"soft" HP manifold?

[Lajgaard]

Hi,

I'm looking for a short HP-to-HP port manifold for my two first stages. Like a "soft" manifold to hi-pressure link two tanks by the first stages, as an alternative to a perm. manifold directly between the tank valves (as seen on most twin-tank systems).

This my be don by a short (20-30 cm) HP-hose with a male connector for a std. 7/16" HP port on the first stage. A flex tube of stainless steel to protect this hose will be nice, but not a must. The hose must be able to stand a working pressure at 300 bars.

Please let my know if you have ny idea where to buy a HP-hose lige this - or how to make one my self ... may likely not be possible(!)

Also if you have any experience in costume made HP hoses, please post.


Best Regards,

Peter Hwan Lajgaard
DENMARK

 

[attchoum]

i don't understand what is the adventage of your soft hp to hp manifold beside a real premanent manifold??

 

[The Kraken]

What you describe could be construed as being dangerous to the point of catyclismic!
Imagine, if you would, that you had a piece of defective tubing and it ruptured!

You now have 2 free flowing tanks and no way to shut them off other than turning off both valves. What would you breathe, if you had not redundant air source?

the K

 

[Tiny Bubbles]

It's even more dangerous than that. If you have a leak or a freeflowing regulator, shutting off the tank valve on that side will not stop it! It will also be fed gas through your crossover hose from the 'good' side.

But, for the sake of argument, one could probably be thrown together with a 4552K212 hose from mcmaster-carr and a pair of parker 4-1/4 F5OG adapters, and a shut-off valve for safety.

-Tiny-B.

 

[DA Aquamaster]

The flow rate is pretty low through both a HP hose and through the restricted orifices in the HP ports. This is done to prevent a rapid loss of air in the event you blow an HP hose or spg.

This means that if you're breathing out of one tank at depth, it won't transfer air fast enough to keep them equalized anyway so it is not fully redundant. On the other hand, if you blow a hose, it may lose air faster than you can afford in a soft or hard overhead environment. So the risk is not worth the benefit.

In my opinion, you are far better off sticking with independent doubles and proper gas planning and management if you don't want to go with a hard isolator manifold. With proper gas management you give up very little gas compared to a set of manifolded doubles and they are truly redundant with no need to shut anything to isolate one tank from the other if something fails.

With regard to air crossing over from one tank to another past a closed tank valve, that would not happen even with vintage K or J valves that incorporated HP ports in the valve and you were using those ports as those ports are also downstream of the valve seat.

Your idea does have some merit but it would require a suitably designed (iever-enginered) and well armored hose that also incorporated an isolator valve in the middle. You would then however also have to bore the HP orifices in each first stage out to a larger size. Some regulators would allow this but others would not due to the specific design and internal space available.

 

[JS1scuba]

Hi,

I'm looking for a short HP-to-HP port manifold for my two first stages. Like a "soft" manifold to hi-pressure link two tanks by the first stages, as an alternative to a perm. manifold directly between the tank valves (as seen on most twin-tank systems).

This my be don by a short (20-30 cm) HP-hose with a male connector for a std. 7/16" HP port on the first stage. A flex tube of stainless steel to protect this hose will be nice, but not a must. The hose must be able to stand a working pressure at 300 bars.

Please let my know if you have ny idea where to buy a HP-hose lige this - or how to make one my self ... may likely not be possible(!)

Also if you have any experience in costume made HP hoses, please post.


Best Regards,

Peter Hwan Lajgaard
DENMARK

Peter, we messed with this in the early 90s. To make it work we had to bore out the ends of the HP hoses so there would be sufficient gas equalization. And then we had to use an HP "T" to put an SPG on one side.

What is your application for this ?

Regards,

 

[DA Aquamaster]

There is not really a need for the HP "T" if the first stage has 2 HP ports. Nice to know the wheel is being reinvented though.

 

[vlad_kalish]

Had a similar idea... but after reading through this thread I see why it is a bad one.

But then, what if we have the following setup:
- 2 independent tanks, each with a 1st stage.
- from each 1st stage take an LP hose (1) and connect them through 'Y' connector (with shutoff valve) to one 2nd stage
- from each 1st stage take another LP hose (2) and connect them through 'Y' connector (with shutoff valve) to another 2nd stage

If any of the 2nd stages starts to freeflow -- use the shutoff valve on the 'Y' connector and switch to another 2nd stage.
If any of the 1st stages malfunctions -- turn it off.

So, in essence we have the same setup as a "hard" manifold, with the only difference that the pressure in both tanks might never equalize. But, so what, if one tank has 600 psi and another 400 psi at the end of the dive...

 

[jimandi]

I did it... and you will not like it.... connect the two system on the low-pressure side... have a look at Dual-Tanks

 

[Paladin]

Deleted. This thread is ancient!