Overfill Differences for LDS - Question

[captain]

We all wait for youir results ... well, at least I do.

Picky, picky picky.

I don't have to wait, I know from personal experience.

 

[Thalassamania]

I don't have to wait, I know from personal experience.

But your personal experience is belied by my data. We need a tie breaker.

 

[captain]

But your personal experience is belied by my data. We need a tie breaker.

Come on over, we'll run a side by side test one dry and one with my water bath.

 

[spectrum]

A water bath will help get a nice fill on a HP steel, no question. You do need to make sure that the whip/connection is dry. Around here it's seldom done so the fill area is never awash when I can get it done that way.

I have found fill station gauges to be off on a number of occasions. I go in with my own tank checker.

Having cold air in the bank makes a big difference compared to getting hot gas right off the compressor. If they ended the day with full banks first fills of the day, while your steel is still cool from the night can yield great results.

If you can drop them off and get a top-off latter that works. We have dropped them off and once the fills were started gone out to eat, and topped off before leaving. Ideally you want to allow about 4 hours for all of the gas in the cylinder to cool but much of the cooling happens quicker.

Slow fills are the way to go, you want to just barely hear the air flowing. 15 minutes if actual filling is good.

Unless you have a conscientious shop/fill operator be prepared to do some education and enforcement.

Pete

 

[Hoosier]

Within 15 min filling time, I think shop 2 is more likely correct figure without considering a wet fill. The depreciation in pressure is more than 200 psi based on my experience. I am sick and tired of leaving my tanks, arguing a right fill, and paying more because it is a high pressure. So, get your own air source with your buddies and forget it.

 

[spectrum]

So, get your own air source with your buddies and forget it.

I agree that is a tempting thought. The cost per fill alone does not justify it. When you factor in the runaround, hassles and independence it's appealing.

My wife has already blessed the idea, what a woman!

Pete

 

[Hoosier]

I agree that is a tempting thought. The cost per fill alone does not justify it. When you factor in the runaround, hassles and independence it's appealing.


Pete

Pete...

Yes, you are right on an air fill. But, if you think about a nitrox or trimix fill, it won't take a long to catch up an initial investment. In addition, if you have a few more local buddies, it is much quicker than your thought.

And, think about a travel cost and time cost... Oh~~~ I gave it up.

 

[Divin'Papaw]

Within 15 min filling time, I think shop 2 is more likely correct figure without considering a wet fill. The depreciation in pressure is more than 200 psi based on my experience. I am sick and tired of leaving my tanks, arguing a right fill, and paying more because it is a high pressure. So, get your own air source with your buddies and forget it.

Hey WT ... I'm your buddy, right?!!! Me likes your idea!

 

[ams511]

I beach dive Venice (FL West Coast) and West Palm Area (FL East Coast). These are both ~3hr drives for me so I try and make a day of it with two dives.

Thanks for the feedback - I do know that the Shop with the larger loss in pressure uses banks and I am not sure of the other shop.

You should try Vero, it is closer and the beach diving is excellent in the summer.

 

[GeorgeC]

That is not actually true. The first law of thermodynamics is heat can not be created or destroyed. There is not heat generated when transferring gas from one container to another other than the heat picked up from the piping and valves between the source and the destination container. Ever notice as you tranfer from a bank it gets cooler? There is more heat from compressed air because usually ambient air has more heat energy than compressed air that has been allowed to cool off for a period of time.

Even though ambient compressed air or actively compressed air will have more heat than that of banked compressed air there could be a greater amount of heat generated when filling from the bank. It all depends on the fill hose size, length and the fill rate. All of these factors contribute to the friction the air must overcome when going from the bank to the empty cylinder.

If the person fills the tank from a bank at an extremely fast rate it could be much warmer than directly from a compressor.