Tanks - True cost of ownership

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

Hey guys the toilet is getting full can we flush this pissing match down the drain.

LOL
We are in agreement...there is no contest here. Sorry your day is going so poorly.

Sent from my SAMSUNG-SM-G900A using Tapatalk
 
I'm in no contest! :)
 
Install valve, open valve, put in deep freezer overnight. Remove tank and close valve. Allow to warm, take to shop for filling. Tank now has slight positive pressure. Done.

Sounds like a recipe for moisture in the tank to me.
 
Moisture from where?
 
Sounds like a recipe for moisture in the tank to me.

Moisture from where?

A little phenomenon called condensation.

Doing some rough calculations it would seem that the freeze with an open valve followed by closing the valve and allowing it to return to ambient would only get you an extra psi or 2. And, on a worst case basis that gas would have a relative humidity of about 25% at room temperature so the moisture content would be about what you would expect from opening a tank up to do a visual inspection. No big deal.

Or you could freeze the tank with the valve closed and open and close it when you remove it from the freezer to get almost the same pressure increase with much less moisture.

But that sure seems like a lot of trouble to gain less than a couple psi that may not even be audible.
 
A little phenomenon called condensation.

This reminded me of one of those “tricks” I have seen that could be considered a little over the top by some. Before the first fill after installing a valve, pressurize the cylinder to 50 PSI and bleed it off to near zero a few times. The theory is that 30-50 PSI isn’t enough to cause much condensation due to compression and purging a few cycles with very dry air “should” reduce the amount of moisture trapped in the cylinder.

I have never seen it actually tested and it probably wouldn’t matter very much if the first fill is used soon after filling. Every fill cycle dilutes any ambient moisture trapped in the cylinder when the valve is screwed on. I guess you could get really anal and drop a hose in the cylinder to blow dry air in before installing the valve as well.

Why even mention it? Maybe it might help people who have not thought about it very much to visualize the role of moisture in cylinders.
 
https://www.shearwater.com/products/peregrine/

Back
Top Bottom