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

[tursiops]

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.

He's a troll. Apparently Australian. Possibly previous banned under another name.

 

[Akimbo]

Here are some images that might help divers who are not trained in isolation manifolds. Note that the "post valves" control flow to the regulators and the isolation valve allows each cylinder to be isolated.

 

[PfcAJ]

IIRC there was a dual fatality at Wayne’s World a number of years ago, and a closed isolator was a contributing factor.

Every time I touch a set of doubles I make sure the isolator is open. It certainly CAN cause a problem, but imo the problems are easily mitigated.

A roll on break off + free flow is probably the most serious situation that an isolator would address. I have personally had a right post valve strip on a dive, and the isolator would have been the last defense against a leak. Leaking burst disks are certainly a thing that happens, but in my experience they’ve been very slow.

 

[cerich]

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.

What should be and what is are often not the same. If a solution to an extremely rare problem causes more problems, then there is a problem. You can't ignore human factors in process.

 

[rob.mwpropane]

Ok.. for all you tech certified folks.. do you dive with the isolator all the way open, or just 1/4-1/2 open.. a few turns? In the event of catastrophic hell fire wouldn't it be easier to turn it 2 or 3 times to closed flow as opposed to ALLLL the way off?

The way I do it now is fully open when filling, fully open for travel and at the site, but closed all the way and then opened 2-3 good turns right before I get the doubles on my back.

Also, if I plan to whip from tanks at the SI for another dive I try to remember to close the isolator ~ 15 min or so before the dive is over so it's more gas for the next dive. (All OW stuff, no tech).

None of these were my ideas, just stuff I picked up from better divers (or maybe worse, Idk) along the way. Thoughts?

And @cerich I think you had mentioned pilots and their errors in a post due to the layout of the panel. It's also true that a lot of pilots have made mistakes not following a check list. I know CCR guys use them, or at least are supposed to. Gareth Locke supports them. Why not instill checklists more so than doing away with something "could" become beneficial 1% of the time? Honest question... not at all trying to criticize your post.. here to learn. Wouldn't a good predive checklist eliminate any issues with the isolator?

I was at the airfield a day after there was an accident. The pilot who had owned the plane for more than 20 years forgot to turn on the fuel pump. It's plain as day in the checklist, he just forgot to do it... after 20 years of doing it all the time. Thankfully he landed in an open field without injury and the plane only had minor damage. I think about that all the time.

 

[DAJ]

Why make excuses for others that don't use their equipment properly and blame their shortsightedness on a gear issue. Absolutely nothing wrong with an isolation manifold. If you don't intend to use it properly, then don't use one. I've used mine for decades and never had an issue. Same goes with any piece of diving equipment. Again, it's not the gear that causes more problems, it's the divers using the gear that don't use it properly and deflect their lack of attention to detail onto a piece of equipment instead of taking personal responsibility for their own actions.

 

[Lorenzoid]

Why not instill checklists more so than doing away with something "could" become beneficial 1% of the time?

I can only speak to the way I was taught, but the pre-dive check includes checking the position of all three valves of the manifold. And then, after tying into the mainline or at any other major waypoint in the dive, we check them again (along with gas, depth and time). We check the positions of the valves if the manifold bumps against something during the dive. And we check our gas every five minutes or so and were taught that if we don't see the gauge needle moving, the first thing that ought to occur to us is a closed isolator. With a "checklist" mentality, I don't understand how diving with a closed isolator can happen.

 

[rob.mwpropane]

I can only speak to the way I was taught, but the pre-dive check includes checking the position of all three valves of the manifold. And then, after tying into the mainline or at any other major waypoint in the dive, we check them again (along with gas, depth and time). We check the positions of the valves if the manifold bumps against something during the dive. And we check our gas every five minutes or so and were taught that if we don't see the gauge needle moving, the first thing that ought to occur to us is a closed isolator. With a "checklist" mentality, I don't understand how diving with a closed isolator can happen.

What about fully open vs 1/4 open?

 

[Lorenzoid]

What about fully open vs 1/4 open?

Your post was the first time I have heard of this partially-open method.

 

[Adobo]

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.

I read it a few times too and it just looked like word salad to me.