Manifold question

[jefffalcone]

Two questions really.

1. Does a manifold need to be 300 bar to be DIR? If so why? As far as I no there is no greater likelyhood of failure in a 200 bar than 300 bar. These are slang terms that have nothing to do with the opperating pressure.


2. I am under the impression that GUE requires all valves to have rubber knobs. I was just reading an arguement on OMS's website as to why the don't use rubber knobs. This is what they have to say:

OMS manifold valve knobs are manufactured from medium durometer plastic to prevent wedging and accidental turning should the manifold come in contact with the overhead environment .
Rubber has many drawbacks. It is subject to rapid UV deterioration and sudden failure, is usually a low durometer material, has a high coefficient of friction (it s grabby), and is therefore more prone to being turned by anything it comes in contact with. For example on a set of manifold doubles, the Divers left side valve knob (rubber) would wedge and turn to the closed position (unexpectedly shutting off the gas supply) more so than plastic. On similar note Cave divers discarded rubber cylinder boots long ago, after they discovered that they had a tendency to wedge in restrictions, causing the diver to become stuck.

Sounds convincing to me. Then again OMS is the manufacturer of the infamous BWOD and I'm sure they can justify that monstrosity too.

The reason I ask is I've found a good deal on a OMS 200 bar manifold. I'm taking fundies in a couple of weeks, and if all goes well I'll be taking some tech courses soon. So far I'm a fan of the DIR concept. At least I perfer a Hog set-up to traditional OW gear. I'm not sure if I'll take tech 1 with GUE or some other agency and I'm only taking fundies at the rec level for now, so the manifold question isn't important for the immediate future. I just don't want to buy something that won't work for me in the long run (did that once already). I'd like to know if I am properly informed on DIR requirements for manifolds, and if so, it would be great if someone can explain the reasoning behind these requirements.

Thanks

 

[Jasonmh]

Here is some info from the GUE website:

"Knobs should be spring-loaded and soft, with a metal insert that prevents them from being stripped. Divers should not use metal knobs. Rubber knobs are durable, shock absorbent, shatterproof and easy to turn. Divers should be aware that, if rubbed along an overhead, rubber knobs could turn inadvertently. Plastic knobs do slightly reduce the chance of a “roll off” but can be dangerous if, on impact, they shatter. Rubber knobs—like those found on the Halcyon manifold—are very robust, while softer plastic knobs—such as those found on the Scubapro manifold—also seem to resist breaking. However, hard plastic knobs break very easily and should be replaced at once. "

Equipment Configuration | Global Underwater Explorers

If the plastic knob shatters or breaks it could lead to a situation where the valve could not be turned.

I would doubt that a GUE instructor would allow to you take the class with the plastic knobs, but it is always a good idea to discuss gear choices with your instructor or potential instructor.

EDIT - If you are seriously considering GUE training, I would stay away from the manifold you mentioned. Here is a pretty inexpensive one that meets the requirements:

Great deal on SEA ELITE 300 BAR 3/4 MANIFOLD from Divers-Supply.com

Hope that helps.

 

[rjack321]

I have some rubber knobs which are approaching 15yrs old. While they have a bit of a white haze on them and don't look new, they are years and years away from being so UV damaged they need replacement.

 

[jefffalcone]

Thanks Jasonmh. I just bought the manifold you suggested. It was only $60 more than the used one I was considering, and I know it won't lead to future problems. I am signed up for fundies already. Depending on how I feel about the experience I may or may not continue my education with GUE.

Once again, I appreciate the advice.

 

[jefffalcone]

I am still curious about the 200 bar vs. 300 bar question. Does anyone have any input on that?

 

[Gombessa]

I think it's Dive Rite Express that has a good, oft-cited article about 200bar v. 300bar manifolds. The short answer is that 300bar is *not* structurally stronger than *200* bar - the extra threads, they do nothing. The reason for their existence is simply to make them incompatible with low-pressure gear (such as yoke inserts and converters). In fact, because the threads cause the sleeve to stick out farther, 300-bar manifolds are more prone than 200bar manifolds to damage.

Btw, less than two weeks ago I had an OMS plastic knob break on me. It didn't "shatter" into pieces, but while lifting the tank some piece inside the knob broke through the plastic and now it turns turns freely without catching the metal screw it's supposed to turn. I'll take a soft rubber knob any day :/

 

[jefffalcone]

I've read the diverite express article. That's partially why I asked the question.

I don't know where I heard that GUE required 300 bar manifolds and it seemed odd to me. I just read through their website and I can't find any reference to 200 bar vs 300 bar, so I'm guessing that I was misinformed.

Thanks for the reference Gombessa

 

[nadwidny]

I've read the diverite express article. That's partially why I asked the question.

I don't know where I heard that GUE required 300 bar manifolds and it seemed odd to me. I just read through their website and I can't find any reference to 200 bar vs 300 bar, so I'm guessing that I was misinformed.

At one time there was a preference (not requirement) for 300 over 200. It may be on Quest where JJ spelled out why (If I have the time I'll look for the reference). However showing up with a 200 Bar manifold is not a deal breaker and I've never been at a DIR course where a student with a 200 setup was advised to change.

 

[b1gcountry]

I asked the same question, and I got the answer from my DIR-F instructor that the regs you will be using will all be 300bar anyway, so the only thing the 200bar gives you is that you don't have to screw them in as far, which isn't a big concern. The threads will be more exposed on the 200bar valves, and this will make it easier to get entangled. The extra threads also give you [marginally] greater security. He went on to say that it isn't the biggest issue in the world of diving, and he wouldn't kick me out of the class if I showed up with a 200Bar manifold, just that the 200 bar has no real benefit to a DIR diver, and you might as well go for the 300 bar.

I switched all my regs over to DIN, and I'm glad I did. Trying to deal with DIN/Yoke is a pain.

Tom

 

[SparticleBrane]

I have the opposite feelings:

Some fill stations (such as the one at my school) only have yoke connections. If you want to fill your DIN tanks, you either need the 200-bar DIN-to-yoke insert, or a fill block. Since I don't own a fill block I occasionally have issues filling the 300-bar manifold on my Al80s.

Personally I like the convertibility issue with regards to 200-bar DIN. It can do both DIN and yoke just by putting in an insert -- easy as pie. Just make sure you don't lose the insert...