Attaching Manifold to Doubles

[do it easy]

I have never seen halcyon valves before but those dip tubes look scary if you are PP blending nitrox.

Your gonna DIE!!! There are a few holes drilled into the side- they are kinda hard to see in the picture. But yeah, that stuff they teach about sharp bends and impingment comes to mind...

 

[wedivebc]

that stuff they teach about sharp bends and impingment comes to mind...

Yeah, that pesky old adibatic compression...

 

[k_Woolfsmith]

Can someone explain this a little further, I have a manifold waiting to be put on new tanks, (exaclty) like the one pitcured, what are the drawbacks? I missed something, Adibiatic pressures, aren't those stems standard on Halcyon manifolds??? Thanks

Karl

 

[wedivebc]

Can someone explain this a little further, I have a manifold waiting to be put on new tanks, (exaclty) like the one pitcured, what are the drawbacks? I missed something, Adibiatic pressures, aren't those stems standard on Halcyon manifolds??? Thanks

Karl

Most dip tubes I have seen (constructed in the last 10 years) have an opening on the bottom which creates a straight through path for gas to flow. The halcyon ones pictured in the link have a pinched off end with a hole drilled to one side. This creates a dead end air space at the end. When gas flows at high velocity such as when a valve is accidently opened too fast for filling the pressure front of the gas flowing against a dead end can heat up quite rapidly due to compression. Should there be any combustable material at the terminus then you might have a very small combustion source. This is even more likely if the tank is pressurized with pure oxygen such as when partial pressure blending of nitrox.
I for one was not aware any company was still selling valves of this construction and will not be PP blending any tanks fitted with halcyon valves in the future.

 

[SparticleBrane]

You can buy Thermo diptubes for $6 from DRE. I wonder if they'd fit the Halcyon manifolds...

 

[do it easy]

I for one was not aware any company was still selling valves of this construction and will not be PP blending any tanks fitted with halcyon valves in the future.

I wonder what the advantage would be to have a pinched off dip tube? Does it mix gasses more efficiently when PP blending? Maybe it would do a better job of preventing debris from blocking the dip tube? With doubles or O2 clean tanks, is this a solution to a non-existant problem? Or maybe it just matches the broken steak knife?

 

[Dan Gibson]

Ever hear someone walk around with a loose dip tube rolling around at the bottom of the tank. It is much easier to tighten the Halcyon dip tubes so they don't come off too easy. I wouldn't worry about adiabatic compression. The hole is on both sides of the dip tube. The picture is a little misleading.

I wonder what the advantage would be to have a pinched off dip tube? Does it mix gasses more efficiently when PP blending? Maybe it would do a better job of preventing debris from blocking the dip tube? With doubles or O2 clean tanks, is this a solution to a non-existant problem? Or maybe it just matches the broken steak knife?

 

[Dan Gibson]

Hand tight only on the valves. No wrench needed unless a gorilla put the valve on or there is corrosion when you take it off. Definitely no mallet.

Uhhhh... Get some Christolube please. Don't use spit. The person who has to disasseble your doubles for VIP will thank you. Also, I don't like the rubber mallet thing. I use a large adjustable wrench. You just want the thing to compress the o-ring a bit. The valve is going to have ~3000psi holding it at the threads. It doesn't need to be cinched down. When you get the doubles assembled, put 100psi or so in the tanks, and dunk the valve and manifold in water and look for bubbles.

The valves are the easy part of this job. It's the manifold bar that's tricky the first couple of times.

 

[wedivebc]

Ever hear someone walk around with a loose dip tube rolling around at the bottom of the tank. It is much easier to tighten the Halcyon dip tubes so they don't come off too easy. I wouldn't worry about adiabatic compression. The hole is on both sides of the dip tube. The picture is a little misleading.

The three components of oxygen service is O2 clean, O2 compatable and O2 design. Although scuba valves by nature don't meet the criteria of O2 design this is a definate design flaw with regard to oxygen service. You might be OK with it but the fact that you feel 2 holes in the dip tube is less of a hazard indicates you don't truly understand the issue.

 

[jim T.]

diveriteexpress.com has a great "manual/description" of how to put dobles together.
Print in out and go at it... hope that helps.