds. In his analysis, he states that " he feels that the Dual-Valve manifold has a much cleaner & nearly accident free history of usage"-! Using both of these manifolds on my back-mounted doubles, I can back up what Jeffrey says about which is safer to use-! In short, with the current Isolater manifolds being marketed, I along with a number of other cave divers have experienced 'roll-offs' in varying degrees of threatening situations-! I don't trust the Isolater- valve set-up the way I do the dual-valve manifold. I hope everyone here gets to read this excellent issue of the CDS's 'Accidents Review'-! It has an abundence of helpful information allowing us to hopefully become more aware of our diving excursions & the equipment that we choose to use-!


You make a lot of sense about this issue-! Wishing you & Kat a Merry Christmas & Happy New Years too-!

Jack 8)

Personally, I believe having an isolator valve is safer than not having one. Just make sure it's open when getting your tanks filled and before making a dive.

I had a situation about 3 years ago in Madison Blue while doing a stage/scooter dive to the entrance of Potter's Delight. After dropping them off and making the trek to The CourtYard with full doubles, I was surprised to see that I was using gas much faster than I did on a similar dive a year before. I turned on thirds and made the trek back to my scooter/stage. At that point, I discovered that my doubles contained less than 700 PSI of gas. During the 1700' trek back to the entrance(which was delayed briefly by a group of 6 divers who wouldn't give me the right-of-way), my doubles ran dry and I had to switch to my stage bottle. After exiting and gearing down and checking my doubles, I discovered that the isolator valve was completely turned off and that one tank still contained 3600 PSI of gas. My first thought was that it had rolled off while negotiating the Potter's Delight/Rockey Horror tunnels, but I was more inclined to believe that it was turned off by the fill station operator after the tanks were filled. I never checked it before starting the dive, so I'll never really know.

That is the point they are making you had a problem that would not have occurred if you did not have the valve. One of the points of the article is the author says they have not heard of many incidence where the isolator was used to facilitate a safe exit. This goes to show folks are not reporting enough. Look at the IRAP on this board. The last reported incident was 5/12/05


"I isolated and shut down the post, thinking that it might be reg. No dice, so I turned the post back on and started to breathe down the leaking tank.


I figured that I had plenty of air, but I was in no mood to play around. I left my reels and headed on out. Pulling and pulling and kicking. It is amazing how fast Devil's will spit you out when you try hard enough. "

Was this incident reported to the NSS-CDS? I don't know. Was this the lst incident to occur amounst this group?
We learn when we relate our experiences to others. I encourage you to write up incidences.

Curt

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Originally Posted by curtschu

That is the point they are making you had a problem that would not have occurred if you did not have the valve.

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I write programs for a living. I am not trying to be harsh here or call anyone an idiot, but one thing I have learned while programming is that if I make a program idiot proof then someone will invent a better idiot. The point being that you design things to fulfill a certain purpose, and if people misuse the item in question it does not mean that the design is bad. It more likely points to complacency, lack of training, lack of knowledge, etc...I tend to be paranoid about the isolator being open during the filling process, and while putting my tanks on when diving backmount. Again, I am not bashing anyone, but I fail to see the logic in calling into question the design of a piece of equipment that seems to work exactly perfect, even when we may not want it to.

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Originally Posted by curtschu

I isolated and shut down the post, thinking that it might be reg. No dice, so I turned the post back on and started to breathe down the leaking tank.

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That is my report. I never reported it to the NSS-CDS as I was/am not aware of a reporting mechanism.

Regards,
Peter Doege

I believe the IRAP forum was created to help deal with this concern that lots of 'stuff' was happening with people but it wasn't being reported. I hope more people start reporting their incidents so a good data base can be generated to do exactly what Bozanic was trying to accomplish with the accident analysis (see recent UWS publication).

I am unaware of any other incident reporting mechanism for the various dive agencies.

The inside cover of the UWS issue we are talking about is the reporting form. Also at this URL http://www.caves.org/pub/aca/94index.html
there is a link to an online form. The link is broken but I just sent an email to Bill Putman to let him know.

Curt
Found this link on the caves.org site

http://atl.putnamconsulting.com/~aca/acaform.html

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Originally Posted by Angie Reim

I am unaware of any other incident reporting mechanism for the various dive agencies.

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Unless there is a death (or rescue) performed by the IUCRR I know of little other then the IRAP or the various forums. I guess a person could write an article for one of the various cave journals.

At least with premix nitrox there is less threat of breathing pure O2 off one tank if the isolator gets closed. Hearing about CaptainSpeleo's experience and the tanks running out... thank goodness he had an independent air supply also.

I've always hated that the isolation valve is a failure point common to both tanks. Especially the isolator valve itself (valve stem and knob leaks) that are posibilities introduced by the addition of a knob there. That is why I have always refused to use manifolded doubles (even though there have been few recorded problems with the setup).

I think a bar with no isolator is far worse - meaning any problem effecting one tank/valve/manifold will also effect the other. Not being able to isolate such problems common to both tanks is far worse then having a few points of common failure.

The mix/fill issues to me are an attention issue. Easily covered by checking pressure and mix on each tank or just checking the isolator open. I have had a valve that failed shut once - even with the knob open the valve seat stayed closed - even removed from the tank and against full pressure of a fill whip. Operating the valve might not be sufficient to detect such a failure in the isolator valve and would be sure to only add confusion to the various issues that might come from a closed isolator valve.

(Merry Christmas!)

If you look at the form at the link in my post that works it is pretty self explainitory. One of the "Result" catagories is "No Consequence (no one hurt, problem solved but worth reporting)"

Is there a location to see the reports?

As far a I can tell it is the report you get from the NSS once a year with your membership.

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Originally Posted by CaptainSpeleo

Personally, I believe having an isolator valve is safer than not having one. Just make sure it's open when getting your tanks filled and before making a dive.

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Excellent advice. More than once have I found isolators closed while starting to fill at Cave East. I wonder why anyone would close the isolator after a dive?

They should be locked open with a breakaway indicator tag - so that if the tag is broke you can visiably see that you should check the valve position and put a new tag on. :) :wink:

Gary, I got a reply from Bill Putnam on the availability of the reports.
Right now it is only the yearly report. NSS has not given perrmission to post them on the web. You can purchase current and back issue as available through the NSS.

Thank you for checking. It is nice that they are collecting the information even if most will never see it.

I wonder if the reports are checked for veracity or whether people are just submitting bogus reports in support of their favorite theories - and how the info will be used. Many of the IRAP reports were clearly questionable in different ways depending on the author.

But you can't have everything I guess.