Twin tanks

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Hey, what about connecting the two first stages with an hp hose between their respective hp ports???

If it works ??? it could save the extra SPG and keep the air supply balanced between the two tanks, and also be less costly than a manifold.

Just asking!!!:idea:
 
There is also a removable manifold, sometimes called a "Travel Bar Manifold" used to connect two single tanks to one regulator. They are not carried by any US suppliers but you can sometimes get them on eBay. The bottom picture on this page from an Aussey valve manufacturer shows what they look like: Sea Hornet Valves & Manifolds

They work well, but not with soft bands.
 
With doubles you don't need a manifold, but you may want one.

The manifold makes gas management and fills easier. If you're diving anything other than air, an open manifold assures you that you have the same gas in both tanks. Partial pressure blending in a set of doubles with an open manifold is just like doing it with one tank. Toping is simple, but with two independent tanks that have different remaining pressures, you may have to empty both tanks if you're topping with a different gas or such. There are endless scenarios, but the bottom line with gas is, doubles with an isolator is just like dealing with a single tank, and independent doubles is like dealing with two.

When diving doubles with a manifold, the tanks will breath down evenly, so there is no futzing around with switching back and forth between two tanks. You can isolate them if you want and have independent doubles, so you have a choice. But with independent doubles they are always independent.

Think about air shares with independent doubles verses ones with a manifold. Which reg will you hand off? Can you use a standard doubles configuration with one long hose and one bungeed back-up? Sure, you should always have enough gas in each independent bottle to get your buddy to the surface, but many times during the dive the amount of gas in each bottle will be different, making air sharing gas management more difficult, verses just handing off a primary reg which you know has the two of you sharing all the available gas.

It's why you can hit a boat or beach with a crowd of divers with doubles and be hard pressed to find independents. Sure, it possible, it's divable, and in some travel situations it may be the only option. Buy if you have a choice, is it preferable?

Not for me.
 
Hey, what about connecting the two first stages with an hp hose between their respective hp ports???

If it works ??? it could save the extra SPG and keep the air supply balanced between the two tanks, and also be less costly than a manifold.

Just asking!!!:idea:

Over at ScubaToys, they have a video of a cut HP hose. It takes a very long time to drain the tank.

I think the internal passage to the HP port is quite small. I'm not sure it would be big enough to provide air for breathing.

Richard
 
With doubles you don't need a manifold, but you may want one.The manifold makes gas management and fills easier.

If you're diving anything other than air, an open manifold assures you that you have the same gas in both tanks. Partial pressure blending in a set of doubles with an open manifold is just like doing it with one tank. Toping is simple, but with two independent tanks that have different remaining pressures, you may have to empty both tanks if you're topping with a different gas or such.

Why should he care, that's the tank jockey's job


When diving doubles with a manifold, the tanks will breath down evenly, so there is no futzing around with switching back and forth between two tanks. You can isolate them if you want and have independent doubles, so you have a choice. But with independent doubles they are always independent.
Rule of thirds, only 2 switches are required
Think about air shares with independent doubles verses ones with a manifold. Which reg will you hand off? Can you use a standard doubles configuration with one long hose and one bungeed back-up? Sure, you should always have enough gas in each independent bottle to get your buddy to the surface, but many times during the dive the amount of gas in each bottle will be different, making air sharing gas management more difficult, verses just handing off a primary reg which you know has the two of you sharing all the available gas.

Doesn't matter which one you hand off if you observe rock bottom gas management. And if both divers are diving independant gas sharing should never be required since an OOA failure is virtually impossible

It's why you can hit a boat or beach with a crowd of divers with doubles and be hard pressed to find independents.

That's because most divers are lemming who care more about looking like the cool kids than applying sensible solutions to their diving:shakehead:
 
A lot of shops that I have seen charge for two fills with independant doubles but only one fill for manifolded doubles
 
Over at ScubaToys, they have a video of a cut HP hose. It takes a very long time to drain the tank.

I think the internal passage to the HP port is quite small. I'm not sure it would be big enough to provide air for breathing.

Richard

Possibly, but that connection would serve only to equilibrate pressure between the two tanks. The diver would receive air in a normal fashion from his primary first stage.
It remains to be seen if the hose would let enough air to keep the two tanks at equal pressure.

A bigger diameter hose would then be required. It would make for an economical alternative to a complete manifold setup.
 
It's not the hose diameter, it's the tiny hole in the end fitting. Simple to drill out. 1/8" would be more than enough.
 
How big is the passage inside the first stage?

Richard
 

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