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brojack17
03-20-2010, 00:52
I was on the ST site and noticed their doubles setup. It appears that two first stages are necessary.

http://www.scubatoys.com/store/tanks/pics/AL80DoublesSetup.jpg

At the NASA Neutral Buoyancy Laboratory, they have a different setup that only requires one first stage (at least by the looks of it).

http://www.facebook.com/photo.php?pid=228150&l=ff049f921c&id=100000221405478

Since I work with the engineers and not the divers, I don't really have the people there to ask. What's the difference? How do you take two first stages to one second stage?

Smashee
03-20-2010, 02:02
What's the difference?

More redundancy. If you lose an o-ring on the NASA setup, you're not going to be able to continue the dive without losing gas. It has a single point of failure. On a scuba manifold, you can shut down the offending side and switch to the other, giving you redundant air.

comet24
03-20-2010, 05:52
NASA is likely using these in a pool, in clear water with safety divers around.

In wreck and cave diving you want redundancy. This way is something happens you can shut off one of the tanks and still have half of your gas supply. With standard doubles like the ones on ST site you uses two first stages. One 1st has your primary reg. and inflator hose. The other 1st stage has your HP hose(gauge) and you backup 2nd stage.

This style setup also has a isolation valve between the tanks(it's the knob facing up in the middle of the setup in your pic.) With that valve open when diving your using air from both tanks equally. If something goes wrong you can close that valve and isolate the problem.

jbres1
03-20-2010, 06:05
If you want to, you can still find that type of manifold on E-bay. Its old school as far as manifolds go.

Jim Breslin

DivingCRNA
03-20-2010, 06:59
NASA is likely using these in a pool, in clear water with safety divers around.

In wreck and cave diving you want redundancy. This way is something happens you can shut off one of the tanks and still have half of your gas supply. With standard doubles like the ones on ST site you uses two first stages. One 1st has your primary reg. and inflator hose. The other 1st stage has your HP hose(gauge) and you backup 2nd stage.

This style setup also has a isolation valve between the tanks(it's the knob facing up in the middle of the setup in your pic.) With that valve open when diving your using air from both tanks equally. If something goes wrong you can close that valve and isolate the problem.

+1 Also tec diving.

DivingCRNA
03-20-2010, 06:59
If you want to, you can still find that type of manifold on E-bay. Its old school as far as manifolds go.

Jim Breslin

I have one.

brojack17
03-20-2010, 08:02
NASA is likely using these in a pool, in clear water with safety divers around.

In wreck and cave diving you want redundancy. This way is something happens you can shut off one of the tanks and still have half of your gas supply. With standard doubles like the ones on ST site you uses two first stages. One 1st has your primary reg. and inflator hose. The other 1st stage has your HP hose(gauge) and you backup 2nd stage.

This style setup also has a isolation valve between the tanks(it's the knob facing up in the middle of the setup in your pic.) With that valve open when diving your using air from both tanks equally. If something goes wrong you can close that valve and isolate the problem.

Yeah, NASA is using this in the pool. Max depth is 40' 6" and this is used by the rescue divers. They all carry a spare air tank too. Like this one (Spare Air Package 1-7 Cubic Foot reviews and discounts, Submersible Systems (http://www.scubatoys.com/store/detail.asp?product_id=SpareAirPak17)) The astronauts are in modified space suits that are tethered to the surface for air and communications.

It makes sense the level of redundancy necessary for tech diving and what they do at the NBL.

Thanks.

captain
03-21-2010, 09:16
NASA, the U S Navy, and commercial divers use the single outlet doubles manifold. I have several sets of doubles with the single outlet manifold. All I want is more gas, not look like a wet dive shop.

cbope
03-22-2010, 11:13
:smilie39:


NASA, the U S Navy, and commercial divers use the single outlet doubles manifold. I have several sets of doubles with the single outlet manifold. All I want is more gas, not look like a wet dive shop.