Manifold

[kancho]

What is the difference between a rotation cross bar manifold and an isolation manifold

[CompuDude]

Originally Posted by kancho

What is the difference between a rotation cross bar manifold and an isolation manifold

I don't think I've ever heard of the first one, but it sounds like either 1) simply another name for an isolation manifold (since the cross bar does rotate) or 2) something you don't want to bother with.

[fire diver]

Originally Posted by CompuDude

I don't think I've ever heard of the first one, but it sounds like either 1) simply another name for an isolation manifold (since the cross bar does rotate) or 2) something you don't want to bother with.

LOL!

I think I know what you are asking. There are two types of doubles manifolds. One kind has a seperate, center "cross bar" that connects the valves of the two tanks. These have a valve in the center for seperating the air between the two tanks in case of a leak on one side.

The other type is a one piece unit (valves and cross bar combined), that the tanks are mounted on to. These are an older style of manifold and not commonly used today (too the best of my knowledge anyway).

Actually, there is a third type from the 1980's. It was a stand-alone piece that connected to two K-valves and made two single tanks into a temporary double. These have a single reg mounting point in center of the cross bar. These are generally considered unsafe by modern standards. I own one and like to play with it from time to time, but not for real dives.

Did this answer your question or confuse you further?

FD

Edit- after re-reading your question, I think they are two terms for the same thing (the first example I gave).

[kancho]

I asked this because OMS seems to have 2 different types of manifolds but they both can adjust.
OMS SCUBA Valves & Manifolds http://www.OMSdive.com
1 is rotating crossbar and the other is Captured O Ring.. Which is better? I think they do the same job/

[CompuDude]

Either is fine, tho I'm not sure of the difference offhand. I'm not devoting a lot of thought to it right now, however.

I'd skip OMS, save some money, and just buy the Salvo 300 bar manifold, personally.

[fire diver]

The pic is worth a 1000 words. Some people feel that the multi o-ring version is safer becuase it has built in redundency. Others think those are just silly worrying (sp?).

So cave divers like the barrel oring version (rotating) becuase it can be set just loose enough to rotate backward instead of possibly breaking if it should hit the ceiling.

How hard are they planning on running into something?

[in_cavediver]

Originally Posted by fire diver

The pic is worth a 1000 words. Some people feel that the multi o-ring version is safer becuase it has built in redundency. Others think those are just silly worrying (sp?).

So cave divers like the barrel oring version (rotating) becuase it can be set just loose enough to rotate backward instead of possibly breaking if it should hit the ceiling.

How hard are they planning on running into something?

I like the barrel o-ring version for two reasons. First, it allows you to use bands with looser tolerances. IE, you can always 'tweak' the tank valve distances if needed. The other reason, if you take a stiff blow to the isolator, the face seal or captured o-ring version is more prone to failure in my opinion. Since they both cost the same, why go for the inferior version.

As for test, I friend dumped a set of 104's off the tailgate when rounding a curve doing 20mph. (tailgate went too for the record as did a couple can lights!). The isolator was a barrel design and literally was out of alignment by 1.25 inches. The right post valve knob was literally sheared off. Tanks still held 3800psi.

[texdiveguy]

I use and prefer a 200 bar rotating cross bar manifold myself. A better design in o-ring configuration and the 200 bar is more versatile.

[cummings66]

I use 300 bar rotating cross bar manifold for mine. I think from all the reading I've done the double O ring is a better design and should have less trouble.

I've heard of concerns with the OMS when it comes to cave diving, seems they think hitting the ceiling can damage them, I don't know. I do know this though, you can get pushed hard enough by current sometimes that if you did hit you would scrape it hard enough that I bet it would rotate on you, or break trying.

Bennett Springs had 175 million gallons flow rate not long ago, that amount of current could push you so hard into the ceiling that you'd be a pasty smear on it. Actually, the park closed it at that point because it's dangerous.

[kancho]

Thanks.. Can you put a 300 Bar manifold on LP tanks if you change ur burst discs?