Crossbar and isolator valve: do they help?

[PfcAJ]

Another thing to consider is how many incidents have occurred that are attributable in some way to the presence of the isolator that would not have occurred in the absence of the isolator. For example, how many people have discovered an isolator that was closed at some point when it shouldn't have been?

I know of one serious accident and one fatality that both had isolator closures as contributing factors.

Gotta check it. It'll cook your goose.

 

[Doby45]

Another thing to consider is how many incidents have occurred that are attributable in some way to the presence of the isolator that would not have occurred in the absence of the isolator. For example, how many people have discovered an isolator that was closed at some point when it shouldn't have been?

That is the reason that the one valve I have a Vindicator on is my isolator.

 

[BRT]

Right post roll on/ valve break followed by a free flow would cook your goose without the isolator, plus the inability to isolate in event of an o-ring or burst disk issue (and everyone in America has burst disks).

I have two friends who have had in-water burst disk issues. It happens, even if it's rare. I'm not too keen on drowning so I'll keep my isolator and make sure it's open

Will turning off the tank that has the blown disc or the extruded ring not protect the other tank?

 

[Doby45]

Will turning off the tank that has the blown disc or the extruded ring not protect the other tank?

No it will not. If the isolator is not closed the other tank will drain right along with the affected tank.

 

[Patoux01]

Not too sure why you'd die for not having a manifold. You'll die for having stupid gas management with independents (eg not switching tanks until the first one is almost done), but I don't think one can say that a manifold is inherently safer than independents.

As for the isolator... This is an interesting article Interview with Bill "Hogarth" Main | X-Ray Mag

 

[Centrals]

This is an interesting article Interview with Bill "Hogarth" Main | X-Ray Mag

On my IANTD tec wreck training, the manual also explain the reason for the inflator hose comes from the left post. Eventually I switched to right post because of so many -ve comments from the others!!!

 

[Lorenzoid]

That is the reason that the one valve I have a Vindicator on is my isolator.

I may replace mine with a Vindicator someday--I eyed up that option when I ordered the manifold from DGX. But I decided for my first set of doubles, while I'm still learning, I'd just force myself to check more often. I didn't bother asking, but I figured it's probably what the GUE guys would advise.

 

[northernone]

I've seen burst disks blow, I've seen neck orings catastrophically fail. I'm not going anywhere important without two adequate independent airsources. If that's independent doubles, manifold doubles and isolator, single + stage or SM.

Having all your gas in one vessel or eggs in one basket seems unnecessarily risky. I'd rather not be headed to OOG as a result of ONE failure. Darwin dives with me enough when it takes cascading failures.

Would I be understanding right those who don't want an isolator it is because they calculate the risk of an unlikely neck/tank/valve failure being less than the added risks of having an isolator which can fail/task load/get closed in error? I too have heard of the fatalities/near misses where the isolator was closed unnecessarily and compounded a bad dive.

I prefer sidemount because I can see and manipulate the tanks easier. Fixing something in front of me just seems easier than behind my back. In team diving it's perhaps more convenient to address issues back mount?


Regards,
Cameron

 

[kelemvor]

Do sidemount divers plan their gas based on loss of the most critical cylinder at the most critical point?

Sort of. You try and keep the tanks close to each other with respect to gas content. Partly for that reason, partly to help keep you balanced. You don't want a full tank on one side with an empty tank on the other. If you're diving rule of thirds, you've always got more than 2/3 of your gas in the tanks. Lose half of that (one tank) and you should still be able to get out.

 

[KevinNM]

I may replace mine with a Vindicator someday--I eyed up that option when I ordered the manifold from DGX. But I decided for my first set of doubles, while I'm still learning, I'd just force myself to check more often. I didn't bother asking, but I figured it's probably what the GUE guys would advise.

I can't tell you want they advise, but I spent the 45 bucks. However I haven't seen them on rental tanks. You should be verifying valves before you dive (and if you find the isolator closed or open the isolation valve pre-dive and hear gas moving it's time to get out of the water and analyze both posts) and in theory every 5 minutes or so during a dive.