The Isolation Manifold, lessons not learned and a small defence of the IUCRR

[ofg-1]

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My instructor explained that the correct answer was that the isolator was closed, so all the gas was coming out of one cylinder. I pointed out that in a normal gear configuration, if the manifold was closed, the diver would not see that I was going through gas too quickly, the diver I would see that he was not going through gas at all. The SPG usually comes off the left post, and the diver usually breathes off the right post. The question would only make sense of the diver had made the highly unusual decision to run the SPG off the right post. My instructor, quite surprised, admitted that I was right and he had never thought of that before. Evidently, neither had any of his students.

So let's say that in real life a diver with an isolation manifold suddenly has an OOA response during an inhale because of a closed isolator. That means that the diver had not yet checked the SPG at any point in the dive.

I actually had this happen at Madison Blue a number of years ago. I have been diving side mount for over 20 years, and was diving with a partner that was backmount. She had E7 80's, I had 85's. As I was getting close to thirds, she signaled out of air. Her spg read full. I made an assumption that her spg failed, so she went on my long hose and we exited, no problem.

It was not until we were taking the gear off that I even thought about an isolator, I had been diving side mount for years. When I opened the isolator, the tanks equalized. We had our tanks filled that morning at CE. When we got in the water, I did check that her valves were on, but did not think about the isolator.

When I started cave diving, a lot of people were still using homemade manifolds made from 2 K valves and a silver soldered tube between the two. Everything was yoke regulators. The Sherwood dual valve manifold was a big improvement, but they used crappy O rings. I changed them every dive. If you blew an O ring you still had to shut a valve down. I think the isolator grew out of the gear we had at the time.

 

[huwporter]

There's nothing wrong with manifolds there needed with multiple tanks, the isolator is useless and creates problems. It introduces more potential leaks and in the time it takes to close the isolator the valve could be closed. I've never used an isolator the minute I saw one I thought why would I add that to my tanks, what will it do for me?

If this were true, you'd be better off still with a massive single tank with a Y-valve.

 

[Gone for diving]

I actually had this happen at Madison Blue a number of years ago. I have been diving side mount for over 20 years, and was diving with a partner that was backmount. She had E7 80's, I had 85's. As I was getting close to thirds, she signaled out of air. Her spg read full. I made an assumption that her spg failed, so she went on my long hose and we exited, no problem.

It was not until we were taking the gear off that I even thought about an isolator, I had been diving side mount for years. When I opened the isolator, the tanks equalized. We had our tanks filled that morning at CE. When we got in the water, I did check that her valves were on, but did not think about the isolator

Have a hard time understanding how the isolator valve can be forgotten....

It is something that you do on a S drill...
It even reminds you I what direction valves needs to be turned...

Sure in this case switch to long hose, (i have no problem with that) (and you made it out no problem)
But spend 10 seconds figuring out if the valves are correct.

I am more concerned why the spg being in question was assumed bad,
And what was wrong with switching to your backup reg that's under the chin?
It would have worked.

I don't understand how and why people when filling, are playing with the isolator and getting it wrong, you are turning valves all day, it's the same directon for every valve..

( A LH rotation valve will fix nothing, in fact I think it will really screw things up)

I am also very concerned that If valves on doubles is confusing a certain population of people, definitely don't get a rebreather.

I believe you should know,
how, why, and what for,
On all your dive gear...

I am afraid most people, learn the right movements, but at some point forget why. And fail to understand what is happening with their life support,

Life support does require intelligent input from the diver,
checking gauges,
opening and closing valves,
switching regs,
knowing what's in the tank,
Etc

 

[rob.mwpropane]

Have a hard time understanding how the isolator valve can be forgotten....

It is something that you do on a S drill...
It even reminds you I what direction valves needs to be turned...

Sure in this case switch to long hose, (i have no problem with that) (and you made it out no problem)
But spend 10 seconds figuring out if the valves are correct.

I am more concerned why the spg being in question was assumed bad,
And what was wrong with switching to your backup reg that's under the chin?
It would have worked.

I don't understand how and why people when filling, are playing with the isolator and getting it wrong, you are turning valves all day, it's the same directon for every valve..

