Low pressure manifold?

[ianr33]

I have thought of the same thing for side mount to eliminate using 2 high pressure gauges and 2 transmitters ($350 each).

There is a real simple way to eliminate the transmitters!

 

[elan]

I have thought of the same thing for side mount to eliminate using 2 high pressure gauges and 2 transmitters ($350 each). I designed my config using 2 6000psi stainless steel 1/8" needle valves and thread adapter, one each to the second high pressure port on each first stage regulator. Then installing a high pressure hose disconnect on both and a short flexible HP hose across the chest. I decided to use needle valves as a precaution if the disconnects failed, the air could shut off. Also the needle valves controls the air transfer between tanks to insure I did not "ICE" the regulator being used. If test shows the needle valves are not needed, you could take them off. The female disconnects (if they don't leak) on the HP port would be needed to insure disconnection of the hose does not drain ether tank.

Pushing the tanks ahead should not cause a problem, but I"m thinking of adding a HP swivel to insure not twisting the hose. Just in case though, IF I get to the testing stage, I would carry a 19 pony slung off the belt. Don't have any of this stuff around the shop except for the hose, so I would have to spend a couple hundred to try it out.

I have not had the time to pursue this and I'm not completely sure the tanks would equalize through the high pressure port on the first stage valve body. Looking at the schematics for the Scubapro MK25, the high pressure ports are branched off the inlet before the seat. One of the issues that may be a factor, is insuring no contamination gets into the hose when it is disconnected to get lodged in the seat inlet. I guess one could find a sintered filter to install between the needle valves and disconnects or disconnects and valve body.

no need to spend a couple of hundred dollars for that. your design does not take into consideration one important factor - the hole in the HP port is designed to transfere pressure staticaly. the small size of it will not be suffecient to provide adequate flow for breathing. look at HP gauge how slowly it charges when you turn the tank on. and this is with the little volume inside the gauge. There is no way you can feed a diver through that pinhole.

 

[OkByMe]

The OP was venturing forth with a creative idea, I'm on board with him. Creativity can only exist among those that don't resist change. I'm sure the same thing was said when someone suggested connecting 2 tanks together with a manifold... And the same with side mount. The same old "this is way it is done and it has always been done this way because I learned it this way" position. If it were not for Eli Whitney, we all would still be cutting wheat with a sickle.

A bad Idea will soon show itself, So I can go along with the position that a bad idea is still a bad idea. I'm not sure that the tanks will not completely equalize through the #56 hole in the High pressure port while breathing off the regulator and or using BC and/and dry suit inflation. The hole in the hose end to the pressure gauge is so small I can barley see it, it has to be at least a #80.

pony for the test safety - redundancy.

 

[rhwestfall]

no need to spend a couple of hundred dollars for that. your design does not take into consideration one important factor - the hole in the HP port is designed to transfere pressure staticaly. the small size of it will not be suffecient to provide adequate flow for breathing. look at HP gauge how slowly it charges when you turn the tank on. and this is with the little volume inside the gauge. There is no way you can feed a diver through that pinhole.

that was said back in post #8.....

 

[Superlyte27]

You are adding complexity where it simply is not needed. Two independent tanks is the best way. Lose an O-Ring in a first stage, second stage, or blow a hose, turn off that tank. Breathe on the other tank. Worse case scenario you can feather the valve or once your good tank dies, you can swap the regulator on the empty tank for the bad regulator on the tank that still has gas in it. (Yes, you have to hold your breath and not be an idiot to accomplish this).

If you're practicing good gas management, the good tank/reg should be able to get you out at any portion of the dive. KISS.

 

[Doppler]

The OP was venturing forth with a creative idea, I'm on board with him. Creativity can only exist among those that don't resist change. I'm sure the same thing was said when someone suggested connecting 2 tanks together with a manifold... And the same with side mount. The same old "this is way it is done and it has always been done this way because I learned it this way" position. If it were not for Eli Whitney, we all would still be cutting wheat with a sickle.

A bad Idea will soon show itself, So I can go along with the position that a bad idea is still a bad idea. I'm not sure that the tanks will not completely equalize through the #56 hole in the High pressure port while breathing off the regulator and or using BC and/and dry suit inflation. The hole in the hose end to the pressure gauge is so small I can barley see it, it has to be at least a #80.

pony for the test safety - redundancy.

