How often do you actually get a full tank fill?

[thomschoon]

Only one place in South Florida has tried to give short fills, they fill so fast the tank is barely able to be handled it is so hot. I always check pressure and gas % as I usually get nitrox. I make them top off and try to never be there when they are slammed. Otherwise I have a great place in Jax that knows how to fill and blend so I have zero issues.

 

[USdiver1]

It has been my experience that a water bath is overrated as a means of getting a full fill. Water entry, plus the fact that unless you have refrigerated water, the amount of cooling will be minimal.
Fill, cool and top off work best if using a cascade fill system. If a direct line from the compressor is used, adiabatic heating will affect your fill. Overfill [cave fill] is an effective means to counter the adiabatic heating issue.

 

[Divin'Papaw]

It has been my experience that a water bath is overrated as a means of getting a full fill. Water entry, plus the fact that unless you have refrigerated water, the amount of cooling will be minimal.
Fill, cool and top off work best if using a cascade fill system. If a direct line from the compressor is used, adiabatic heating will affect your fill. Overfill [cave fill] is an effective means to counter the adiabatic heating issue.

The shop I use has cold water. Really cold. It absolutely makes a difference. At least in the context where I've seen it used and also not used in South Florida. The shop many of us use in South Florida does both ... very cold bath and fill to 3600-3800. Results in VERY nice fills!

 

[rob.mwpropane]

Getting a cave fill here is very difficult to obtain.
My shop is pretty good though, I get 2500 in my LP72's and a full 3500-3600 (when cold) in 3442's so I can't bitch too much.
I got four grand once in my 120 and danced all the way to the dive site.
It helps to pick them up later and request that they get "topped up".
Other than finding a shop that gets it, the other alternative is to buy your own compressor.

Why so low in the lp's? Because they won't?

I love my lp's. I take them to 33-3400 and they dive likea dream (85's).

 

[Tracy]

Seems silly to have all the numbers on the gauge if you aren't going to use them.

 

[Scott G. Bonser]

You need to have serious talk with the shop and get a confirmation of what their attitude is.

At the one I go to, they pretty much always slam them up to 3800 and they have a water bath to keep them somewhat cool. I have more problems with them filling the 2400 psi tanks to 3000, but about every 5-th time, they accidentally fill my LP to 3800. I don't expect a great level of competence from the people who actually fill tanks.

I have vintage double hose equipment and have shops fill to only 2250psi. That is what the vintage gear is rated for. I even wrote in black sharpie. ‘Fill to 2250 psi only’. Some shops and tank fillers go way overboard and I have to check the filled pressure and bleed off accordingly.

 

[bletso]

Two option are available to help with getting a “full fill.” The tank can be filled in a water bath to help keep it cool during filling, or the tank can be filled to working pressure and then topped off back to working after it cools.

Overfilling so it drops to working pressure once it cools is not a recommended option.

Actually your last statement is incorrect as it is exactly what fill plants do all over the world. Take a temperature reading and fill to temp/pressure reading and when it cools down it will be at correct pressure at 68 f or 20 C. What do you think happens to pressure in the hot trunk of your vehicle. i.e. if filled to let's say 3000 psig at 20C and and then in your car trunk @ 46C (120F). It will read 3284 PSIG. Guaranteed - basic gas laws.

 

[Tracy]

I have vintage double hose equipment and have shops fill to only 2250psi. That is what the vintage gear is rated for. I even wrote in black sharpie. ‘Fill to 2250 psi only’. Some shops and tank fillers go way overboard and I have to check the filled pressure and bleed off accordingly.

What gear was designed for 2250? Sure there were some 1800 psi co2 bottles converted for scuba use back in the early early days, but I don't know of any commercial gear made for that.
Most of the early scuba tanks were 2475 psi and gear was designed for the tank pressure available at the time.

You can fill to whatever pressure make you happy, but I don't think your gear design is the limiting factor.

 

[rjack321]

Getting a cave fill here is very difficult to obtain.
My shop is pretty good though, I get 2500 in my LP72's and a full 3500-3600 (when cold) in 3442's so I can't bitch too much.
I got four grand once in my 120 and danced all the way to the dive site.
It helps to pick them up later and request that they get "topped up".
Other than finding a shop that gets it, the other alternative is to buy your own compressor.

Why so low in the lp's? Because they won't?

I love my lp's. I take them to 33-3400 and they dive likea dream (85's).

Because lp72s are a 2200 psi tank and plus rated at 2420.... Being 50 years old with some of the thinnest walls ever is another reason to not go crazy overfilling them. They are hydroed at 3600

 

[Sea Gar]

I literally just picked up my 2 hp130…. 1 was filled to 2200 and the other 3100! Absolutely insane! Guess where I’ll never go for a tank fill.