( A LH rotation valve will fix nothing, in fact I think it will really screw things up)

I am also very concerned that If valves on doubles is confusing a certain population of people, definitely don't get a rebreather.

I believe you should know,
how, why, and what for,
On all your dive gear...

I am afraid most people, learn the right movements, but at some point forget why. And fail to understand what is happening with their life support,

Life support does require intelligent input from the diver,
checking gauges,
opening and closing valves,
switching regs,
knowing what's in the tank,
Etc

I had a guy working for us at the company. Was a 50/50 shot he would screw things together the right way.. lefty loosey and all that... I swear he got it wrong 90% of the time. I would watch him try to "loosen" fittings together.. I just couldn't understand it.. but he could open and close a soda bottle?

When I used to fill tanks at a dive shop the last thing I check is isolator and the 1st thing I check before I leave.

I don't understand how people get in those situations either, but having never been in one I can't comment. No idea how I would react in that situation. I would like to think I would switch regs and check valves asap.. but I really don't know.

 

[Gone for diving]

lefty loosey

I like that saying, but it's not clear, top left or bottom left? When I was a kid it confused me,,
I found clockwise is tight,
Counterclockwise is loose more clear,
But now a days it probably means nothing to the younger generation...

When I fill a J valve on double tanks for my DH,
I like to double check by closing in for 10 seconds and l when I open it, hear if it transfers...

 

[oya]

A left or right post valve failure would result in total gas loss in fairly short order.

 

[Celt]

If this were true, you'd be better off still with a massive single tank with a Y-valve.

You don't nead an isolator valve to get the use of both tanks, all multi outlet manifolds will deliver the gas in both tanks to either outlet. But apart for independent doubles technically that's true,

 

[cerich]

A left or right post valve failure would result in total gas loss in fairly short order.

A catastrophic one. That said, how many of those really happen? It's either the neck o ring or burst disc. Having been a resort instructor, I can tell you with a good degree of certainty that at any given time in a high volume cattle boat operation that upwards of a quarter of the tanks have slightly leaking neck O rings, yet them giving away catastrophically? yeah no. It is possible, it surely must have happened somewhere sometime, but is is beyond rare. The burst disc fails when filling or in the sun with a filled (often slightly overfilled) tank catastrophically, not while diving. Again, a couple may have happened somewhere sometime , but virtually never. I have personally witnessed MANY divers discover the isolator is shut when they "run out of gas" while diving, many more that were shut during fill and they have half the gas they expected. I have seen one diver simulate a Poseidon missile when they "ran out" of gas at 70 m, when I reached them on the roof he said "ran out of gas, missed 30 mins deco" and as I towed him checked the isolator and it was shut, opened it, screamed to boat to have them bring us bottles and took him back down to 25m with me no mask and on his long hose... in shorts and a t in cold water until other divers got to us and I came back to surface. He ended up fine. I know of many cases of deaths and also injury from the isolator being **** during fill or during dive and not caught until too late.

A manifold with a non isolation x over you can still isolate a malfunctioning regulator or leak where the reg meets the manifold, that is fairly common issue.

 

[DAJ]

It’s not the isolation valve that’s the problem, it’s the diver. If you decide to use an isolation valve, make sure it’s open. It’s really not that difficult or complicated, check the damn valve. If a diver runs out of air ( in the example above), that diver is not only at fault for not making sure the valve is open, they obviously don’t pay attention to their pressure gauge or their computer depending on how they have it configured. If they did, they would see that their air was getting too low and got help from someone or noticed their air pressure was not dropping at all during the dive which would also indicate an issue. While an isolation valve may buy you time to figure out what is wrong during a major failure and hopefully saving you a bit more air in the process, you can’t save someone from themselves if they don’t check their gear properly.

 

[boulderjohn]

Your instructor is definitely right and to my knowledge was appeasing you. Anyone who is, or has been technical diving should have been trained or should have experienced a shut isolation valve and know to switch to backup. Monitoring turn pressure is crucial at depth.

I read this 5 times and still have no idea what you are talking about. I guess my reading comprehension is not what it should be.