Warning about hot fills!

[Suzuki416]

Can't honestly say that I'd be too concerned about a 6 - 7 minute fill - as long as it ended up close enough to what I asked for - Thats not what I'd call a hot-fill...

I've seen more than a few cylinders filled in less than a minute from banks, not guilty myself though.

think my fastest was 3min... That was a touch warm.. Stopped it at 255 bar (opps) - The whips hadn't been maintained !

 

[divezonescuba]

The guy's garage is in Houston, TX. Its the middle of the summer here with the outside temperature around 100.

It was our tanks that he was renting.

The funny thing is when he returned the tank, he didn't have anything to say other than thank you. If the tanks had cooled lower that 3000 psi, I am sure that he would have had something to say about it. That was why I was so surprised that he filed the Q and A Complaint.

 

[roastbeef]

Scuby doo divers make me laugh.

 

[Wookie]

Did you mean 50 PSI/min or 500PSI/min? Your point is valid but I don't know many (any?) shops that take nearly an hour to fill an AL80. I know Blackbeards had something like a 17cfm compressor that would take a couple hours to fill all the tanks. But when divers are off gassing during their SI, you're not really in a hurry anyways.

50 PSI/min is the recommended filling rate according to CGA (and maybe that's O2 and not air, but I think it's air). Now, go to a gas house and see when they have 75 or 100 O2 or air cylinders on the fill rack, it's easy to maintain 50 PSI/min. It's a little more difficult in a dive shop with 2 fill stations or on a liveaboard with 6.

 

[flots am]

According to this individual, a tank hot filled to 3200 psi would cool down to 2100 psi if it was put in his garage for a week. He also stated that tanks that were hot filled would have a shorter service lifetime. He was so upset that he filed a Q and A on us with our certification agency.

Tell him you're sorry that he's upset with your practices and hope he find a place he likes better.

flots.

 

[Doppler]

Guy's a wanker.


Had a cave fill in super-chilled water one time a while ago.

SPG climbed as we swum into the cave at peacock... bust disk let go a about 60 metres into the peanut tunnel.


Cool fills are not always the solution! LOL

 

[HenrikBP]

50 PSI/min is the recommended filling rate according to CGA (and maybe that's O2 and not air, but I think it's air).

On a recent mix blender course we were recommended fill rates of no more than 60 PSI/min for O2 and ~600 PSI/min for air.

 

[drbill]

One of my PST HP120 tanks failed hydro about 5 years ago due to over expansion. I was told it probably failed due to hot fills. Even the manager of the dive shop where it was filled most often agreed it was probably due to the hot fills.

 

[supergaijin]

Did it fail becasue of hot fills or overfills to compensate for the hot fill?

 

[Crush]

Perhaps he's living in a parallel universe where laws of physics do not apply. . .

Ideal Gas law: P*V/T = constant . . .

You'd have to see a ~50% change in ambient temperature to account for that much of a pressure differential. . .

Let's assume that his garage is 25 C (77 F) - this will be the final temperature (T2C). How hot would your fill have to have been (that is, what is T1C) for the pressure to go from 3200 psi initially (call this P1) to a final pressure of 2100 psi (call this P2)?

P1 / T1K = P2 / T2K
T1K = T2K * P1 / P2

The temperature in Kelvin (T1K and T2K) are converted to Celsius (T1C and T2C) by subtracting 273.

T1C = [(T2C+273) * P1 / P2]-273
= 181 C

In Fahrenheit this 358 degrees. I agree with the leaky valve theory.