I too am "on-board" with creative ideas, lateral thinking, questioning the status quo... however, experience with equipment design, deployment and, probably most importantly, the human factor when the wheels fall-off during a dive inform me when a concept intended as a risk-management tool is over-designed, unwieldy, and introduces several new failure points. Sorry, but I truly believe that you need to ask yourself the following questions before going ahead.

What problem(s) does {IDEA} resolve?
How likely to show itself is the problem that {IDEA} solves?
Is there a less complex solution?
Does {IDEA} need a user's manual, or diver intervention at depth?
If {IDEA} fails, what is/are the options for safe return to the surface?
Is this a better (simpler, faster) pathway than offered by any current solution?
Who will use {IDEA} and what will it require to bring {IDEA} to market?


Bad concept, in my opinion, and trying to hide behind the "change is good" smoke-screen does not change the facts.

By the way, some people STILL question the concept of joining two cylinders together with a manifold... they are known as sidemount divers.

 

[OkByMe]

There is another way that may require some machining.. That is to use the manifold valves and take out the crossover. You could then drill and tap the valve plugs for the high pressure female disconnect and hose. The plugs I have are solid, so by the time you drill through it with a #40 drill (to start) and then stop drill for the tap, you would not weaken it.

The hole does not need to be as big as the hole through the high pressure seat, you would need to add some restriction (#40) before the disconnects. Without it If the hose broke, the air coming out would be enormous, blinding and probably cause the tanks to flail around. I have never even thought about opening a cylinder valve under water to see what it would do... You would still use a regulator on each tank, but would not have to swap it. The contents of the tanks manifolded, goes without saying, but I will... have to be the same mix.

And I never said squat about overhead... Who would be dumb enough to test anything without ready access to the surface!

 

[OkByMe]

Bump... Brainstorm in progress.

 

[beanojones]

I get ... why manifolded doubles is better.

It is at least worth pointing out that the evolution of stuff made the manifolded dual outlet tanks a better solution than what came before, but that's because they were a step better than dual tanks with a single outlet. Not necessarily because it is better than independent dual tanks (also with dual outlets)

When rethinking things, it is worth looking at all the presumptions made on the way, and why they were made and when they were made. The are lots of back filled reasons for a lot of scuba setups (and practices). But it is worth noting that scuba is way, way more tied to rationalizations of the why things are the way they happen to have ended up, than it is to actual good reasons, and not just historical/accidental reasons, for why things are the way they are.

Scuba is a non-competitive sport. Which tends to make for a fun activity for everybody, but also one in which pointless/ineffective/inefficient practices are not weeded out through competition, so things change extremely slowly even when they are huge advantages to a new design/system, because competition does not force less effective/efficient means out to pasture, nor does it punish pointless practice out of the sport.

(It's also why we scuba people can get so emotionally attached to however we do it, because without competition to weed out the ineffective, it's only opinion. And we, as people, are way more emotionally tied to our own opinions, and way more emotionally resistant to change, than we would like to think we are.)

It also does not help when that we dive instructors tend to repeat whatever we heard someone else say when we learning, and treat it as fact (by providing back filled rationalizations for out odd beliefs.)

 

[saridnour]

I know this is an old thread but was info I needed. Thanks all!! :meeting:
I wanted to do this with my SM setup (LP manifold - aka LP hose+QD bridging two 1st stages) to support my Full Face Mask (FFM). Both 1st stages would have regs and spg's as one would in a standard SM setup (inc one reg long hosed). I could still dive standard SM and reg swap if needed BUT I could use a FFM with both tanks. I just need to pocket a mask in the event of needing to bail out of the FFM to traditional SM in an emergency.
I could even add a "Inline Shut-Off at First Stage" to both ends of the bridging LP hose and T the FFM between them as then I could isolate either tank by shutting it off and closing the shut off on that end of the lp bridge. Hmmm.. Any reason why this would not work? The other option is to use a "Gas Switch Block" instead of the T and shut off valves. Id then also not need shut off tanks to balance (but more $$ and LP/drysuit Lp's would not share air between tanks, but shouldn't be an issue).
Thoughts?

:support:
-Andy